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heclann — Sat, 14 Nov 2009 09:24:47 CST

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Cell Respiration and Metabolism

flattail — Thu, 10 Sep 2009 20:51:42 CDT

Cellular respiration--the process of making ATP, can be divided into Glycolysis, Kreb's Cycle (also called Citric Acid Cycle), and the Electron Transport Chain

Glycolysis

Glycolysis refers to the conversion of glucose to two molecules of pyruvic acid.

In the process, two molecules of ATP are consumed and four molecules of ATP are formed. Thus, there is a net gain of two ATP.
In the steps of glycolysis, two pairs of hydrogens are released. Electrons from these hydrogens reduce two molecules of NAD.
glycolysis can be considered the 1st step in anaerobic respiration.

When respiration is anaerobic, reduced NAD is oxidized by pyruvic acid, which accepts two hydrogen atoms and is thereby reduced to lactic acid.

Skeletal muscles use anaerobic respiration and thus produce lactic acid during exercise. Heart muscle respires anaerobically for just a short time, under conditions of ischemia.
Lactic acid can be converted to glucose in the liver by a process called gluconeogenesis.
Liver makes and stores glycogen as well as the skeletal muscles.glucigon stimulates breakdown of glycogen.
when your body needs more energy the skeletal muscles make the glycogen.
NOTE: The liver release glucose into the bloodstream by breaking down glycogen.The skeletal muscles cannot due to the lack of enzyme to remove phosphate from the glucose (a phosphorylated molecule cannot get through the cell membrane, so even one muscle cell cannot share glucose with a muscle cell next to it).

Glycolysis and the Lactic Acid Pathway
In cellular respiration, energy is released by the stepwise breakdown of glucose and other molecules, and some of this energy is used to produce ATP. The complete combustion of glucose requires the presence of oxygen and yields thirty ATP for each molecule of glucose. However, some energy can be obtained in the absence of oxygen by the pathway that leads to the production of lactic acid. This process results in a net gain of two ATP per glucose.

The expression "lactic acid" is used most commonly by athletes to describe the intense pain felt during exhaustive exercise, especially in events like the 400 metres and 800 metres. When energy is required to perform exercise, it is supplied from the breakdown of Adenosine Triphosphate (ATP). The body has a limited store of about 85 grams of ATP and would use it up very quickly if we did not have ways of resynthesizing it. There are three systems used to resynthesize ATP: ATP-PC, lactic acid and aerobic. More discussion of lactic acid can be found on this sub page.

All of the reactions in the body that involve energy transformation are collectively termed metabolism.
- Metabolism may be divided into two categories: anabolism and catabolism.
- Catabolic reactions release energy, usually by the breakdown of larger organic molecules into smaller molecules.
  - The catabolic reactions that break down glucose, fatty acids, and amino acids serve as the primary sources of energy for the synthesis of ATP.
- Anabolic reactions require the input of energy and include the synthesis of large energy-storage molecules, including glycogen, fat, and protein.
When a molecule is completely broken down to carbon dioxide and water within a cell, the final electron acceptor is always an atom of oxygen. Because of the involvement of oxygen, the metabolic pathway that converts molecules such as glucose or fatty acid to carbon dioxide and water (transferring some of the energy to ATP) is called aerobic cell respiration.
The breakdown of glucose for energy begins with a metabolic pathway in the cytoplasm known as Glycolysis. (glykys = sweet and lysis = loosening) Glycolysis is the metabolic pathway by which glucose is converted into two molecules of pyruvic acid, or pyruvate.
The metabolic pathway by which glucose is converted to lactic acid is frequently referred to as anaerobic respiration. The term anaerobic means that oxygen is not used in the process.
- Red blood cells, which lack mitochondria, can use only the lactic acid pathway; therefore they cannot use oxygen. This spares the oxygen they carry for delivery to other cells.

Aerobic Respiration
Aerobic respiration requires oxygen in order to generate energy (ATP). It is the preferred method of pyruvate breakdown from glycolysis and requires that pyruvate enter the mitochondrion to be fully oxidized by the Krebs cycle. The product of this process is energy in the form of ATP.

Glycogenesis
Glycogenesis is the process of glycogen synthesis, in which glucose molecules are added to chains of glycogen. This process is activated by insulin in response to high glucose levels, for example after a carbohydrate containing meal.

Glucose is converted into Glucose-6-Phosphate by the action of Glucokinase or Hexokinase.
Glucose-6-Phosphate is converted into Glucose-1-Phosphate by the action of Phosphoglucomutase, passing through an obligatory intermediate step of Glucose-1,6-Phosphate.
Glucose-1-Phosphate is converted into UDP-glucose by the action of Uridyl Trasnferase (also called UDP-glucose pyrophosphorylase) and Pyrophosphate is formed, which is converted by pyrophosphatase into 2 molecules of Pi.
Glucose molecules are collected in a chain by Glycogen synthase, which must act on a pre-existing glycogen primer or glycogenin (small protein that forms the primer).
Branches are made by Branching enzyme which transfers the end of the chain onto an earlier part via alpha-1:6 glucosidic bond, forming branches, which further grow by addition of more alpha-1:4 glucosidic units

CORI CYCLE
When muscles require energy for short duration or strenuous movements, muscle cells default to anaerobic glycolysis to quickly produce abundant amounts of ATP. The byproduct of anaerobic glycolysis, lactate, diffuses into the blood and is taken up by the liver, where it is converted back into pyruvate by the enzyme lactate dehydrogenase. Pyruvate is then converted back into glucose via gluconeogenesis. The newly formed glucose is released into the blood to be used once again for energy by the red blood cells and muscle.

image: how the cori cycle works in the body.

Krebs Cycle
The first reaction uses an enzyme to remove the acetyl from Acetyl Co-A. This new two carbon molecule can now bond with a four carbon molecule called oxalacetate. This new molecule has six carbons and is called citrate. An isometric conversion takes place and isocitrate forms. From there CO2 is released and NAD picks up a H+ ion. Now the isocitrate has become ketoglutarate. Another CO2 is released from the ketoglutarate, this frees an H+ ion which bonds with a NAD ion making another NADH. The Co-A is now replaced with a phosphate from the matrix now forming Succinyl Co-A and an ADP is bonded with a phosphate to make ATP creating succinate. FAD comes in and takes a H+ ion and becomes FADH2. In doing so succinate turns into Fumarate. Now H20 is added to Fumarate to form Malate. Now another NAD is reduced and Oxalacetate if reformed! The cycle is now ready to be repeated.

Electron Transport Chain
Reduced NAD and FAD donate their electrons to an electron-transport chain of molecules. Each element in the chain becomes oxidized as it donates electrons to the next piece of the chain. This creates the energy for ATP. In the end electrons are given to oxygen which is then reduced to water when two hydrogen atoms are added.

Metabolism Of Lipids and Proteins
I. In lipolysis, triglycerides yield glycerol and fatty acids.
a.Glycerol can be converted to phosphoglyceraldehyde and used for energy.
b. In the process of beta-oxidation of fatty acids, a number of acetyl CoA molecules are produces.
c. processes that operate in the reverse direction can convert glucose to triglycerides.

II. Amino acids derived from the hydrolysis of proteins can serve as sources of energy.
a. through transmination, a particular amino acid (pyruvic acid or one of the Krebs Cycle acids) can serve as substrates to for a new amino acid and a new keto acid.
+it will not change the shape or quality of the enzyme so that it can be recycled and used again.
b. in oxidative deamination, amino acids are converted into keto acids as their amino group is incorporated into urea.

III. Each organ uses certain blood-borne energy carriers as its preferred energy source.
a. the brain has an almost absolute requirement for blood glucose as its energy source.
b. during exercise, the needs of skeletal muscles for blood glucose can be met by glycogenolysis and by gluconeogenesis in the liver.

Uses of different energy sources- all cells in the body could not use the same energy source (for example, glucose) because that energy type would deplete quickly and would result in cellular starvation. Different types of energy sources include glucose, ketone bodies, fatty acids, lactic acid, and amino acids. Even if glucose is the preferred energy source of many organs, these organs will spare glucose in times of fasting and use fatty acids, ketone bodies and lactic acid.

Ketone Bodies are derivatives of fatty acids converted by the liver. A rapid breakdown of fat results in elevated levels of ketone bodies in the blood. This could be due to strict low carbohydrate diets and in uncontrolled diabetes mellitus. The high levels of ketone bodies in the blood is called ketosis. If there are sufficient amounts of ketone bodies in the blood to lower the blood pH, the condition is called ketoacidosis which when severe enough can lead to coma and death.

Here are some ways, system by system, that the body is using ATP

INTEGUMENTARY SYSTEM

The skin synthesizes vitamin D from a derivative of cholesterol
The metabolic rate of the skin varies greatly, and depending upon ambient temperature.

NERVOUS SYSTEM

The aerobic respiration of glucose serves most of the energy needs of the brain.
Regions of the brain with a faster metabolic rate, resulting from increased brain activity, receive a more abundant blood supply than regions with a slower metabolic rate. This has been used to map brain function by giving subjects radioactively-labeled glucose and observing the glucose uptake with Positron Emission Tomography (however, this method has largely been replaced by functional MRI techniques--for more info see this article on neuroimaging)

ENDOCRINE SYSTEM

Hormones that bind to receptors in the plasma membrane of their target cells activate enzymes in the target cell cytoplasm.
Hormones that bind to nuclear receptors in their target cells alter the target cell metabolism by regulating gene expression.
Hormonal secretions from adipose cells regulate hunger and metabolism
Anabolism and catabolism are regulated by a number of hormones.
Insulin stimulates the synthesis of glycogen and fat
The adrenal hormones stimulate the breakdown of glycogen, fat, and protein.
Thyroxine stimulates the production of a protein that uncouples oxidative phosphorylation. This helps to increase the body's metabolic rate.
Growth hormone stimulates protein synthesis.

MUSCULAR SYSTEM

The intensity of exercise that can be performed aerobically depends on a person's maximal oxygen uptake and lactate threshold.
The body consumes extra oxygen for a period of time after exercise has ceased. This extra oxygen is used to repay the oxygen debt incurred during exercise.
Glycogenolysis and gluconeogenesis by the live help to supply glucose for exercising muscles
Trained athletes obtain a higher proportion of skeletal muscle energy from the aerobic respiration of fatty acids than do non-athletes.
Muscle fatigue is associated with anaerobic respiration and the production of lactic acid.
The proportion of energy derived from carbohydrates or lipids by exercising skeletal muscles depends on the intensity of the exercise.

CIRCULATORY SYSTEM

Metabolic acidosis may result from excessive production of either ketone bodies or lactic acid.
The metabolic rate of skeletal muscles determines the degree of blood vessel dilation, and thus the rate of blood flow to the organ.
Atherosclerosis of coronary arteries can force a region of the heart to metabolize anaerobically and produce lactic acid. This is associated with angina pectoris.

RESPIRATORY SYSTEM

Ventilation oxygenates the blood going to the cells for aerobic cell respiration and removes the carbon dioxide produced by the cells.
Breathing is regulated primarily by the effects of carbon dioxide produced by aerobic cell respiration.

URINARY SYSTEM

The kidneys eliminate urea and other waste products of metabolism from the blood plasma.

DIGESTIVE SYSTEM

the liver contains enzymes needed for many metabolic reactions involved in regulating the blood glucose and lipid concentrations.
The pancreas produces many enzymes needed for the digestion of food in the small intestine.
The digestion and absorption of carbohydrates, lipids, and proteins provides the body with the substrates used in cell metabolism
Vitamin A and D help to regulate metabolism through the activation of nuclear receptors, which bind to regions of DNA

REPRODUCTIVE SYSTEM

The sperm do not contribute mitochondria to the fertilized oocyte.
The endometrium contains glycogen that nourishes the developing embryo.

REVIEW QUESTIONS

1. Ketone bodies are derived from ______.
a. fatty acids
b. glycerol
c. glucose
d. amino acids

2. The conversion of lactic acid to pyruvic acid occurs__________.
a. in anaerobic respiration.
b. in the heart, where lactic acid is aerobically respired.
c. in the liver, where lactic acid can be converted to glucose.
d. in both a and b
e. in both b and c

3. All of the following are formed as a result of the electron-transport chain except:
a. carbon dioxide
b. oxidized NAD
c. water
d. ATP

4. When glucose is catabolized under aerobic conditions, ________ will cross the mitochondrial wall and enter the Krebs cycle.
a. carbon dioxide
b.pyruvate
c. lactate
d. acetyl CoA

5. Anaerobic metabolism of glucose results in an oxygen debt that is the amount of oxygen needed to metabolize the ______ that is produced.
a. carbon dioxide
b. lactic acid
c. glycogen
d. fatty acid

6.Which of the following statements describes the role of the electron transport chain?

a. The electron transport chain makes ATP.

b. The electron transport chain produces carbon dioxide.

c. The electron transport chain is a reducing agent for NAD.

d. The electron transport chain is an oxidizing agent for FADH2.

7. How many molecules of ATP are produced per molecule of glucose during aerobic respiration?

a. 30

b. 4

c. 24

d. 20

8. What percent of Glucose Energy forms ATP bonds?
a. 20%
b. 30%
c. 40%
d. 50%

9. After glycolysis takes place in the cell's cytoplasm, the pyruvic acid molecules travel into the interior of the mitochondrion. Once the pyruvic acid is inside, ___________ is enzymatically removed from each three-carbon pyruvic acid molecule to form acetic acid.
a. oxygen
b. water
c. carbon dioxide
d. ATP

10. The term _________ state is often used to describe the balance of NAD+/NADH and NADP+/NADPH in a biological system such as a cell or organ.
a. oxidation
b. redox
c. anaerobic
d. metabolic

11. How many ATP molecules are produced from one glucose molecule if it went through the whole cellular respiration cycle? (glycolysis, Krebs cycle , and the electron transport chain)
a. 2
b. 12
c. 36
d. 46

12. What organic molecule has to be present in order to to go through the Krebs Cycle and Electron Transport Chain?
a. protein
b. oxygen
c. carbon dioxide
d. sodium

13. At the end of the electron transport chain oxygen accepts the electron and what is produced?
a. hydrogen
b. glucose
c. ATP
d. Water

14. The Cori Cycle is an exchange between what two parts of the body?
a. heart and lungs
b. skeletal muscle and liver
c.brain and kidney
d.heart and stomach

15. What is the difference between oxidation and reduction?
a.oxidation gives ATP reduction takes ATP away.
b. oxidation uses white blood cells and reduction red blood cells.
c. oxidation describes the lost of electrons and reduction described the gain of electrons.
d. none of these above.

16.Aerobic respiration of glucose serves most of the energy needs of the:
a. brain
b. heart
c. hypothalamus
d. lungs
e. bones

17. When skeletal muscles lack sufficient oxygen, there is an increased blood concentration of ____________.
a. pyruvic acid.
b. lactic acid.
c. ATP.
d. glucose.

Study of Body Function

tseripye — Wed, 02 Sep 2009 00:41:09 CDT

Chapter Objectives

1. describe in a general way, the topics studied in physiology and the importance of physiology in modern medicine.
2. describe the characteristics of the scientific method.
3. define homeostasis and describe how this concept is used in physiology and medicine.
4. explain the nature of negative feedback loops and how these mechanisms act to maintain homeostasis.
5. explain how antagonistic effectors help to maintain homeostasis.
6. explain the nature of positive feedback loops and how these function in the body.
7. distinguish between intrinsic and extrinsic regulation, and explain, in a general way, the roles of the nervous and endocrine systems in body regulation.
8. explain how negative feedback inhibition helps to regulate the secretion of hormones, using insulin as an example.
9. list the four primary tissues and their subtypes and describe the distinguishing features of each primary tissue.
10. relate the structure of each primary tissue to its functions.
11. describe how the primary tissues are grouped into organs, using the skin as an example.
12. describe the nature and significance of the extracellular and intracellular compartment of the body and explain the significance of this compartmentalization.

Introduction to Physiology

Here is a fun video introducing physiology

Scientific Method

Difference between a hypothesis and a theory

Theories are statements of the general world that incorporate a number of hypotheses. A hypothesis is a step in the scientific method that is capable of being refuted by experiments, observations, or the natural world.
Example of using the Scientific Method: New drug developments
- When a new drug is suggested by experiments:
  - Its effectiveness and toxicity is tested first in tissue culture, rats and mice.
    - If it is effective and safe, clinical trials are performed.
    - Phase I Trials: Toxicity and metabolism tested in healthy human volunteers.
    - Phase II Trials: Effectiveness and toxicity tested in target population.
    - Phase III Trials: Widespread test of drug in diverse population.
    - Phase IV Trials: Drug is tested for other potential uses.

History of Physiology

Father of Physiology: Erasistratus, he attempted to apply physical laws to function. 304-250 b.c?
Aristotle, and Galen were also noted in their work.
Father of modern physiology is Claude Bernard. He noted the constancy of the body regardless of the outside environment. Walter Cannon coined the term homeostasis.(1813-1878)

Homeostasis and Feedback Control

The human body consists of trillions of cells all working together for the maintenance of the entire organism. While cells may perform very different functions, all the cells are quite similar in their metabolic requirements. Maintaining a constant internal environment with all that the cells need to survive (oxygen, glucose, mineral ions, waste removal, and so forth) is necessary for the well-being of individual cells and the well-being of the entire body. The varied processes by which the body regulates its internal environment are collectively referred to as homeostasis. The word comes from the Greek homoios (same, like, resembling) and stasis (to stand, posture).

Positive and Negative Feedback

When a change of variable occurs, there are two main types of feedback to which the system reacts:

Negative feedback: This is how the body regulates most systems. Negative feedback is a reaction in which the system responds in such a way as to reverse the direction of change. Since this tends to keep things constant, it allows the maintenance of homeostasis. For instance, when the concentration of carbon dioxide in the human body increases, the lungs are signaled to increase their activity and expel more carbon dioxide. Thermo regulation is another example of negative feedback. When body temperature rises, receptors in the skin and the hypothalamus sense a change, triggering a command from the brain. This command, in turn, effects the correct response, such as sweating and vasodilation to decrease the body temperature.
- Set point: The normal levels of the body, example there is a set point for the body temperature , blood glucose concentration.
- Integrating center: When the sensors detect a deviation from a particular set point they relay this to the integrating center.
- Effectors: Defend the set point against deviation. Muscles or glands act to restore the set point.
- Example: The thermostat of an air conditioner or heater has a set temperature like a set point. When the thermostat detects temperature deviation a sensor will tell the integration center to activate the effectors to start the air conditioner or heater to return the temperature to the set point.

Positive feedback: A response to amplify the change in the variable. This has a destabilizing effect, so does not result in homeostasis. Positive feedback is less common in naturally occurring systems than negative feedback, but it has its applications, particularly when a response should be amplified. For example, in nerves, a threshold electric potential triggers the generation of a much larger action potential. Blood clotting and events in childbirth are other types of positive feedback. In childbirth, pressure on the cervix causes release of oxytocin from the hypothalamus. The oxytocin stimulates uterine contraction, which causes even more pressure on the cervix (and thence more oxytocin released). This continues, with more and more oxytocin being released and the uterus contracting more and more frequently. The cycle is broken when the baby is born and there is no more pressure on the cervix. All positive feedback cycles need something to stop the cycle--otherwise it would cycle out of control.
Here is a video that gives an example of positive and negative feedback. For the positive feedback example, estrogen stimulates (has a positive effect upon) the release of hormones (GnRH and LH) which in turn increase the levels of estrogen. In the negative feedback, progesterone inhibits the release of GnRH and LH, and estrogen levels fall.

Neural and Endocrine Regulation

Nervous System

The nervous system, along with the endocrine system, serves as the primary control center of the body working below the level of consciousness. For example, the hypothalamus of the brain is where the body's "thermostat" is found. The hypothalamus also stimulates the pituitary gland to release various hormones that control metabolism and development of the body. The sympathetic and parasympathetic divisions of the nervous system alternatively stimulate or inhibit various bodily responses (such as heart rate, breathing rate, etc) to help maintain proper levels. It also controls contractions like the arrector pili muscles (involved in thermo regulation) and skeletal muscles, which in addition to moving the body, also cause bone thickening and maintenance, which affects bone composition. The nervous system also regulates various systems such as respiratory (controls pace and depth of breathing), cardiovascular system (controls heart rate and blood pressure), endocrine organs (causes secretion of ADH and oxytocin), the digestive system (regulates the digestive tract movement and secretion), and the urinary system (it helps adjust renal blood pressure and also controls voiding the bladder). The nervous system is also involved in our sexual behaviors and functions.

Endocrine System

The endocrine system consists of glands which secrete hormones into the bloodstream. Each hormone has an effect on one or more target tissues. In this way the endocrine system regulates the metabolism and development of most body cells and body systems. To be more specific, the Endocrine system has sex hormones that can activate sebaceous glands, development of mammary glands, alter dermal blood flow and release lipids from adipocytes and MSH can stimulate melanocytes on our skin. Our bone growth is regulated by several hormones, and the endocrine system helps with the mobilization of calcitonin and calcium. In the muscular system hormones adjust muscle metabolism, energy production, and growth. In the nervous system hormones affect neural metabolism, regulate fluid/electrolyte balance and help with reproductive hormones that influence CNS development and behaviors. In the Cardiovascular system we need hormones that regulate the production of RBC's, elevate and lower blood pressure. Hormones also have anti-inflammatory affects as well as stimulates the lymphatic system. In summary, the endocrine system has a regulatory effect on basically every other body system.

Feedback Control of Hormone Secretion

Hormone secretion happens in response to a specific chemical stimuli. In order for the body to keep homeostasis it has a closed-looped system called negative feedback inhibition. An example of this is the hormone insulin which secretes when there is a rise in blood glucose. Insulin causes the lowering of blood glucose which then inhibits further secretion of insulin which brings our body back to a state of homeostasis.

The Primary Tissues

The basic unit of structure and function are cells. Cells that are grouped together to perform a similar function are called tissues. There are four major tissues in the body, the primary tissues:

Muscle Tissue- Specialized for contraction. There are three types:

Skeletal Muscle- Most often attached to bones at both ends by means of tendons. This contractions causes the skeletal frame to move. The tongue, superior esophagus, anal sphincter, and diaphragm are exceptions because they do not make the skeletal frame move but are composed of skeletal muscle. It is striated tissue and arranged in bundles. It is in parallel arrangement to allow movement to be individual.

Cardiac Muscle-Cardiac muscle is striated and found only around the heart. Myocardial cells are short, branched and are interconnected to form a continuous fabric. Cardiac muscle cells have tight contacts between them that stain darkly--these are called intercalated discs. The intercalated discs allow depolarization (which starts at the sinoatrial node, the heart's pacemaker) to spread between cells so that they all contract as a unit. These electrical connections between adjacent muscle cells are found only in cardiac muscle.

Smooth Muscle-No striations seen when observed under the microscope. Found in digestive tract, blood vessels, bronchiole's, and the ducts of the urinary and reproductive systems. The uterus and bladder are examples of organs with thick layers of smooth muscle. Within tubes (such as the GI tract or blood vessels) the smooth muscle is found in a circular layer and a longitudinal layer. These two layers work together to move food smoothly through the digestive tract (this movement is called peristalsis)

Nervous Tissue- The function of Nervous Tissue is to communicate between parts of the body. It is composed of neurons and neuroglia. All nervous tissue of an organism makes up its nervous system (Brain, Spine, Spinal Cord and nerves throughout the organism). Nervous tissue is made of nerve cells. These cells react to stimuli and bring about a response.

Connective Tissue- Involved in structure and support.Blood, cartilage, and bone are considered connective tissues. Loose connective tissue holds organs and epithelial in place. Dense connective tissue forms ligaments and tendons.

Epithelial Tissue- Composed of a layer of cells. It lines both outside (skin) and inside cavities of the body. Epithelial cells are classified by their shape, stratification, and specializations.

Squamous cells- Flat cells with an irregular flattened shape.
Cuboidal cells- Have a shape similar to a cube, meaning its width is the same size as its height.
Columnar cells- Are taller than they are wide.
Transitional cells- Found lining organs that can stretch, such as the bladder. Since the cells can slide over each other, the appearance of this epithelium depends on whether the organ is distended or contracted: if distended, it appears as if there are only a few layers; when contracted, it appears as if there are several layers.

Organs and Systems

Organ: An Organ is a structure that has more than one of the tissues, usually all four. Tissues within the organ all serve a purpose for the function of the particular organ. We often think of the heart, lungs, or liver as examples of organs, but the skin is also an organ (the largest one), and every bone is an organ. Often an organ will have one main tissue (such as cardiac muscle in the heart).
System: Different organs of the body that work together to perform related functions. The entire body can be looked at as composed of nine major systems: Integumentary, Nervous, Skeletal, Muscular, Circulatory, Immune, Respiratory, Urinary, Digestive, and Reproductive. Each system has its own organs which carry out the functions of that system.

Muscular System

The muscular system is one of the most versatile systems in the body. The muscular system contains the heart, which constantly pumps blood through the body. The muscular system is also responsible for involuntary (e.g. goosebumps, digestion, breathing) and voluntary (e.g. walking, picking up objects) actions. Muscles also help protect organs in the body's cavities

Cardiovascular System

The cardiovascular system, to needing to maintain itself within certain levels, plays a role in maintenance of other body systems by transporting hormones (heart secretes ANP and BNP) and nutrients (oxygen, EPO to bones,etc.), taking away waste products, and providing all living body cells with a fresh supply of oxygen and removing carbon dioxide. Homeostasis is disturbed if the cardiovascular or lymphatic systems are not functioning correctly. Our skin, bones, muscles, nervous system, endocrine, lymphatic system, lungs, digestive tract, urinary system and reproductive use the cardiovascular system as its "road" or "highway" as far as distribution of things that go on in our body. There are many risk factors for an unhealthy cardiovascular system. Some diseases associated are typically labeled "uncontrollable" or "controllable." The main uncontrollable risk factors are age, gender, and a family history of heart disease, especially at an early age.

Digestive System

Without a regular supply of energy and nutrients from the digestive system all body systems would all surely suffer. The digestive system absorbs organic substances such as, vitamins, ions, and water that are needed all over the body. In the skin the digestive tract provides lipids for storage in the subcutaneous layer. Food goes through three types of processes in the body: digestion, absorption, and elimination. Mechanics of digestion can be chemical digestion, movements, ingestion absorption, and elimination. In order to maintain a healthy and efficient digestive system we have to remember the components involved.

Body-Fluid Compartments

All tissues,organs, and systems can be divided into Two major compartments.

Intracellular compartment(inside the cell)
Extracellular compartment(outside the cell)

These two compartment are primarily water, however, they are separated by the cell membrane surrounding each cell. The extracellular compartment is divide into two sections one being blood plasma and the other interstitial fluid(tissue fluid). Blood plasma and tissue fluid communicate freely through blood capillaries in most parts of the body.

Review Questions

1. What does a single celled protozoan need?
a. energy
b. building blocks
c. ATP
d. minerals
e. all of the above

2. The cell expends a lot of its energy to maintain a charge across its membrane, it does this by actively:
a. pumping potassium out
b. pumping sodium in
c. pumping potassium in and sodium out
d. a and b only
e. none of the above

3. The body is _______% fluid.
a. 52
b.89
c.56
d.10

4. Fluid inside the cell is called?
a.blood
b.cytoplasm
c.urea
d.intracellular fluid

5._______ are organized into different functional structures and are highly dependent upon each other.
a. atoms
b. DNA strands
c. cells
d. dendrites

6. How many cells are in the human body?
a. 600 thousand
b. One million
c. Six billion
d. 100 trillion

7. What is interstitial fluid similar to?
a. plasma
b. blood
c. water
d. saliva

8. Adult stem cells can be found in all of the following locations, except:
a. bulge of hair follicle
b. brain
c. lungs
d. intestine
e. bone marrow

9. Which of the following cells has no nucleus?
a. red blood cell
b. osteoblast
c. osteocyte
d. white blood cell

10. Which of the following is false about extracellular fluids?
a. it contains glucose
b. it contains amino acids and fatty acids
c. it has larger amounts of potassium than interstitial fluid
d. it contains CO2

11. Homeostasis is like cruise control, it must have:
a. a mean for adjustment
b. a set point
c. detectors to realize it needs adjustment
d. all of the above
e. none of the above

12. I went into the bookstore and noticed that I was going to have to fork out
nearly $200 dollars for my new physiology text book. Desperate for money I
was forced to donate some plasma A LOT of plasma in order to get my new book. This plasma is a subdivision of which major compartment.
a. intracellular compartment
b. epidermal compartment
c. median-basilic compartment
d. extracellular compartment

13. I was walking in the jungle on a wild safari and as I was admiring a spider
monkey swinging from branch to branch I found my self falling into a huge
pit of quicksand. As I was sinking I was thinking about my death and
realized, like many deaths I would die because:
a. my cells need oxygen to survive
b. my cells cant get the proper nutrition from sand
c. insufficient levels of ATP
d. your cells wont die until your heart stops

14. Sweating and shivering are an example of what?
a. positive feedback
b. negative feedback
c. hormonal imbalance
d. aging

15.Glands are derived from:
a. nervous tissue
b. connective tissue
c. muscular tissue
d. epithelial tissue

16. For the Halo 3 debut the news showed footage of people rushing into the store to get their copy. They focused in on a guy that was pacing back and forth dripping in sweat anxious to get his copy. Sweat is secreted by exocrine glands. This means his sweat:
a. is produced by epithelial cells
b. is a hormone
c. is secreted into a duct
d. is produced outside the body

17. The most imediate need for a cell is?
a. glucose
b. gas exchange
c. protein
d. fatty acids

To those of you who are writing notes: feel free to use material from the on-line physiology book made by prior classes of Provo College students. Here is the link to the homeostasis chapter. You can copy/paste any of this material, as it is free of copyrights.

Physiwiki World

flattail — Tue, 11 Aug 2009 19:56:12 CDT

Notes of current interest
The Online Resources lists several sites with animations and tutorials. For example, to better understand how neurons work check out this site.

Provo College Students: If you are looking for extra help with the wiki please contact Kari (razaelas), who will give tutorials.

WELCOME! This site is for anyone looking to learn or enhance their knowledge in Human Physiology. You are welcome to join and make any edits that you feel would be appropriate and help to improve this site.

Notes of current interest

The Online Resources lists several sites with animations and tutorials. For example, to better understand how neurons work check out this site.

Provo College Students: If you are looking for extra help with the wiki please contact Kari (razaelas), who will give tutorials.

Quick Links

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Here is a short video where Kevin introduces the site. Here is an even shorter video, captured using Jing. Notes and review questions have been created for every chapter that was covered during lectures to Provo College in 2007. Every page could be reorganized, added to, or enhanced. Please feel free to help at any time. To get started:

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Start editing! Add content, fix typos, improve questions, post links to online material, etc. For complete instructions on any editing procedure, visit the How To page.

In making notes, it may be worthwhile to re-watch the recorded lectures. Another resource is the online physiology book that prior classes made at wikibooks.org. All of the material in the online book is free of copyright, so if there is something you like you can copy/paste from it and modify it as you see fit.

There is a new page of Study Tips that may help you improve your study skills and test-taking strategies.

Online Resources

flattail — Wed, 04 Mar 2009 20:18:55 CST

If you find something in your web browsing that looks useful to physiology students, just list it here!

The resources associated with the book Essentials of Anatomy and Physiology are freely available here. Choose a chapter along the top, then you can select quizzes, animations, notes, etc. along the side. I particularly liked the case studies.

The Fox Fundamentals of Physiology website has several resources as well.
Neurobiology animations from Blackwell publishing.
Some more animations courtesy of Harvard.
Some amazing Molecular Movies that show details of cellular processes.

Nervous System

flattail — Mon, 02 Feb 2009 15:09:52 CST

Chapter Objectives

After studying this chapter, students should be able to . . . 1. describe the structure of a neuron and explain the functional significance of its principal regions. 2. classify neurons on the basis of their structure and function. 3. describe the locations and functions of the different types of supporting cells. 4. explain what is meant by the blood-brain barrier and discuss its significance. 5. describe the sheath of Schwann and explain how it functions in the regeneration of cut peripheral nerve fibers. 6. explain how a myelin sheath is formed. 7. define depolarization, repolarization, and hyperpolarization. 8. explain the actions of voltage-regulated Na+ and K+ channels and describe the events that occur during the production of an action potential. 9. describe the properties of action potentials and explain the significance of the all-or-none law and the refractory periods. 10. explain how action potentials are regenerated along a myelinated and a nonmyelinated axon. 11. describe the events that occur in the interval between the electrical excitation of an axon and the release of neurotransmitter. 12. describe the two general categories of chemically regulated ion channels, and explain how these operate using nicotinic and muscarinic ACh receptors as examples. 13. explain how ACh produces EPSPs and IPSPs, and indicate the significance of these processes. 14. compare the characteristics of EPSPs and action potentials. 15. compare the mechanisms that inactivate ACh with those that inactivate monoamine neurotransmitters. 16. explain the role of cyclic AMP in the action of monoamine neurotransmitters, and some of the actions of monoamines in the nervous system. 17. explain the significance of the inhibitory effects of glycine and GABA in the central nervous system. 18. list some of the polypeptide neurotransmitters, and explain the significance of the endogenous opioids in the nervous system. 19. discuss the significance of nitric oxide as a neurotransmitter. 20. explain how EPSPs and IPSPs can interact and discuss the significance of spatial and temporal summation and of presynaptic and postsynaptic inhibition. 21. describe the nature of long-term potentiation and discuss its significance.

A brain researcher discovers what it is like to have a stroke

The Nervous System: Neurons and Synapses

The Nervous System is composed of two different parts:
Central Nervous System which is composed of the Brain and the Spinal cord
Peripheral Nervous System is composed of the Cranial nerves and Spinal Nerves

Parasympathetic - "Rest and Digest"
Sympathetic - "Fight or Flight"

Homeostasis is maintained by an appropriate balance between sympathetic and parasympathetic activity.

Nerve- Any bundle of nerve fibers running to various organs and tissues of the body
Neuron- A cell specialized to conduct and generate electrical impulses and to carry information from one part of the brain to another.

Neuron is a single nerve cell; a nerve is a bundle of many nerve fibers (axons and dendrites of neurons) Neurons are responsible for integrating information received from the internal and external environment; they are specialized for excitability and conductivity and consist of a cell body, dendrites and an axon. There are three types of neurons in the body. We have sensory neurons, interneurons, and motor neurons. Neurons are a major class of cells in the nervous system and the functional unit of the nervous system (but they are outnumbered by glial cells).
Neurons are sometimes called nerve cells, though this term is technically imprecise, as many neurons do not form nerves. In vertebrates, neurons are found in the brain, the spinal cord and in the nerves and ganglia of the peripheral nervous system. Their main role is to process and transmit information.
Neurons have excitable membranes, which allow them to generate and propagate electrical impulses. Sensory neuron takes nerve impulses or messages right from the sensory receptor and delivers it to the central nervous system. A sensory receptor is a structure that can find any kind of change in it's surroundings or environment.

Each neuron can carry a signal in only one direction (from the cell body down the axon). They are long lived cells, having been in your body since before birth or in the few years after birth.
Neurons of the peripheral nervous system can be very long cells, since the cell body must reside in or near the central nervous system. Motor neurons of the PNS have short dendrites and their cell body resides in the spinal cord. They have a long axon that goes to the muscle or gland they innervate. Sensory neurons of the PNS have long dendrites going from the region they receive sensory input from to the basal ganglia next to the spinal cord (where their cell bodies are located). Sensory neurons have a short axon going into the spinal cord and synapsing with other neurons.

Check out the Mouse Party and other cool demonstrations about how drugs work! Test your response time by playing this game (try it at different times of day or after drinking caffeine!)

Types of Neurons

Structure of a neuron

Neurons have three different parts to them. They all have an axon, a cell body and dendrites. The axon is the part of the neuron that conducts nerve impulses. Axons can get to be quite long. When an axon is present in nerves, it is called a nerve fiber. A cell body has a nucleus and it also has other organelles. The dendrites are the short pieces that come off of the cell body that receive the signals from sensory receptors and other neurons.

Synapse:

Chemical synapses are specialized junctions through which the cells of the nervous system signal to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow the neurons of the central nervous system to form interconnected neural circuits.
Transmissions across the majority of synapses in the nervous system is one-way and occurs through the release of chemical neurotransmitters from the presynaptic axon endings called terminal boutons.

Myelin Sheath
Schwann cells contain a lipid substance called myelin in their plasma membranes. When schwann cells wrap around axons, a myelin sheath forms. There are gaps that have no myelin sheath around them; these gaps are called nodes of Ranvier. Myelin sheathes make excellent insulators. Axons that are longer have a myelin sheath, while shorter axons do not. The disease multiple sclerosis is an autoimmune disease where the body attacks the myelin sheath of the central nervous system.

Neuroglia- Support cells, also known as glial cells. They are more abundant than neurons. They do not transport messages.

Astrocytes, Oligodendrocytes, and Schwann cells
-Oligodendrocytes have extensions that form the myelin sheath around axons in the Central Nervous System. Nerve impulses travel faster along myelinated axons than unmyelinated axons (saltatorial conduction is the term to describe jumping from one node to another).

-Schwann cells perform the same function as oligodendrocytes, but are found in the peripheral nervous system. Instead of having extensions that wrap around axons, the entire cell wraps itself around and around.

-Astrocytes are most common in the brain. They have lots of small feet that go to capillaries and neurons.This is the cell in which all things must go through to get to the brain. They must perform this duty because the capillaries have tight junctions in which messages cannot be passed. This is what is called the blood brain barrier. Many drugs cannot enter the astrocytes. They must instead use a precursor drug. Astrocytes are found in the CNS.

In class we used the example of Dopamine which cannot pass the blood brain barrier, so instead you must use the precursor of L-dopa which can pass the "BBB" (blood brain barrier). The L-dopa then tells the brain to make dopamine.

Electrical Activity of Axons
The permeability of the axon membrane of sodium to potassium is regulated by gated channels.
-Resting membrane potential is -70 mV (voltage). This is sightly permeable to potassium and impermeable to sodium.
-An excess positive charge on the outside of the cell and the excess of the negative charge inside the cell collect close to the plasma membrane These exceeds charges are only a very small fraction of the total number of ions in and outside the cell.
-
A more in depth look at Electrical Activity of Axons

The Nerve Impulse

When a nerve is stimulated the resting potential changes. Examples of such stimuli are pressure, electricity. chemicals., etc. Different neurons are sensitive to different stimuli(although most can register pain). The stimulus causes sodium ion channels to open. The rapid change in polarity that moves along the nerve fiber is called the "ACTION POTENTIAL." This moving change in polarity has several stages: Depolarization The upswing is caused when positively charged sodium ions(Na+) suddenly rush through open sodium gates into a nerve cell.The membrane potential of the stimulated cell undergoes a localized change from-65 millivolts to 0 in a limited area. As additional sodium rushes in, the membrane potential actually reverses its polarity so that the outside of the membrane is negative relative to the inside. During this change of polarity the membrane actually develops a positive value for a moment(+40 millivolts). The change in voltage stimulates the opening of additional sodium channels (they are voltage-gated). This is an example of a positive feedback loop.
Repolarization (The down-swing) is caused by the closing of sodium ion channels and the opening of potassium ion channels. Release of positively charged potassium ions (K+) from the nerve cell when potassium gates open. Again, these are opened in response to the positive voltage--they are voltage gated. This expulsion acts to restore the localized negative membrane potential of the cell (about -65 or -70 mV is typical for nerves).
Refractory phase is a short period of time after the depolarization stage. Shortly after the sodium gates open they close and go into an inactive conformation. The sodium gates cannot be opened again until the membrane is repolarized to its normal resting potential. The sodium-potassium pump returns sodium ions to the outside and potassuim ions to the inside. During the refractory phase this particular area of the nerve cell membrane cannot be depolarized. This refractory area explains why action potentials can only move forward from the point of stimulation. Increased permeability of the sodium channel occurs when there is a deficit of calcium ions. when there is a deficit of calcium ions (Ca+2) in the interstitial fluid the sodium channels are activated (opened) by very little increase of the membrane potential above the normal resting level. The nerve fiber can therefore fire off action potentials spontaneously, resulting in tetany. Could be caused by the lack of hormone from parathyroid glands. Could be caused by hyperventilation, which leads to a higher pH, which causes calcium to bind and become unavailable. Speed of conduction. This area of depolarization/repolarization/recovery moves along a nerve fiber like a very fast wave. In nonmyelinated fibers, conduction is hundreds of times faster because the action potential only occurs at the nodes of Ranvier by jumping from node to node. This is called "saltatory" conduction. Damage to the myelin sheath by the disease can cause severe impairment of nerve cell function. Some poisons and drugs interfere with nerve impulses by blocking sodium channels in nerves. See discussion on drug at the end of this outline.

If you don't understand this a great illustrated site to look into... http://outreach.mcb.harvard.edu/animations/actionpotential.swf

All or none law

Muscle cells and neurons function on an all-or-none principle. Once the stimulus exceeds a certain threshold, the contraction or nerve impulse in that single cell will happen, and it will happen all the way. It's like when you play dominoes and you line them up and you tilt the first one only so far and not have it fall over, but once you pass the point of no return, they are going down, and all the others will fall down in a quick motion. This principle is fully dependent on those gated ion channels opening, letting sodium ions flood into the cell.

Acetylcholine as a neurotransmitter

Acetylcholine(ACh) is used as an excitatory neurotransmitter by some neurons in the CNS and by somatic motor neurons at the neuromuscular junction. At autonomic nerve endings, ACh may be either excitatory or inhibitory, depending on the organ involved.

The stimulatory effects on ACh on skeletal muscle cells is produced by the binding of ACh to nicotinic ACh receptors. Effects of ACh on other cells occur when ACh binds to muscarinic ACh receptors.

Chemically regulated Channels

The binding of a neurotransmitter to its receptor protein can cause the opening of ion channels through two different mechanisms. These two mechanisms can be illustrated by the actions of ACh on the nicotonic and muscarinic subtypes of the ACh receptors.

Ligand-Gated Channels

A neurotransmitter molecule is the ligand that binds to its specific receptor protein. Part of the protein has extracellular sites that bind to the neurotransmitter ligands, while part of the protein spans the plasma membrane and has a central ion channel.

The nicotinic ACh receptor can serve as an example of ligand-gated channels. Two of its five-polypeptide subunits contain ACh binding sites, and the channel opens when both sites bind to ACh. The opening of this channel permits the simultaneous diffusion of Na+ into and K+ out of the postsynaptic cell. The effects of the inward flow of Na+ predominate, however, because of its steeper electrochemical gradient. This produces the depolarization of an excitatory postsynaptic potential (EPSP)

Although the inward diffusion of Na+ predominates in an EPSP, the simultaneous outward diffusion of K+ prevents the depolarization from overshooting 0mV.

G-Protein-Coupled Channels

The muscarinic ACh receptors are formed from only a single subunit which can bind to one ACh molecule. Unlike the nicotinic receptors, these receptors do not contain ion channels. Binding of ACh (the ligand) to the muscarinic receptor causes it to activate a complex of proteins in the cell membrane known as G-Proteins. They are named because their activity is influenced by guanosine nucleotides.

There are 3 G-protein subunits
1-Alpha
2-Beta
3Gamma

In response to the binding of ACh to its receptor, the alpha subunit dissociates from the other two subunits, which stick together to form a beta-gamma complex. On the specific case, either the alpha subunit or the beta-gamma complex then diffuses through the membrane until it binds to an ion channel, causing the channel to open or close.

The binding of ACh to its muscarinic receptors indirectly affects permeability of K+ channels. This can produce hyperpolarization in some organs and depolarization in other organs.

Scientists have learned that it is the beta-gamma complex that binds to the K+ channels in the heart muscle cells and causes these channels to open. Which leads to the diffusion of K+ out of the postsynaptic cell. The cell the becomes hyperpolarized production an inhibitory postsynaptic potential (IPSP). Such an effect is produced in the heart for example, when autonomic nerve fibers synapse with pacemaker cells and slow the rate of beat.

In a smooth muscle cells of the stomach the binding of ACh to its muscarinic receptors causes a different type of G-protein alpha subunit to dissociate and bind to gated K+ channels. The binding of the G-protein subunit to the gated K+ channels causes them to close rather than open. The diffusion of K+ which occurs at an outgoing rate in the resting cell is reduced to below resting levels. The resting membrane potiential is maintained by a balance between cations flowing into the cell and cations following out a reduction in the outward flow of K+ produces a depolarization. This depolarization produced in these smooth muscle cells results in contraction of the stomach

Acetylcholinesterase (AChE)

The inactivation of ACh is achieved by means of an enzyme called acetylcholinesterase or AChE which is present on the postsynaptic membrane or immediately outside the membrane with its active site facing synaptic cleft.

Acetylcholine in the PNS

Somatic motor neurons form synapses with skeletal muscle cells (muscle fibers). At these synapes, or neuromuscular junctions, the postsynaptic membrane of the muscle fiber is known as a motor end plate. The EPSPs produced by ACh in the skeletal muscle fibers are often called end-plate potentials. Voltage-regulated channels produce action potentials in the muscle fiber, and these are reduced by other voltage-regulated channels along the muscle plasma membrane

If in any stage in the process of neuromuscular transmission is blocked, muscle weakness sometimes leading to paralysis and death may result

Autonomic motor neurons innervated cardiac muscle, smooth muscles in blood vessels and visceral organs, and glands. There are two classifications of autonomic nerves, sympathetic and parasympathetic. Most of the parasympathetic axons that innervate the effector organs use ACh as their neurotransmitter.

Neuroscience

Now that we have discussed individual components of the nervous system, you may want to learn more about neuroscience on a broader scale. Check out these links.

QUESTIONS

1. Which support cell creates the blood brain barrier?
a. Glial Cell
b. Neurons Cell
c. Schwann Cell
d. Satellite Cell
e. Astrocyte

2. When I was a kid my mother would yell at my brother for sniffing glue. She would tell him he would lose all his brain cells if he kept doing this. Was my mother correct?
a. no, cells re-grow
b. due to mitosis we do not need to worry about the amount of cells we have
c. we have an endless supply, so sniff away
d. brain cells are limited, she was correct
e. this was found true by brain cell studies.

3. When the child touched the hot stove the nerve impulse shot back up to the cell body through what?
a. Axon
b. Dendrite
c. Neuron
d. A and B the impulse was going back and forth at the same time

4. My aunt was diagnosed with multiple sclerosis which is a chronic, degenerating, remitting and relapsing disease that progressively destroys _______ in the Central Nervous System?
a. Schwann cells
b. microglia
c. oligodendrocyte cells
d. axons
e. astrocytes

5. Which of the following neurons are pseudounipolar?
a. autonomic motor neurons
b. somatic motor neurons
c. neurons in the retina
d. sensory neurons
e. all of the above

6. Which of the following may be produced by the action of nitric oxide?
a. dilation of blood vessels
b. constriction of blood vessels
c. erection of the penis
d. a and c only
e. all of the above

7. The supporting cells that form myelin sheaths in the peripheral nervous system are:
a. oligodendrocytes
b. satellite cells
c. Schwann cells
d. astrocytes
e. microglia

8. Where do dendrites transmit electrical impulses?
a. Away from the cell body
b. Towards the cell body
c. Around the cell body
d. Inside the cell body
e. All of the above

9. What is the nervous system divided into?
a. The central nervous system
b. The peripheral nervous system
c. Neurons
d. Cell body
e. a and b only

10. The absolute refractory period of a neuron:
a. occurs only during the repolarization phase
b. occurs only during the depolarization phase
c. is due to the high negative polarity of the neuron
d. occurs during depolarization and the first phase of repolarization

11. Which ion is responsible for the release of neurotransmitters during a synapse?
a. potassium ion
b. calcium ion
c. sodium ion
d. chlorine ion
e. negative ion

12. Which of the following is not true of the neuron?
a. composed of cell body, dendrites, and axon
b. long living
c. need individual neuron for every single muscle fiber
d. very interconnected, particularly in the brain
e. more inhibitory neurons than excitatory neurons

13. The most common cell in the brain is the:
a. astrocyte
b. schwann cell
c. microglia
d. oligodendrocyte

Chapter 13

flattail — Fri, 23 Jan 2009 18:01:41 CST

Blood, Heart, and Circulation

Composition of Blood -

-The human body makes about 2.5 million new blood cells per second. Which means that is how many are dying off in that amount of time.

So we make about five hundred million cells daily. CRAZY!!
-There are 60,000 miles of vessels throughout the human body (Australia and back four times) Your heart pumps this distance every minute.
-These blood vessels are flexible and will repair themselves when they leak.
-They carry gases, nutrients, hormones, wastes, etc, all together
-Capillaries are about one cell thick (the thickness allows for good diffusion for each cell across the membrane).

Blood is divided into two layers.
1) Formed Element

Red Blood Cells
White blood Cells (Mostly neutrophils and white blood cells are not as common as red blood cells)
Platelets

2) Plasma

Which is about 92 percent water, while the remaining 8 percent consists of various organic molecules and salts (sodium most common salt).

Three major plasma proteins help to maintain homeostasis:

Albumins (most common and is made by the liver. It is also the same protein that is in egg whites)
- Albumins play an important role in maintaining the bloods osmotic pressure needed to draw water from the surrounding tissue fluid into the capillaries. This action is needed to maintain blood volume and pressure.
Fibrinogen (the clotting protein)
- During the process of clot formation fibrinogen is converted into threads of fibrin.
Globulins (the antibodies) which is involved with immunity

-The difference between serum and plasma:
-* serum is plasma only without the clotting proteins (no fibrinogen is present)

Formed Elements of Blood, The formed elements of blood include two types of blood cells: erythrocytes, or red blood cells, and leukocytes, or white blood cells.

Red blood cell (erythrocyte) also known as "RBC's". RBC’s are formed in the myeloid tissue or most commonly known as red bone marrow, although when the body is under severe conditions the yellow bone marrow, which is also in the fatty places of the marrow, in the body will also make RBC’s. The formation of RBC’s is called erythropoiesis ( erythro / red; poiesis / formation). Red blood cells lose nuclei upon maturation, and take on a biconcave, dimpled, shape. They are about 7-8 micrometers in diameter. RBC's live about 120 days and do not self repair. Older erythrocytes are removed from the circulation by phagocytic cells in the liver, spleen, and bone marrow. RBC's contain hemoglobin which transports oxygen from the lungs to the rest of the body, such as to the muscles, where it releases the oxygen load.The hemoglobin gets it's red color from their respiratory pigments.

The main component of the RBC is hemoglobin (hemo / blood; globin / protein) protein which is about 25 million per cell. This is the protein substance of four different proteins: polypeptide globin chains that contain anywhere from 141 to 146 amino acids. Hemoglobin also is responsible for the cell’s ability to transport oxygen and carbon dioxide. In arterial blood, it is bright red because of a high concentration of oxyhemoglobin (the combination of oxygen and hemoglobin) in the red blood cells. In venous blood (the blood returning to the heart) it contains less oxygen, and is therefore a darker red than the oxygen-rich arterial blood. Carbon Monoxide forms with hemoglobin faster than oxygen, and stays formed for several hours making hemoglobin unavailable for oxygen transport right away. Also a red blood cell contains about 200 million hemoglobin molecules. If all this hemoglobin was in the plasma rather than inside the cells, your blood would be so "thick" that the heart would have a difficult time pumping it through. The thickness of blood is called viscosity. The greater the viscosity of blood, the more friction there is and more pressure is needed to force blood through. Iron travels in the blood to the bone marrow attached to a protein carrier called transferring.

The main function is the transportation of oxygen throughout the body and the ability of the blood to carry out carbon dioxide which is called carbamino – hemoglobin. Maintaining the balance of blood is important. The balance can be measured by the acid and base levels in the blood. This is called pH. Normal pH of blood ranges between 7.35-7.45; this normal blood is called Alkaline (less acidic then water). A drop in pH is called Acidic. This condition is also called Acidosis. A jump in pH higher then 7.45 is called "Alkalosis". To maintain the homeostasis (or balance,) the blood has tiny molecules within the RBC that help prevent drops or increases from happening.

A dietary deficiency in iron reduces the ability of the bone marrow to produce hemoglobin, and can result in iron-deficiency anemia. Anemia is an abnormally low hemoglobin concentration and or red blood cell count.

Hematocrit (HCT)
As well as a persons gender there are other factors that may influence hematocrit levels. High altitudes will increase the hematocrit levels because the higher elevation will cause an increase of red blood cells in order to compensate for the higher altitude. Hematocrit levels will also be effected by the amount one drinks, dehydration will cause an increase in the hematocrit levels.

normal hematocrit levels:
men: 42 - 53%
women: 36 - 48%
babies: 50 - 75%
(babies have a low oxygenated environment because their oxygenated blood mixes with their deoxygenated blood before it can reach all the cells)

-low hematocrit (anemia, blood loss, bone marrow failure, leukemia, liver cirrosis, etc.
-high hematocrit most likely due to dehydration

Homeostasis (Coagulation or Clotting)
Anticoagulants
Clotting of blood in test tubes can be prevented by the addition of sodium citrate, which bind to calcium ions. By this means, Ca2 levels in the blood that can participate in the clotting sequence are lowered and clotting is inhibited.

Homeostasis is the natural process of stopping blood flow or loss of blood following an injury. (hemo = blood; stasis = standing). It has three stages: (1) vascular spasm, vasoconstriction, or intense contraction of blood vessels, (2) formation of a platelet plug and (3) blood clotting or coagulation. Once the flow of blood has been stopped, tissue repair can begin.

Blood clots contain platelets and fibrin and usually trapped red blood cells that give the clot a red color. The clots that are formed in arteries, where blood flow is faster lack red blood cells and are usually gray. The platelet mass in the process of clot retraction forms a more compact and effective plug. Serum is fluid squeezed from the clot. Serum is plasma without fibrogen.

Intrinsic pathway produces clots in damaged blood vessels when collagen is exposed to plasma.
Extrinsic pathway is when a chemical is produced that creates a shortcut in the formation of fibrin.

Formation of a Platelet Plug: Within 20 seconds of an injury, coagulation is initiated. Contrary to popular belief, clotting of a cut on the skin is not initiated by air or drying out, but by platelets adhering to and activated by collagen in the blood vessels endothelium. The activated platelets then release the contents of their granules, which contain a variety of substances that stimulate further platelet activation and enhance the hemostatic process.
When the lining of a blood vessel breaks and endothelial cells are damaged, revealing collagen proteins in the vessel wall, platelets swell, grow spiky extensions, and start clumping together. They start to stick to each other and the walls of the vessel. This continues as more platelets congregate and undergo these same transformations. This process results in a platelet plug that seals the injured area. If the injury is small, a platelet plug may be able to form and close it within several seconds. If the damage is more serious, the next step of blood clotting will take place. Platelets contain secretory granules. When they stick to the proteins in the vessel walls, they degranulate, thus releasing their products, which include ADP (adenosine diphosphate), serotonin, and thromboxane A2.

A Blood Clot Forms: If the platelet plug is not enough to stop the bleeding, the third stage of homeostasis begins: the formation of a blood clot. First, blood changes from a liquid to a gel. At least 12 substances called clotting factors take part in a series of chemical reactions that eventually create a mesh of protein fibers within the blood. Each of the clotting factors has a very specific function. We will discuss just three of the substances here: prothrombin, thrombin, and fibrinogen. Prothrombin and fibrinogin are proteins that are produced and deposited in the blood by the liver.

Prothrombin: When blood vessels are damaged, vessels and nearby platelets are stimulated to release a substance called prothrombin activator, which in turn activates the conversion of prothrombin, a plasma protein, into an enzyme called thrombin. This reaction requires calcium ions.

Thrombin: Thrombin facilitates the conversion of a soluble plasma protein called fibrinogen into long insoluble fibers or threads of the protein fibrin.

Fibrin: Fibrin threads wind around the platelet plug at the damaged area of the blood vessel, forming an interlocking network of fibers and a framework for the clot. This net of fibers traps and helps hold platelets, blood cells and other molecules tight to the site of injury, functioning as the initial clot. This temporary fibrin clot can form in less than a minute, and usually does a good job of reducing the blood flow. Next, platelets in the clot begin to shrink, tightening the clot and drawing together the vessel walls. Usually, this whole process of clot formation and tightening takes less than a half hour.

Functions of Blood

Transport Oxygen, Carbon dioxide, Glucose, Ammonia, nutrients and Hormones
It is protection or defense (Immune system)
Heat regulation
Protection against bleeding (clotting)

All of the substances that are essential for cellular metabolism are transported by the circulatory system. Red blood or erythrocytes transport oxygen to the cells. In the lungs oxygen that is inhaled attaches to the blood molecules within the erythrocytes and is transported to the cells for aerobic respiration. Carbon dioxide that is produced by cell respiration is carried by the blood to the lungs to be exhaled.

The circulatory system protects against blood loss from injury and against foreign microbes or toxins that are introduced to the body. The clotting mechanism protects against blood loss when blood vessels are damaged.

The immune function of the blood is performed by the leukocytes (white blood cells) that protect against many disease causing agents (pathogens).

The Circulatory system contributes to both hormonal and temperature regulation. The blood carries hormones from their site of origin to the distant target tissues, where they perform a variety of regulatory functions. Temperature regulation is aided by the diversion of blood from deeper to more superficial cutaneous vessels or vice versa. When the temperature is high, diversion of blood from deep to superficial vessels helps to cool the body, and when the temperature is low, the diversion of blood from superficial to deeper vessels helps to keep the body warm.

The digestive system is responsible for the mechanical and chemical breakdown of food so that it can be absorbed through the intestinal wall into the blood and lymphatic vessels. The blood then carries these absorbed products of digestion through the liver and to the cells of the body.

Metabolic waste (like urea), excess water and ions, and other molecules not needed by the body are carried by the blood to the kidneys and excreted in the urine.

Gas Exchange

-Capillary exchange ( of all the blood vessels only capillaries can make the gas exchange)

- Pumping of heart sends blood out via the arteries to the capillaries where exchange takes place through capillary walls. Blood returns via the veins.
-Arterial blood contains more oxygen and nutrients than venous blood
-Venous blood contains more wastes, including carbon dioxide, than arterial blood.

-Blood capillaries
-Processes at work during capillary exchange.
-blood pressure
-diffusion (Oxygen, amino acids, and glucose diffuses out in the capillary and carbon dioxide, water, and wastes diffuse in the capillary)
=there is no active transport in capillaries because the thickness of the capillary makes it easy for molecules to get in and out)
-osmotic pressure
-Arterial end of capillary
-When arterial blood enters tissue capillaries:
-Bright red due to oxygen levels.
-rich in dissolved nutrients
-Blood pressure is higher than osmotic pressure
-Water and nutrients exit capillaries
-Venous end of capillary
-Blood pressure is reduced because capillaries have a greater
cross-section compared to blood vessels that enter and leave the
capillaries
-No reduction of osmotic pressure
-Water tends to enter the capillary

Oxygen (O2) is the most immediate need of every cell and is carried throughout the body by the blood circulation. Oxygen is used at the cellular level as the final electron acceptor in the electron transport chain (the primary method of generating ATP for cellular reactions). Oxygen is carried in the blood bound to hemoglobin molecules within red blood cells. Hemoglobin binds oxygen when passing through the alveoli of the lungs and releases oxygen in the warmer, more acidic environment of bodily tissues, via simple diffusion.
Carbon dioxide (CO2) is removed from tissues by blood and released into the air via the lungs. Carbon dioxide is produced by cells as they undergo the processes of cellular respiration (particularly the Kreb's Cycle). The molecules are produced from carbons that were originally part of glucose. Most of the carbon dioxide combines with water and is carried in the plasma as bicarbonate ions. An excess of carbon dioxide (through exercise, or from holding ones breath) quickly shifts the blood pH to being more acidic (acidosis). Chemoreceptors in the brain and major blood vessels detect this shift and stimulate the breathing center of the brain (the medulla oblongata). Hence, as CO2 levels build up and the blood becomes more acidic, we involuntarily breathe faster, thus lowering CO2 levels and stabilizing blood pH. In contrast, a person who is hyperventilating (such as during a panic attack) will release too much CO2 and the blood will become too alkaline (alkalosis).

3 basic causes of shock

1. Pump failure, due to heart disease
2. Vessel failure
3. Content failure

SEPTIC SHOCK
refers to a dangerously low blood pressure that may result from sepsis, or infection. This can occur through the action of a bacterial lipopolysaccharide called endotoxin. The mortality associated with septic shock is presently very high, estimated at 50% to 70%. According to recent information, endotoxin activates the enzyme nitric oxide in synthase within macrophages--cells that play a important role in the immune response. Nitric oxide synthase produces nitric oxide, which promotes vasodilation and, as a result, a fall in blood pressure. Septic shock has recently been treated effectively with drugs that inhibit the production of nitric oxide. Basically not only can the infection itself kill you, but the treatment could also kill you due to the fact that when you kill the bacteria it will release toxins that could kill you.

Blood Typing
Blood is classified into different types (A, B, AB, or O) according to the absence or presence of certain antigens on the surface of a persons red blood cells.
Type A blood has A antigens
Type B blood has B antigens
Type AB has both A and B antibodies
This makes it so if you have type A blood you can only receive type A blood so your body will not recognize anything foreign and try to fight it. An individual with type B blood does not produce antibodies to B antigen because that antigen is recognized as "self." This person will have antibodies to A antigen even if this person has never been exposed to type A blood.
Type O has neither antigen in it which makes it the universal donor because any anti-A or anti-B antibodies that may be present in the recipient will find no target on the type O donor cell

Review Questions

1. Which processes are at work during capillary exchange?
a. Blood Pressure
b. Diffusion
c. Osmotic Pressure
d. All of the above

2. Arterial blood contains more:
a. wastes
b. oxygen
c. nutrients
d. a and b only
e. b and c only

3.If you were to measure the blood vessels in your body, how many miles would it stretch?
a.100,000 miles
b.2,000,000 miles
c.60,000 miles
d.6,000 miles
e.There is no way to measure blood vessels

4. How thick would you say your blood capillaries are?
a.1 inch thick
b.3 cells thick or bigger
c.1/2 an inch thick
d.1 cell thick or smaller so your blood cells would have to squeeze in
e.As thick as a pencil

5. Where do we get most of our Vitamin K?
a. liver
b. bacteria
c. eating leafy green veggies
d. taking vitamin supplements
e. all of the above

6. As I was mountain climbing my body would produce more red blood cells as I reached higher elevations due to which hormone?
a. thrombopoietin
b. cytokines
c. erythropoietin
d. megakaryocytes

7. Which of the plasma proteins are responsible for the osmotic pressure in the arteries and is produced by the liver?
a. Albumin
b. Globulins
c. Fibrinogens
d. None of the above

8. What is the approximate life span of an erythrocyte?
a. 3 days
b. 4 months
c. not known
d. 1 year

9. How many blood cells do you make per second?
a. 25,000
b. 2.5 billion
c. 2.5 million
d. 2500
e. none of the above

10. Plasma contains:
a. Water
b. Na++
c. Mg++
d. K+
e. All of the above

11. The mineral need for chemical clotting is:
a. sodium
b. calcium
c. iron
d. potassium

12. The function of erythroprotien is to:
a. decrease RBC production
b. Increase RBC production
c. Decrease all blood cell production
d. increase all blood cell production

13.Taking aspirin every day can reduce the risk of heart disease because:
a. it is a powerful vasodilator
b. it blocks pain receptors in heart tissue
c. it loosens plaque on arterial walls
d. it prevents platelet clumping

14. A hematocrit measures percentage of:
a. White blood cells
b. Plasma
c. Platelets
d. Red blood cells

15. Which type of blood is the universal donor?
a. Type A
b. Type B
c. Type C
d. Type AB
e. Type O

16. An individual with type AB blood
a. is considered a universal blood donor.
b. is considered a universal blood recipient.
c. produces antibodies to the B antigen.
d. produces antibodies to the A antigen.
e. is Rh-positive.

17. All of the following are blood cells except:
a. megakaryocyte
b. erythrocytes
c. leukocytes
d. thrombocytes

18. Which of the following about plasma is not true?
a. 91% water
b. carries body heat
c. transports hormones
d. insoluble

Chapter 11: Endocrine Glands

flattail — Fri, 09 Jan 2009 00:50:38 CST

Endocrine System (a review) The endocrine system consists of glands which secrete hormones into the bloodstream. Each hormone has an effect on one or more target tissues. In this way the endocrine system regulates the metabolism and development of most body cells and body systems. To be more specific, the Endocrine system has sex hormones that can activate sebaceous glands, development of mammary glands, alter dermal blood flow and release lipids from adipocytes and MSH can stimulate melanocytes on our skin. Our bone growth is regulated by several hormones, and the endocrine system helps with the mobilization of calcitonin and calcium. In the muscular system hormones adjust muscle metabolism, energy production, and growth. In the nervous system hormones affect neural metabolism, regulate fluid/electrolyte balance and help with reproductive hormones that influence CNS development and behaviors. In the Cardiovascular system we need hormones that regulate the production of RBC's, elevate and lower blood pressure. Hormones also have anti-inflammatory affects as well as stimulates the lymphatic system. In summary, the endocrine system has a regulatory effect on basically every other body system.

Here is a great (kinda boring) video on the different glands in the body as well as what each gland does. Have fun: http://www.youtube.com/watch?v=IVUG74D1BzQ

Endocrine Glands and Hormones
Hormones are regulatory molecules secreted into the blood by endocrine glands. Chemical categories of hormones include steroids, amines, polypeptides, and glycoproteins. Interactions between the various hormones produce effects that may by synergistic.

Endocrine Glands – lack the ducts that are present in exocrine glands. The endocrine glands secrete their products, which are biologically active molecules called hormones, into the blood. The blood carries the hormones to target cells that contain specific receptor proteins for the hormones, and which therefore can respond in a specific fashion to them.

Chemical classification of Hormones
Hormones secreted by different endocrine glands vary widely in chemical structure. All hormones, however, can be divided into a few chemical classes.
In terms of their actions in target cells, hormone molecules can be divided into those that are polar, and therefore water-soluble, and those that are nonpolar, and thus insoluble in water. Since the nonpolar hormones are soluble in lipids, they are often referred to as lipophilic hormones. Unlike the polar hormones, which cannot pass through plasma membranes, lipophilic hormones can gain entry into their target cells. These lipophilic hormones include the steroid hormones and thyroid hormones.

Amines – These are hormones derived from the amino acids tyrosine and tryptophan. They include the hormones secreted by the adrenal medulla, thyroid, and pineal glands. Some are polar (most) and some are nonpolar.
Polypeptides and Proteins – Polypeptide hormones generally contain less than 100 amino acids; an example is antidiuretic hormone. These are always polar (a chain of amino acids)
Glycoproteins – These molecules consist of a long polypeptide bound to one or more carbohydrate groups. Examples are follicle-stimulating hormone and luteinizing hormone.
- Amines, Polypeptides and Glycoproteins will utilize a secondary messenger system. a secondary messenger system is a method of cellular signalling where the signalling molecule does not enter the cell, but rather utilizes a cascade of events that transduces the signal into a cellular change
Steroids – These are lipids derived from cholesterol. They include the hormones testosterone, estradiol, progesterone, and cortisol. (non polar, they pass through the cell membrane and meet up with a receptor in the nucleus or just outside in the cytoplasm)

Hormone: A substance, usually a peptide or steroid, produced by one tissue and conveyed by the bloodstream to another to effect physiological activity, such as growth or metabolism.A chemical produced in one part of the body and released into the blood to trigger or regulate particular functions of the body. For example, insulin is a hormone made in the pancreas that tells other cells when to use glucose for energy.

Endocrine glands: Glands that produce and secrete hormones into the blood or lymph systems, including the thyroid, parathyroid, hypothalamus, pineal, pituitary, adrenal, islets of Langerhans in the pancreas, and the gonads (testes and ovaries). The effects of these hormones may affect one organ or tissue, or the entire body.

Exocrine Glands: Glands which secrete substances through ducts to surrounding surfaces. Includes sweat, salivary and tear glands, as well as the mucous glands in the digestive, respiratory, and genitourinary systems. These glands are greatly affected in CF. Their ducts may be obstructed by mucus.

Mechanisms of Hormone Action

I. Steroid and thyroid hormones enter their target cells and bind to receptor proteins.

Thyroid hormones attach to chromatin-bound receptors located in the nucleus.

Steroid hormones bind to cytoplasmic receptor proteins and translocate to the nucleus.

Attachment of the hormone receptor protein complex to the cromatin activates genes and thereby stimulates RNA and protein synthesis.

II. Polar hormones bind to receptor proteins on the outer surface of the target cell membrane, indirectly activating a specific enzyme in the cell membrane.

In the case of some hormones, activation of adrenylate cyclase occurs, resulting in the intracellular production of cyclic AMP.

Cyclic AMP activates a cytoplasmic enzyme called protein kinase. Protein kinase phosphorylates specific enzyme protein and thereby changes the metabolism of the target cell for those hormones that use cAMP as a second messenger.

In the case of other hormone actions, the enzyme phospholipase C is activated in the cell membrane, causing the release of inositol triphosphate into the cell.

Inositol triphosphate stimulates the release of Ca++ from the endoplasmic reticulum of the target cell.

Ca++ binds to regulatory proteins, such as calmodulin, that can influence the metabolism of the target cell.

PITUITARY GLAND

I The pituitary gland secretes eight hormones.

A The anterior pituitary secretes growth hormone, thyroid-stimulating hormone, adrenocorticotripic hormone, folicle-stimulating hormone, lutienizing hormone and prolactin.

B The posterior pituitary releases antidiuretic hormone and oxytocin, both of which are produced in the hypothalamus and transported to the posterior pituitary by the hypothalomo-hypophyseal tract.

II The release of posterior pituitary hormones is controlled by reflexes.

III Secretions of the anterior pituitary are controlled by hypothalamic hormones that stimulate or inhibit these secretions.

A These hormones are carried to the anterior pituitary by the hypothalamo-hypophyseal portal system.

IV Secretions of the anterior pituitary are also regulated by the feedback exerted by target gland hormones.

V Higher brain centers, acting through the hypothalamus, can influence pituitary secretions.

*Pituitary Gland: roughly size of a pea. Anterior and posterior secrete different hormones. Pituitary is under control of the hypothalamus. It is called the master gland because it influences so many other glands. Hypothalamus should be called the master gland because it controls the Pituitary Gland.

Hormones of the Posterior Pituitary Gland:

Antidiuretic Hormone (AKA. ADH or Vasopressin)
Functions:

Increases water reabsorption by the kidney tubules (water returns to the blood)
Decreases sweating
Causes vasoconstriction (in large amounts)

Regulation of Secretion:

Decreased water content in the body (alcohol inhibits secretion)

Oxytocin
Functions:

Promotes contraction of myometrium of uterus (labor)
Promotes release of of milk from mammary glands

Regulation of secretion:

Nerve impulses from hypothalamus, the result of stretching of cervix or stimulation of nipple
Secretion from placenta at end of gestation--- the stimulus is unknown

Hormones of the Anterior Pituitary Gland:

Growth Hormone (GH)
Functions:

Increases rate of mitosis
Increases amino acid transport in to cells
Increases rate of protein synthesis
Increases use of fats for energy

Regulation of Secretion:

GHRH (hypothalamus) stimulates secretion
GHIH---somatostatin (hypothalamus) inhibits secretion

Thyroid-Stimulating Hormone
Functions:

Increases secretion of thyroxine and T3 by thyroid gland

Regulation of Secretion:

TRH (hypothalamus)

Adrenocorticotropic Hormone (ACTH)
Functions:

Increases secretion of cortisol by the adrenal cortex

Regulation of Secretion:

CRH (Hypothalamus)

Prolactin
Functions:

Stimulates milk production by the mammary glands

Regulation of secretions:

PRH (hypothalamus) stimulates secretion
PIH (hypothalamus) inhibits secretion

Follicle-Stimulating Hormone (FSH)
Functions in Women:

Initiates growth of ova in ovarian follicles
Increases secretion of estrogen by follicle cells

Functions in Men:

Initiates sperm production in the testes

Regulation of Secretion:

GnRH (hypothalamus) stimulates secretion
Inhibin (ovaries or testes) inhibits secretion

Luteinizing Hormone (LH) (ICSH)
Functions in Women:

Causes ovulation
Causes the ruptured ovarian follicle to become the corpus luteum
Increases secretion of progesterone by the corpus luteum

Functions in Men:

Increases secretion of testosterone by the interstitial cells of the testes

Regulation of Secretion:

GnRH (hypothalamus)

AUTOCRINE & PARACRINE REGULATION
1.Autocrine regulators are produced and act within the same tissue of an organ, whereas paracrine regulators are produced within one tissue and regulate a different tissue of the same organ.Both types are local regulators-they do not travel in the blood.

2.Prostaglandins are special twenty-carbon-long fatty acids produced by many different organs.They usually have regulatory functions within the organ in which they are produced.

Diseases of the Thyroid

Thyroid-stimulating hormone (TSH) from the anterior pituitary stimulates the thyroid to secrete thyroxine; however, it also exerts a trophic (growth stimulating) effect on the thyroid. This effect is evident in people who develop an iodine-deficiency goiter, an abnormal growth of the thyroid gland. With the lack of adequate iodine in the diet it interferes with the negative feedback control of TSH secretion, resulting in the formation of an endemic goiter.

Graves disease is a thyroid disorder characterized by goiter, exophthalmos, "orange-peel" skin, and hyperthyroidism (has excessive thyroxine secretion).

Because of its stimulation of protein synthesis, children need thyroxine for body growth and, most importantly, for th proper development of the central nervous system. The need for thyroxine is particularly great when the brain is undergoing its greatest rate of development – from the end of the first trimester of prenatal life to 6 months after birth. Hypothyroidism during this time may result in cretinism. Unlike people with dwarfism, who have inadequate secretion of growth hormone from the anterior pituitary, people with cretinism suffer severe mental retardation.

How Your Thyroid Works "A delicate Feedback Mechanism"

Your thyroid gland is a small gland, normally weighing less than one ounce, located in the front of the neck. It is made up of two halves, called lobes, that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue, known as the isthmus.

The thyroid is situated just below your "Adams apple" or larynx. During development (inside the womb) the thyroid gland originates in the back of the tongue, but it normally migrates to the front of the neck before birth. Sometimes it fails to migrate properly and is located high in the neck or even in the back of the tongue (lingual thyroid) This is very rare. At other times it may migrate too far and ends up in the chest (this is also rare).

The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the blood stream and are transported throughout the body where they control metabolism (conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of their metabolism. The normal thyroid gland produces about 80% T4 and about 20% T3, however, T3 possesses about four times the hormone "strength" as T4.

The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain (shown here in orange). When the level of thyroid hormones (T3 & T4) drops too low, the pituitary gland produces Thyroid Stimulating Hormone (TSH) which stimulates the thyroid gland to produce more hormones. Under the influence of TSH, the thyroid will manufacture and secrete T3 and T4 thereby raising their blood levels. The pituitary senses this and responds by decreasing its TSH production. One can imagine the thyroid gland as a furnace and the pituitary gland as the thermostat. Thyroid hormones are like heat. When the heat gets back to the thermostat, it turns the thermostat off. As the room cools (the thyroid hormone levels drop), the thermostat turns back on (TSH increases) and the furnace produces more heat (thyroid hormones).

The pituitary gland itself is regulated by another gland, known as the hypothalamus (shown in our picture in light blue). The hypothalamus is part of the brain and produces TSH Releasing Hormone (TRH) which tells the pituitary gland to stimulate the thyroid gland (release TSH). One might imagine the hypothalamus as the person who regulates the thermostat since it tells the pituitary gland at what level the thyroid should be set.

Pancreas and Other Endocrine Glands

Beta cells in the islets secrete insulin, and alpha cells secrete glucagon.

Insulin lowers blood glucose and stimulates the production of glycogen, fat, and protein.
Glucagon raises blood glucose by stimulating the breakdown of liver glycogen. It also promotes lipolysis and the formation of keytone bodies.
The secretion of insulin is stimulated by a rise in blood glucose following meals. The secretion of glucagon is stimulated by a fall in blood glucose during periods of fasting.

The pineal gland, located on the roof of the third ventricle of the brain, secretes melatonin.

Melatonin secretion is regulated by the suprachiasmatic nucleus of the hypothalamus, which is is the major center for the control of circadian rhythms.
Melatonin secretion is highest at night, and this hormone has a sleep-promoting effect. In many species, it also has an antigonadotropic effect and may play a role in timing the onset of puberty in humans although this is as yet unproven.

The thymus is the site of T cell lymphocyte production and secretes a number of hormones that may help to regulate the immune system.

The gastrointestinal tract secretes a number of hormones that help to regulate digestive functions.

The gonads secrete sex steroid hormones.

Leydig cells in the interstitial tissue of the testes secrete testosterone and other androgens.
Granulosa cells of the ovarian follicles secrete estrogen.
The corpus luteum of the ovaries secretes progesterone, as well as estrogen.

The placenta secretes estrogen, progesterone, and a variety of polypeptide and protein hormones that have actions similar to some anterior pituitary hormones.

In the News

Did you know that almost all the research on stress has been conducted with men and that recent studies have found that women respond to stress in fundamentally different ways than men? Rather than simply "fight or flight," a woman's stress response may be to "tend and befriend." Read more about it here.

Question Review
1. What year was the first hormone discovered?
a. 1910
b. 1898
c. 1849
d. 1902
e. 1906

2. When you are dehydrated, your body will produce more ________ to conserve ____________.
a. ADH, water
b. TSH, iodine
c. oxytocin, water
d. water, MSH
e. none of the above

3.Steroid hormones are secreted by ___________.
a. the adrenal cortex
b. the gonads
c. the thyroid
d. both a and b
e. both b and c

4. Which is not apart of the endocrine system?
a. thyroid
b. pancreas
c. pituitary
d. brain

5. Why does insulin need to be given as a shot?
a. so the proteins can get into the blood stream
b. cause the insulin get though the body faster
c. because if taken as a pill the body will digest the insulin before it makes it to the blood stream.
d. both a and c

6. A_________hormone binds to a receptor within the target cell.
a. nonsteroid
b. cAMP
c. steroid
d. adenylate cyclase

7. The hormone properly called _______is also commonly known as adrenaline.
a. epinephrine
b. aldosterone
c. phospholipase c
d. oxytocin

8. All hormones can be divided into four chemical classes, they are.
a. Leptin, Aldosterone, Glucagon, Epinephrine
b. Amines, Polypeptides and proteins, Glycoproteins and Steroids
c. Melatonin, Oxytocin, Somatomedins and Glucocorticois
d. None of the above

9. What disease results from hyposecretion of GH ( in a child )?
a. dwarfism
b. cretinism
c. graves' disease
d. goiter
e. all of the above

10. Which is not produced in the anterior lobe of the Pituitary Gland?
a. growth hormone
b. prolactin
c. luteinizing hormone
d. Oxytocin
e. none of the above

11. Which disease causes fatigue, weight gain, hair loss and dry skin?
a. hyperkalemia
b. pancreatitis
c. cushings syndrome
d. hypothyroidism
e. all of the above

12. This gland is often called the master gland.
a. thymus
b. pituitary
c. thyroid
d. parathyroid
e. none of the above

13. Which of the following are considered Endocrine glands?
a. Pineal
b. Pituitary
c. islets of Langerhans
d. none of the above
e. all of the above

14. How many hormones does the pituitary gland secrete?
a. 8
b. 5
c. 10
d. 3
e. 9

Autonomic Nervous System

flattail — Tue, 06 Jan 2009 14:50:38 CST

The AutonomicNervous System

Chapter 9

Check out this link! Todays lecture made simple! The Autonomic Nervous System (Just ignore the Enteric System!)

The Autonomic Nervous System

• Regulate activity of smooth muscle, cardiac muscle & certain glands
• Structures involved – general visceral afferent neurons – general visceral efferent neurons – integration center within the brain
•Receives input from limbic system and other regions of the cerebrum

Autonomic versus Somatic NS

• Somatic nervous system – consciously perceived sensations – excitation of skeletal muscle – one neuron connects CNS to organ
• Autonomic nervous system – unconsciously perceived visceral sensations – involuntary inhibition or excitation of smooth muscle, cardiac muscle or glandular secretion – two neurons needed to connect CNS to organ
• preganglionic and postganglionic neurons
-Autonomic motor neurons have cell bodies in the CNS and synapses with another neuron in an autonomic ganglion.
-a ganglion is a collection of cell bodies outside the CNS
-Thus, there is a preganglionic neuron and a postganglionic neuron
-it is the postganglionic neuron that synapses with the target tissue.

Autonomic system: has two divisions
1. Sympathetic-- fight or flight
2. Parasympathetic--rest and digest
These two often have opposite reactions. Cranial nerves and spinal nerves are part of the peripheral system.

Divisions of the PNS:
* Motor neurons of both divisions have the cell body in CNS(brain and spinal cord)
* Can be either somatic or autonomic
** Somatic motor neurons innervate skeletal muscles
** Autonomic neurons innervate organs we don't have conscious control over (cardiac muscle, smooth muscle, and glands)

Parasympathetic system: The main nerve is the Vagus nerve. It is involved in swallowing, speech, liver, spleen, small and large intestines, heart, etc.

• Notice that the ANS pathway is a 2 neuron pathway while the Somatic NS only contains one neuron.

ANS Neurotransmitters

* Classified as either cholinergic or adrenergic neurons based upon the neurotransmitter released

Adrenergic

Cholinergic

Acetylcholine (ACh)

Acetylcholine is a primary neurotransmitter. - It is used by some neurons in the brain -It is used by ALL SOMATIC MOTOR NERVES OF THE PNS -It is used as the neurotransmitter by all preganglionic neurons of the ANS. -It is used by most postganglionic neurons of the Parasympathetic division of the ANS The contraction of a muscle uses Acetylcholine. ACh is an Excitatory (responds to nicotine) -when it binds to nicotine receptors and is sympathetic. ACh is an Inhibitory ( responds to muscarine )- when it binds to muscarinic receptors and is parasympathetic.
Examples of blocking ACh receptors are: The muscarinic effects of ACh are specifically inhibited the drug ATROPINE,

derived from the deadly nightshade plant ( Atropa belladonna ). Indeed, extracts of this plant were used by women during the Middle Ages to dilate their pupils ( atropine inhibits parasympathetic stimulation of the iris ). This was thought to enhance their beauty ( in Italian, bella means beautiful, donna means woman) Atropine is used clinically today to dilate the pupils during eye examinations.
The drug Curare- relaxes the muscle ( blocks the nicotinic receptors) and could cause you to die, however if you were given ventilation you would recover. It is a poison that belongs in the tomato family.
AChe is a nerve gas, your body will contract till you die.
Nerve gas- Inhibits ACHestaraes. You die from spastic paralysis, steady and prolonged involuntary contraction of the muscles contracted.

Cholinergic Neurons and Receptors

• Cholinergic neurons release acetylcholine from preganglionic neurons & from parasympathetic postganglionic neurons. • Excites or inhibits depending upon receptor type and organ involved Cholinergic receptors • Nicotinic receptors are found on dendrites & cell bodies of autonomic NS cells and at NMJ. Acetylcholine is excitatory when it bonds to these receptors. (also responds to Nicotine) • Muscarinic receptors are found on plasma membranes of all parasympathetic effectors. Acetylcholine is inhibitory when it binds to these receptors. (named because they also respond to muscarine, a drug from certain mushrooms)

Adrenergic Neurons and Receptors

• Adrenergic neurons release norepinephrine (NE)

What else is used as a transmitter?
Post ganglionic sympathetic neurons release Norepinephrine as a neurotransmitter
The receptors are termed "adrenegic"
*Norepinephrine released by sympathetic neurons, or epinephrine released by the adrenal medulla will stimulate the heart, dilate pupils and increase respiration

Reflex Arc

The reflex arc is a somatic motor neuron. Why? because is goes to a skeletal muscle. It has a cell body in the central nervous system, although it is part of the peripheral nervous system. The sensory neuron goes to a doral root ganglion which then goes to the cell body in the CNS and then goes to a motor neuron that goes straight to the target tissue.

The picture shows the central nerves system if you look on the left of the diagram you will see the Vagus nerve. The Vagus nerve is also called the pneumogastric nerve or the cranial nerve its the only nerve that starts in the Brain stem. the vagus nerve goes from the brain to the abdomen. All parts of the body controlled by the Vagus nerve are automatic nerves which we don't control, happens automatically like slow heart beat .

Chapter review questions

1. Where can you find muscarinic receptors?

a. on smooth muscles
b. on cardiac muscle cells
c. on glands
d. in parts of the brain
e. all of the above

2.Ganglia that can be seen alongside the spinal cord are not part of the sympathetic division?
a. True
b. False

3. The group of pharmaceutical chemists that made Viagra came from which country?

a. USA
b. France
c. Russia
D. England
E. Mars

4. Somatic motor neurons have cell bodies located ____ the CNS that project axons only to ____; and are usually under ____ control.

a. outside; skeletal: involuntary
b. inside; the viscera; voluntary
c. inside; the viscera ; involuntary
d. inside; skeletal muscle; voluntary

5. Which of the following statements about parasympathetic neurons is true?

a. The nerve fibers are contained in spinal nerves.
b. They synapse in terminal ganglia, either next to or within the organs innervated.
c. They originate in thoracic and lumbar regions of the spinal cord.
d. Postganglionic fibers are usually longer than those of sympathetic neurons.

6. The drug muscarine, derived from some poisonous mushrooms stimulates all of the following cholinergic receptors, except those receptors in

	a.	the heart.
	b.	the neuromuscular junction of skeletal muscle fibers.
	c.	the digestive system.
	d.	most target organs of postganglionic parasympathetic nerve fibers.

7. In general, parasympathetic activation will produce effects that are __________ to those produced by activation of sympathetic neurons.

	a.	similar, agonistic
	b.	opposite, antagonistic
	c.	complimentary
	d.	synergistic

8. Which of the following target tissues receive acetylcholine when the sympathetic division is stimulated?

	a.	sweat glands
	b.	salivary glands
	c.	smooth muscle of the GI tract
	d.	heart

9.The "fight or flight" response is the term used to describe activation of the ____.

	a.		PANS
	b.		SANS
	c.		somatic motor
	d.		CNS

Interactions between Cells & the Extracllular Enviroment

flattail — Tue, 06 Jan 2009 14:49:28 CST

CELL COMMUNICATIONS

Extracellular Environment

The extracellular environment surrounding cells consists of a fluid compartment, in which molecules are dissolved, and a matrix of polysaccharides and proteins that give form to the tissues. Interactions between the intracellular and extracellular environment occur across the plasma membrane.

Body Fluids
The water content of the body is divided into two compartments. Approximately 60 percent of the total body water is contained within the cells, in the interacellular compartment. The remaining 33 percent of total body water comprises the extracellular compartment. About 20 percent of this extracellular fluid is contained within the vessels of the cardiovascular system, where it comprises the fluid portion of the blood, or blood plasma.

Extracellular Matrix
The cells that comprise the organs of our body are embedded within the extracellular material of connective tissues. This material is called the extracellular matrix, and it consists of protein fibers collagen and elastin, as well as gel-like ground substance. The interstitial fluid referred to previously exists primarily in the hydrated gel of the ground substance. This is like glue! Cells will stick together.

Categories of Transport Across the Plasma Membrane
Passive transport is the net movement of molecules and ions across a membrane from higher to lower concentration (down a concentration gradient); it does not require metabolicenergy. Passive transport includes simple diffusion, osmosis, and facilitated diffusion.

Active transport is net movement across a membrane that occurs against a concentration gradient (to the region of higher concentration). Active transport requires the expenditure of metabolic energy (ATP) and involves specific carrier proteins. This kind of transport takes energy, because it is moving from a low to a high concentration.

Not all molecules can pass through the cell membrane, amino acids, DNA, nucleic acids. Others such as gas and water molecules pass through quickly.

Permeable- passable; allowing fluid to penetrate or pass through it.
Semipermeable- Permitting passage of only certain molecules. (example: Squirrel on the screen door)

Diffusion and Osmosis

Simple diffusion, or diffusion, is the net movement of substances from an area of higher concentration to an area of lower concentration. This movement occurs as a result of the random and constant motion characteristic of all molecules, (atoms or ions) and is independent from the motion of other molecules. Since, at any one time, some molecules may be moving against the gradient and some molecules may be moving down the gradient, although the motion is random, the word "net" is used to indicate the overall, eventual end result of the movement. To stop the molecules you would need to freeze them.

Facilitated diffusion is the diffusion of solutes through channel proteins in the plasma membrane. Water can pass freely through the plasma membrane without the aid of specialized proteins.

Osmosis is the diffusion of water molecules through a selectively permeable membrane. When water moves into a body by osmosis, hydrostatic pressure or osmotic pressure may build up inside the body Interactions between Cells and the extracellular environment

Tonicity is used to describe the effect of a solution on the osmotic movement of water. For example, if an isosmotic glucose or saline solution is separated from plasma by a membrane that is permeable to water, but not glucose or NaCl, osmosis will not occur. In this case the solution is said to be isotonic to plasma. A 0.3 m glucose solution, which is 0.3sm, or 300 milliosmolal (300 mOsm), has the same osmolality and osmotic pressure as plasma. The same is true of a 0.12 m NaCl solution, which ionizes to produce a total concentration of 300 mOsm. Both of these solutions are used intravenous infusions, labeled 5% dextrose (5g of glucose per 100ml, which is 0.3m) and normal saline (0.9g of NaCl per 100 ml, which is 0.12 m). Since 5% dextrose and normal saline have the same osmolality as plasma, they are said to be isomatic to plasma.

Isotonic-a solution having the same total solute concentration, osmolality, and osmotic pressure as the solution with which it is compared. A solution with the same solute concentration and osmotic pressue as plasma.

Hypotonic- Water enters the cell, and can cause the cell to burst.

Hypertonic-When cells are place in hypertonic solution (such as salt water) which contains osmotically active solutes at a higher osmolality and osmotic pressure then the plasma, the cells will shrink, the water within the cell is being pulled out. Sodium-Potassium pump (Na+ - K+)

Uses ATP to pump 3 Na+ out of the cell and 2 K+ into the cell.
Used to conduct signals along nerve cells.
Transports material into cells against the concentration gradient (active transport)
Coupled channels (example: Sodium wants to get back into the cell. The cells says "Okay, but you have to bring a sugar with you.")

Transport Proteins

Transport proteins in the plasma membrane transfer solutes such as small ions (Na+, K+, Cl-, H+), amino acids, and monosaccharides.
The proteins involved with active transport are also known as ion pumps.
The protein binds to a molecule of the substance to be transported on one side of the membrane, then it uses the released energy (ATP) to change its shape, and releases it on the other side.
The protein pumps are specific, there is a different pump for each molecule to be transported.
Protein pumps are catalysts in the splitting of ATP → ADP + phosphate, so they are called ATPase enzymes.
- The sodium-potassium pump (also called the Na+/K+-ATPase enzyme) actively moves sodium out of the cell and potassium into the cell. These pumps are found in the membrane of virtually every cell, and are essential in transmission of nerve impulses and in muscular contractions.

Carrier-Mediated Transport--analogy: an elephant carrying people and supplies

A carrier--with characteristics of specificity and saturation is required for this transport, which occurs from the blood into cells such as muscle, liver, and fat cells. This is passive transport because the net movement is to the region of lower concentrations and ATP is not required.
Active transport is similar. Within the cell we have low calcium ions and on the outside we have a high concentration of calcium ions. Because we are going against the concentration. ie: going up hill you have to use energy. If you are going through a gate you can go through without using energy.

The Membrane Potential
Cell Signaling

Ch 6 Questions

1. The rate of diffusion is dependent on which factors?
a. temperature of the solution
b. the permeability of the plasma membrane to the
diffusing substance
c. concentration differences across the two sides of the membrane
d. a and b
e. all of the above

2. What statement for osmosis is NOT true?
a. the simple diffusion of solvent (water) through a membrane
more permeable to the solvent than to the solute
b. osmosis depends on a difference in total solute concentration
c. osmosis depends on the chemical nature of the solute
d. none of the above

3. In passive transport what type of energy is required?
a. No energy required, passive transport is the net movement of molecules and ions across a membrane from higher to lower concentration.
b. ATP
c. Osmosis
d. both b and c.

4. What fibers have been likened to reinforcing iron bars in concrete?
a. Collagen
b. Integrins
c. Elastins
d. Collagens and Elastins

5. A membrane which allows some molecules to pass into or out of a cell is?
a. Carrier Mediated Transport
b. Selectively Permeable Transport
c. Passive Transport
d. Facilitated Diffusion
e. None of the Above

6. Why are the Sodium-Potassium Pumps in cells so important?
a. The extra sodium Na+ is used for "coupled transport" of other molecules.
b. Sodium and Potassium are 2 of the electrolytes in the body and are essential for the nerves, and muscles.
c. The active pumping of the sodium out of the cell prevents cell damage or from causing the cell to burst.
d. All the above
e. none of the above

7. What would be an example of a semipermeable membrane
a. a plastic bag
b pantyhose
c.glass
d a plastic bucket
e. b & c

8. In what kind of solution will a RBC swell and possibly burst?
a. hypertonic solution
b. hypo-osmotic
c. isotonic solution
d. hypotonic solution

9. The chemical driving force for a substance crossing a cell membrane,
a. depends only on the concentration gradient, regardless of whether or not the substance is an ion.
b. depends only on the concentration gradient if the substance is uncharged, but also depends on the electrical force if the substance is an ion.
c. is the total driving force on the substance, even if it is an ion.
d. is the force that pushes molecules across the membrane, but only if the substance is actively transported.
e. always favors movement of a molecule into the cell.

10. The osmotic pressure of a solution depends on
a. the concentrations of all solute particles contained in it.
b. the concentrations of all permeant solute particles contained in it.
c. the concentrations of all impermeant solute particles contained in it.
d. pressure exerted on the solution by the atmosphere.

11. What do pumps and carriers have in common?
a. They both transport molecules up electrochemical gradients.
b. They both transport molecules down the electrochemical gradients.
c. They both transport lipid-soluble substances preferentially.
d. They both utilize ATP to transport molecules
e. They both are specific to certain molecules.

12. The movement of water across a plasma membrane occurs by: a. an active transport water pump.
b. a facilitated diffusion carrier
c. simple diffusion through membrane channels.
d. all of these.

Unit 2 Chapters

flattail — Tue, 06 Jan 2009 14:48:17 CST

There is no abstract available for this page revision.

Enzymes and Energy

flattail — Tue, 06 Jan 2009 14:45:32 CST

Chapter Objectives

1. state the principles of catalysis and explain how enzymes function as catalysts.
2. explain how the names of enzymes are derived and comment on the significance of isoenzymes.
3. describe the effects of pH and temperature on the rate of enzyme-catalyzed reactions and explain how these effects are produced.
4. describe the roles of cofactors and coenzymes in enzymatic reactions.
5. explain how the law of mass action helps to account for the direction of reversible reactions.
6. explain how enzymes work together to produce a metabolic pathway and how this pathway may be affected by end-product inhibition and inborn errors of metabolism.
7. explain how the first and second laws of thermodynamics can be used to predict if metabolic reactions will be endergonic or exergonic.
8. describe how ATP is produced and explain its significance as the universal energy carrier.
9. define the terms oxidation, reduction, oxidizing agent, and reducing agent.
10. describe the use of NAD and FAD in oxidation-reduction reactions and explain the functional significance of these two molecules.

Enzymes as Catalysts

Enzymes are the biological catalysts that increase the rate of chemical reactions. Most enzymes are proteins, the vast differences in protein structures allow each different enzyme to be specialized in their action.

What is life? What is death? What is illness? What is health? What is youth? What is aging?
How do these questions apply to physiology?

We all could come up with some kind of an answer but, It all comes back to the cellular level. What is taking place in the cells?

Checklist of Enzyme Characteristics

-Enzymes are composed of protein and may require co-factor (metallic ion) or coenzyme (organic molecule, such as a vitamin).
-Enzymes act as organic catalysts to speed up the rate of cellular reactions.
-Enzymes lower the activation energy required for a chemical reaction to proceed.
-Enzymes have unique characteristics such as shape, specificity, and function.
-Enzymes enable metabolic reactions to proceed at a speed compatible with life.
-Enzymes provide a reactive site for target molecules called substrates.
-Enzymes are much larger in size than their substrates.
-Enzymes associate closely with substrates but do not become integrated into the reaction products.
-Enzymes are not used up or permanently changed by the reaction.
-Enzymes can be recycled, thus function in extremely low concentrations.
-Enzymes are limited by particular conditions of temperature and pH.
-Enzymes can be regulated by negative feedback and genetic mechanisms.

What is a Catalyst?

We use catalysts often in our daily lives to aid us with whatever it is we may be doing.

-A Catalyst is something that speeds up a reaction.
-It is NOT used up or destroyed during the reaction, so it can be reused again and again!
-It doesn't change the end result of the reaction, it only speeds it up!
-Functionally enzymes are biological catalysts!

-The same reaction would have occurred to the same degree in the absence of the catalyst, but it would have progressed at a much slower rate. In order for a given reaction to occur, the reactants must have sufficient energy. The amount of energy required for a reaction to proceed is called activation energy.

Some examples of active catalysts are:

A Wrench: As our wonderful teacher Kevin said, you could try to turn a bolt with your fingers, but it would be very difficult. If you use a wrench, you will be able to get that bolt off, much faster, and you would have to exert a lot less of your own energy!

Cars: You could walk to Provo from Salt Lake, it would take hours, maybe days, so you wouldn't do it. You would most likely take a car. You conserve your energy and get to Provo much faster! Your "wonderful teacher Kevin" used a bicycle as an example, and not a car. This was a conscious choice--why might I have thought the bicycle would be a better analogy for a catalyst than a car? (see if you can come up with a reason--I'll post my thoughts at the very bottom of this page)

The Laws of Thermodynamics: A set of universal laws governing all energy changes in the universe
1st Law-Energy cannot be created or destroyed, however it changes forms.

Mechanical, sound, light, electric, heat, chemical, etc...

All forms of energy can be converted to Heat. (When you convert one form of energy to another form you lose some of the energy to Heat energy)

2nd Law-Disorder is continuously increasing.

Entropy is a measure of the disorder of the system.

*It doesn't take energy to go to a state of disorder.

Simply put, the 2nd Law states: Entropy increases. If entropy happens spontaneously how do your cells maintain their level of order and complexity?
Answer:It takes energy!

Complexity requires energy.

Energy of Activation

- The energy required for a reaction to proceed.
- Catalysts lower the activation energy of a reaction and thus increases its rate.
- An enzyme can make a reaction happen about a million times faster! Like a switch!
- Enzymes cannot make an endergonic reaction exergonic.

Energy is defined as the ability to do work.

Here is an example of "Activation Energy":
In this video the match has its own stored energy known as potential energy. The activation energy here would be the laser pointer. We typically light matches with friction or another flame, but this is pretty cool! Check it out!

Types of energy:
Potential Energy: Stored Energy

It takes energy to release it.

Kinetic Energy: Energy in Motion

Activation Energy: The amount of action required for a reaction to proceed. Match analogy: Each match has potential energy, but will not release it until some activation energy has been supplied (either by friction or by heat of an already lit match)

Control of Enzyme Activity

Enzymes have the ability to lower the activation energy of a reaction as a result of their structure. They are large structures with 3-Dimensional shapes. Enzymes are proteins that serve as catalysts and help speed up reactions in cells.

What is a substrate?
A substrate is the reactant molecule within an enzyme. Each substrate has a specific shape that allows it to fit into the active site of the enzyme.

How enzymes work:
Enzymes are proteins that serve as catalysts
They speed up chemical reactions within cells
Enzymes bind a specific molecule and stress bonds to make a particular reaction more likely.

Active site
Sites on enzymes surface wherein reactant fits.

Binding site on reactant (substrate) where enzymes binds.

Enzyme shape determines it's activity/changes binding of the substrate.

Factors affecting enzyme activity
Enzyme activity is affected by any change in condition that alters the enzymes 3-D shape. The structural bonds of enzymes are sensitive to changes in temperature and pH.

How Cells Regulate Enzymes

A cell can control the activity of an enzyme by altering it's shape. Allosteric enzymes have shapes that can be altered, but the binding signal molecules.These molecules bind to the alloster site. Repressors bind and repress enzyme activity. Activators bind and restore or increase enzyme activity.

Enzyme inhibition occurs in two ways:
Competitive inhibition-Inhibitor binds at the enzyme's activity site
Non-competitive inhibition-inhibitor binds at the enzyme's alloster site

Constitutive enzymes- always present always produced in equal amounts or at equal rates regardless of amount of substrate, enzymes involved in glucose metabolism.

2 Types of Metabolism
Anabolism-biosynthesis building complex molecules from simple ones requires energy (in the form of ATP)

Anabolic=endergonic

Catabolic-degradation

Breaking down complex molecules into simpler ones, often used to generate ATP
Catabolic=exergonic

Synthesis or Condensation Reactions
Anabolic reactions to form covalent bonds between smaller substrate molecules. Requires ATP and releases one molecule of water for each bond. Removes -H from one side and -OH from the other to form H20 (a water molecule).

Hydrolysis Reaction
Catabolic reactions that break down substrates into small molecules, requires the input of water. Adds water to the molecule and splits it into two smaller molecules.

Metabolic Pathways can be linear, branched (divergent or convergent), or cyclic. Many enzymes are present, each one makes a product that becomes a reactant, that is the reactant for the next protein, A to B to C to D etc.

Bioenergetics

Living organisms require the constant expenditure of energy to maintain their complex structures and processes. Central to life processes are chemical reactions that are coupled, so that the energy released by one reactions incorporated into the products of another reaction. The transformation of energy in living systems is largely based on reactions that produce and destroy molecules of ATP and oxidation-reduction reactions.

Bioenergtics refers to the flow of energy in living systems. Organisms maintain their highly ordered structure and life-sustaining activities through the constant expenditure of energy obtained from their environment.The energy flow in living systems obeys the first and second laws of the physics, which is thermodynamics.

Redox Reaction
This is a simultaneous oxidation-reduction process whereby cellular metabolism occurs, such as the oxidation of sugar in the human body, through a series of very complex electron transfer processes.
The chemical way to look at redox processes is that the substance being oxidized transfers electrons to the substance being reduced. Thus, in the reaction, the substance being oxidized (aka. the reducing agent) loses electrons, while the substance being reduced (aka. the oxidizing agent) gains electrons. Remember: LEO (Losing Electrons is Oxidation) the lion says GER (Gaining Electrons is Reduction).
The term redox state is often used to describe the balance of NAD+/NADH and NADP+/NADPH in a biological system such as a cell or organ. The redox state is reflected in the balance of several sets of metabolites (e.g., lactate and pyruvate, beta-hydroxybutyrate and acetoacetate) whose interconversion is dependent on these ratios. An abnormal redox state can develop in a variety of deleterious situations, such as hypoxia, shock, and sepsis.

Review Questions

1. The amount of energy required for a reaction to proceed is called?
a. enzymes
b. catalysts
c. activation energy
d. cofactors

2. Thermodynamics obeys by which laws?
a. first and third branch
b. first and second branch
c. second and third branch
d. none of the above

3. Which of the following forms does energy exist in?
a. Mechanical, sound, light, electric, heat, chemical
b. Sound, mass, volume, Temperature
c. Light, mechanical, physical, heat, electric
d. Weight, volume, mass

4. Which Statement does not belong in the first Law of Thermodynamics?
a. Energy can change form.
b. During each conversion some energy is lost.
c. Energy is in an ongoing organized motion.
d. Are ya crazy, all of these statements are correct.

5. Which kind of energy uses stored energy?
a. Kinetic Energy
b. Potential Energy
c. Activation Energy
d. Endergonic Energy

6. What is a Catalysts?
a. Enzyme that speeds up a reaction.
b. Protein that speeds up a reaction.
c. Enzyme that slows a reaction.
d. Protein that slows a reaction.

7. What kind of energy can be converted to Heat energy?
a. Mechanical
b. Sound
c. Light
d. Chemical
e. All of the above

8. How do cells regulate enzymes?
a. By killing it
b. By changing its shape
c. By producing different proteins
d. By oxidation

9. What are most enzymes?
a. carbohydrates
b. proteins
c. products
d. none of these.

10. Which of these are the laws of thermodynamics?
a. energy can be transformed.
b. energy can be created and destroyed.
c. the amount of entropy increases in every energy transformation.
d. a and c
e. none of these.

11. What are the 2 types of metabolism?
a. anabolism
b. canabalism
c. catabolism
d. animalism

12. What kind of energy do cells use?
a. chemical
b. heat
c. sound
d. physical

Answer to why I used a bicycle as an example of a catalyst instead of a car: Both bikes and cars speed up the travel, but I didn't use a car because the car itself does work (expends energy), while the bicycle just makes the person's work easier. An enzyme does not do the work itself, but just makes the job easier. No analogy is perfect, but that is why I thought the bike was a closer analogy to an enzyme than a car. ~K

Unit 1 Chapters

flattail — Tue, 06 Jan 2009 14:44:27 CST

There is no abstract available for this page revision.

Cell Structure and Genetic Control

flattail — Tue, 06 Jan 2009 14:43:12 CST

Units Within the Metric System

The metric system is the most widely used system of measurement in the world. It is a more universal measurement standard as compared to the customary system used in the United States.
The three basic units of the metric system are the meter, gram, and liter:

The gram measures weight.The meter measures length.The liter measures capacity.

thousands	hundreds	tens	basic unit	tenths	hundredths	thousandths
1000	100	10	1	0.1	0.01	0.001
kilo-	hecto-	deca-	Meter Gram Liter	deci-	centi-	milli-

A millimeter is about how thick a dime is.
A centimeter is how wide one of your fingernails is.
A kilometer is a little more than half of a mile.

From smallest to greatest they range:

Milli-

Centi-

Deci-

Meter Gram
Liter

Deca-

Hecto-

Kilo-

Conversion Chart for Measuring Length
1 kilometer (km) = 1000 meters (m)
1 meter = 100 centimeters (cm) = 1000 millimeters (mm)1 millimeter = 1000 micrometers (um) Cells are measured in micrometers
1 micrometer = 1000 nanometers (nm) Ribosomes and molecules are measured in nanometers

This system is based on the decimal system and base units of 10s. There are two ways to convert measurements:
All the measurements can either be multiplied or divided by 10, 100, 1,000, and so on. You can follow these short 3 steps if you are not sure what to do.
1. Count the number of zeros in the number you are multiplying or dividing by.
2. If you are multiplying, move the decimal point this number of places to the right.
3. If you are dividing, move the decimal point this number of place to the left.

Drill and Practice

Write the equivalents.

1) 18 m =___ cm
2) 167 mm =_mm
3) 500 kg = _g
4) 23 dm =_hm
5) 1,589 dl =_dm
6) 700 ml =_kl
7) 5 cm = ___mm

ATour of the Cell

The picture above is the basic structure of a cell. The nucleus of the cell is the control center. It is also were the DNA is housed in 23 pairs of chromosomes. This DNA contains all the information for the synthesis of the entire organism.Within these chromosomes there are about 25,000 genes, which code for more than 100,000 proteins. The DNA can't leave the nucleus so, in a process called transcription, segments of DNA are copied as mRNA( messenger RNA), which leaves the nucleus through nuclear pores.
After the mRNA leaves the nucleus,ribosomes attach to it and translate the sequence of nucleic acids into a sequence of amino acids (a polypeptide, orprotein). Ribosomes are about 20 nm in size and are made up of 65% ribosomal RNA (which was made in the nucleolous, a dark region of the nucleus) and 35% ribosomal protein. A ribosome has two sub units a large sub unit and a small sub unit (both units are shown in the figure below).
These subunits come together at the start codon (AUG) of mRNA. Ribosomes may be free-floating, or may be embedded in the rough endoplasmic reticulum. The endoplasmic reticulum (ER) is a network of tubular canals within the cytoplasm. Proteins are produced by ribosomes on the surface of the rough ER and released into the lumen (interior space) of the rough ER. These proteins are then transported to an ER which lacks surface ribosomes (smooth ER). A small vesicle then pinches off from the smooth ER (with proteins inside) and moves through the cytoplasm to the Golgi apparatus for further processing.
The Golgi looks like a “stack of pancakes” and contains enzymes that modify proteins ("post-translational modifications") and prepares them for transport to their final destination, either inside or outside the cell. The Golgi receives proteins and enzymes from the endoplasmic reticulum and packages them into membrane-bound vesicles. Often these vesicles move to the cell membrane and release their contents to the outside of the cell (exocytosis).
The Golgi also prepares lysosomes, which are "bags" of enzymes.The lysosomes assist in the digestion of ingested cellular materials and in the breakdown of worn-out cell organelles. Certain human white blood cells (WBC’s) have numerous lysosomes so they can efficiently destroy ingested bacteria that they have engulfed (through phagocytosis). Cells also have a cytoskeleton, which is made from filamentous proteins called “actin filaments” and “microtubules.”These filaments and tubules assist in the movement of organelles within the cells, the movement of the cell itself, and act to maintain the cell’s shape. Some cells have cilia, which are used to move materials past the cell. A good example is the cells lining the respiratory tract, which have cilia to beat mucus and dust up and out the trachea. Only one human cell type, sperm, has a flagellum, which is a long whip-like structure used for propulsion of cells.

Mitochondria (Power House)
The mitochondria are organelles that make energy for the cell in the form of ATP. All cells need a continuous supply of ATP, and it is in the mitochondria that this molecule is produced. The energy to make ATP comes from the food we eat, so ultimately this is why we eat. Oxygen is the final electron acceptor in the electron transport chain, which is happening in the inner membrane of the mitochondria, so ultimately this is why we breathe.

The mitochondria is sometimes referred to as the cellular power plant. It has it's own DNA and regenerates on it's own, much like the cell that it's found in. A cell CAN NOT make mitochondria.

CBS News published this interesting article on the role of mitochondrial DNA in aging. By inducing a high rate of mutation in mitochondrial DNA, researchers made mice age prematurely, suggesting that degradation of mitochondrial DNA may be one of the causes of aging (not just a result of aging). [Note: Kevin removed the article and replaced it with the link and this summary paragraph to avoid copyright violations]

Here is a simple way to remember the "power" of Mitochondria ...with some killer background music!!! http://www.youtube.com/watch?v=ceDopmx1Y2g

Structure of a cell membrane
A barrier must be present to prevent the loss of enzymes, nucleotides, and other cellular molecules that are water-soluble. This is because both inside and outside the cell contains water. So the cell membrane is composed of lipids. It is considered semipermeable because it is permeable to water, gas molecules, and lipid-soluble molecules, but impermeable to most other molecules.

Phospholipids

Phospholipids create most of the cell membrane. A phospholipid is both hydrophilic (the polar part which contains the phosphate group) and hydrophobic (the nonpolar part that contains the lipid (fat) group). The hydrophobic parts are attracted to each other so they form together making this a double layer of phospholipid. Hence, the lipid tails are pointing in towards each other while the phosphate heads are pointing out. The membrane is not solid--it has an oily consistency, and embedded proteins float in it like icebergs in the ocean. The plasma membrane is sometimes called the fluid mosaic model--fluid because it is not solid and things can move about in it, and mosaic because it is composed of many small pieces. The way of passage into or out of the cell mainly is due to the transport proteins embedded into the cell membrane.
***If something can dissolve in fat (lipid soluble) it can dissolve through the cell membrane. An example is steroid hormones, which are derived from cholesterol (a fat). Lipid insoluble products need to go through a channel protein to pass through the membrane.

Proteins in the cell membrane

The proteins can move around the cell membrane freely and transport materials in and out of the cell. Not all proteins are transport proteins--many are enzymes, and many are cell receptors. The proteins are not uniformally placed throughout the membrane--rather the distribution is patchy, localized depending on their function. Remember that receptor proteins only respond to certain chemicals. This is important because proteins serve as receptors for neurotransmitter chemicals released by nerve fibers at the synapse, for hormones, and for chemical messengers sent from one cell to another.

Carbohydrates

The carbohydrates of the plasma membrane are mainly attached to the outer surface as glycoproteins and glycolipids. The glycolipids of red blood cells serve to determine the blood type. A major group of identification proteins is made by the expression of the MHC (major histocompatability) gene complex. When they are searching for a "matching donor" for an organ or tissue transplant, they are looking for people who have similar MHC genes (hence, similar cell-surface markers).We are lucky that our red blood cells do not express MHC genes or blood donations would be as complex as donating a kidney. The carbohydrates affect interactions between cells and help keep red blood cells apart.

Cholesterol

Cholesterol mainly just stabilizes the cell membrane and is embedded inside the phospholipid.

Genetic Control
For those of you who may be really blown away by our discussion on genetics, here is a great tutorial from the U of U. It includes a tour of the cell, the basic concepts behind genetics, and how to transcribe and translate a gene.

Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. So to say, it is the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately leads to the translation of the genetic code (via the mRNA intermediate) into a functional peptide or protein. The stretch of DNA that is transcribed into an RNA molecule is called a transcription unit. Transcription has some proofreading mechanisms, but they are fewer and less effective than the controls for copying DNA; therefore, transcription has a lower copying fidelity than DNA replication.[1] As in DNA replication, transcription proceeds in the 5' → 3' direction (i.e. the old polymer is read in the 3' → 5' direction and the new, complementary fragments are generated in the 5' → 3' direction). In the case of transcription, the "old polymer" is the DNA template (non-coding) strand. RNA polymerase binds to the 3' end of a gene on the DNA template strand and travels toward the 5' end. In the process, the RNA polymerase synthesizes an RNA molecule from its 5' end to the 3' end. Except for the fact that thymines in DNA are converted to uracils in RNA, the newly synthesized RNA strand will have the same sequence as the coding (non-template) strand of the DNA. For this reason, scientists usually refer to the DNA coding strand when referring to the directionality of genes on DNA, not the template strand. Thus, genes are said to be transcribed in the 5' → 3' direction.

Here is a graphical representation of Transcription
http://www.johnkyrk.com/DNAtranscription.html

Translation is the second process of protein biosynthesis (part of the overall process of gene expression). Translation occurs in the cytoplasm where the ribosomes are located. Ribosomes are made of a small and large subunit which surrounds the mRNA. In translation, messenger RNA (mRNA) is decoded to produce a specific polypeptide according to the rules specified by the genetic code. This is the process that converts an mRNA sequence into a chain of amino acids that form a protein. Translation is necessarily preceded by transcription. Translation proceeds in four phases: activation, initiation, elongation and termination (all describing the growth of the amino acid chain, or polypeptide that is the product of translation). In activation, the correct amino acid (AA) is joined to the correct transfer RNA (tRNA). While this is not technically a step in translation, it is required for translation to proceed. The AA is joined by its carboxyl group to the 3' OH of the tRNA by an ester bond. When the tRNA has an amino acid linked to it, it is termed "charged". Initiation involves the small subunit of the ribosome binding to 5' end of mRNA with the help of initiation factors (IF), other proteins that assist the process. Elongation occurs when the next aminoacyl-tRNA (charged tRNA) in line binds to the ribosome along with GTP and an elongation factor. Termination of the polypeptide happens when the A site of the ribosome faces a stop codon (UAA, UAG, or UGA). When this happens, no tRNA can recognize it, but releasing factor can recognize nonsense codons and causes the release of the polypeptide chain. The capacity of disabling or inhibiting translation in protein biosynthesis is used by antibiotics such as: anisomycin, cycloheximide, chloramphenicol, tetracycline, streptomycin, erythromycin, puromycin etc.

Review Questions

1. The ___________ is also known as the "cellular power plant".
a. ribosome
b. mitochondria
c. golgi complex
d. nucleus
e. endoplasmic reticulum

2. Neurotransmitters are released from the ends of nerve cells are an example of what process?

a. phagocytosis
b. pinocytosis
c. endocytosis
d. exocytosis

3. Cassy the red blood cell went to a physiwiki party and after chatting with the other cells at the party she realized she was out of place and extremely different. Cassy realized the other cells were all under control and that she was lacking a nucleus. This means that Cassy is what?
a. a eukaryote
b. a ribosome
c. a prokaryote
d. a wileEcoyote
[Please see Kevin's comment on this question on the page with answers]

4. After floating around the cell for days the floating solid material was snatched up by the cell and taken inside. This is a process called?
a. excoytosis
b. pinocytosis
c. phagocytosis
d. absorption

5. The cells proteins and lipids are planning to leave the cell. In order for a safe trip outside the cell they must be packaged properly, where do they need to go inside the cell to accomplish this?
a. golgi apparatus
b. vacuoles
c. mitochondria
d. endoplasmic reticulum

6. How many different types of RNA are there?
a. 5
b. 6
c. 3
d. 2
e. 4

7. The term genome can refer to:
a. all the genes in a particular individual
b. only one gene in an individual
c. all the genes in a particular species
d. both a and c
e. none of the above

8. Which of the following is not a function of protein in the cell membrane?
a. structural support
b. synthesis of DNA
c. enzymatic control of chemical reactions
d. receptors for hormones and other arriving regulatory molecules

9. Which of the following organic molecules is not commonly found in the cell membrane?
a. carbohydrates
b. protein
c. cholesterol
d. nucleic acids

10. Which of the following molecules cannot pass through nuclear pores?
a. water
b. potassium ions
c. glycerol
d. DNA

Unit 5 Chapters

flattail — Tue, 06 Jan 2009 14:37:37 CST

Chapter 17-Physiology of the Kidneys

Chapter 18-The Digestive System

Chapter 19-Regulation of Metabolism

Chapter 20 - Reproduction

Unit 4 Chapters

flattail — Tue, 06 Jan 2009 14:37:00 CST

Chapter 13-Blood, Heart, and Circulation

Chapter 14-Cardiac Output, Blood Flow, and Blood Pressure

Chapter 15-The Immune System

Chapter 16-Respiratory Physiology

Unit 3 Chapters

flattail — Tue, 06 Jan 2009 14:28:39 CST

Chapter 10-Sensory Physiology
Chapter 11-Endocrine Glands: Secretion and Action of Hormones
Chapter 12-Muscle: Mechanisms of Contraction and Neural ControlPractice Test

Study Tips

flattail — Tue, 06 Jan 2009 14:17:57 CST

Please feel free to submit any ideas that you find helpful for succeeding in anatomy.

Here is a slideshow about succeeding in chemistry--the same principles apply to succeeding in physiology!

Here are some online seminars that USU has put together to help you achieve success in the classroom:

The Power of Positive Thinking
The Power of Positive Thinking part 2
The Academic Resource Center has many resources to help you be a better student.
There are a lot of websites full of study tips and test-taking strategies. Some of the most popular include studytips.org, how-to-study.com, and study guides and strategies. You can even print out a variety of Idea Sheets VARK assessment to see what type of learning style works best for you.

Great Advice From Fellow Students (feel free to add to this list)

I was very nervous about the test but glad it went okay. I am not sure what I did differently than other students to help prepare for it. I did have a study group a couple times a week (we met for one hour twice a week). I think that it helped to talk about the concepts together. Especially the concepts that we had each had OH! moments to in our own personal study time. We each had come to understand separate individual concepts and it was very helpful to bring the best parts of each of our understandings together. Also, noticing how things tied together amplified our understanding as well. I did study the notes thoroughly... and my family has not eaten for the last week either...
Know well what it is you are reading
- When you look at a question and can't understand it or deduct from it a reasonable answer, then you're not quite understanding the material
- I admit I didn't understand the questions because I didn't understand the content fully. I knew only part of the content so of course I should have only got what I did on the test.
- You can't go and memorize the questions; how good is it to just memorize it if you can't recall what the question actually meant? I try to understand it in my own terms, asking questions to myself and to others
- I might not ask a lot in school, but do ask a lot with the people I work with--I love to gain their knowledge and experience.
- I also like to do the end of the chapter tests so I can see what I have learned from lecture and what I read so I can see what I have retained and what I need to continue to try and understand and what questions I need to ask.
- I also like to study in a comfortable place--nothing too cozy nothing too uncomfortable, but I find sitting in my truck by the river with my own thoughts are good.
- I am not the smartest nor am I simpleton but I strive for success and knowledge is the key and asking questions is the answer! Speak up even if you are not sure whether you are right or wrong; you'll be surprised how two minds are better then one, and don't presume to know all the answers because you will learn something new each day.
- Oh and remember to breathe and relax, tension causes the mind to suddenly have a memory block and you begin to panic and that's when things go wrong and errors happen the most.

6. A few things I found very helpful (from a student): 1) memorizing the Latin roots at the back of the book, 2) making my own flash cards. The act of writing all the info down and being able to take it wherever I went helped a bunch, 3) taking all the practice quizzes on the books web-site. You have to know the material to be able to answer those questions from the difficult Multiple choice, 4) Listening to certain lectures over again, 5) Lots of study time.
7. (suggestion copied from an anatomy/physiology discussion board): One of the most important things for you to do is develop good study habits & skills.There are many strategies available.They aren't all applicable to every individual. You will have to experiment to find which methods work best for you.I suggest that you begin by designating a quiet, comfortable place as your "study space". Eliminate ALL distractions. Turn the phones, TV, radio, etc. OFF. Have EVERYTHING that you need to study within arms reach, including text, lab manual, notes, handouts, flashcards, pens/pencils, paper, snack.....The ONLY reason that you should have to get up is to go to the bathroom. Invest in one of those "port-o-potties" at the local RV dealership and you won't even have to do that. READ your textbook, section by section, and take notes on them as you progress. As you begin, make a list of the key terms and define them. Keep that list handy as you read. It is difficult to understand concepts if you do not understand the terminology and the definitions. You have to disrupt the flow of information in order to look up words and meanings. After you have read and taken notes, go back and read the entire chapter from beginning to end. This will help you"connect the dots" and see how the concepts relate to one another.
8. I like to go to http://www.youtube.com/ and do a simple search for a section of the body, a body part, a muscle, a nerve, or body system, such as the circulatory system for example. I have been able to find every video I have searched for. I love watching the videos because I`m able to see a good dissection of what I`m searching for or a diagram. I like hearing the narration to the videos, so I can learn visually and hear it as well.

Some advice from other instructors, TAs, etc:

If your philosophy is I want an A, then you will at least need to do the following: Know 100% of the material. Be able to think about the material and understand how ideas, terms, and concepts inter-relate. If you feel that you could teach these ideas to others you are probably on the right track. You must look at this goal as a challenge that is obtainable but requires effort. You will probably have to work harder than you have in other courses. These students have read ahead in the lecture notes and come to class with questions instead of no understanding of the topic. They employ good study and test taking strategies.
If you do not understand the vocabulary, you will fall into a pit of deepening confusion. Just memorizing the material will not be enough to succeed on tests—you must understand and be able to use the language. Maintain a list of unfamiliar words—perhaps in a notebook, or on flash cards. Skim the notes before class and highlight all unfamiliar words. Then pay attention to those words in class. If you don’t understand a word or concept after it is defined, immediately ask a question to clarify. Another great tool for vocabularly is to do a “define:” search on Google. For example, typing define: mitochondria would return short definitions of mitochondria from across the web, as seen here, rather than a list of websites. Don’t forget to type “define:” (with a colon) before the word of interest.
Use Wikipedia and other sources rather than just studying from a single source.

Chapter 14

flattail — Tue, 09 Dec 2008 17:25:44 CST

Cardiac Output, Blood Flow, and Blood Pressure

In addition to the materials listed here you may be interested in Tufts University's free open courseware about cardiac physiology and pathophysiology

The heart in Technicolor loveliness!!

An efficient circulatory system has:
1. blood to carry materials to be transported;
2. A system of vessels to distribute the blood;
3. A pump (heart) to push the blood through the system;
4. exchange organs to carry out exchanges between the blood and the external envionrnment.
-lungs and intestines to add material to the blood
-lungs, skin, and kidneys to remove materials from the blood.

CARDIAC OUTPUT
The pumping ability of the heart is a function of the beats per minute (cardiac rate) and the volume of blood ejected per beat (stroke volume). The cardiac rate and stroke volume are regulated by the autonomic nerves and by mechanisms intrinsic to the cardiovascular system.

1. Cardiac output-is the volume of blood pumped per minute by each ventricle.
2. Cardiac rate-the average resting rate in an adult is 70 beats per minute.
3. Average stroke volume-volume of blood pumped per beat by each ventricle.

Cardiac output can be found by multiplying the stroke volume by the cardiac rate.
This can be affected by exercise, as the heart rate increases so does the output.

Total blood volume also averages about 5.5L. The heart pumps the equivalent of this in a minute at resting heart rate.

Way cool picture of beating heart!!!

Tachycardia is a fast heart rate and Bradycardia is slow heart rate.
For example A cardiac rate slower than 60 beats per minute indicates Bradycardia. A rate faster than 100 beats per minute is described as Tachycardia.
Both of these can occur normally. Endurance trained athletes often have heart rates ranging from 40 to 60 beats per min. This is a beneficial adaptation.

"Lub-Dub"
The first heart tone, or S1, "Lub" is caused by the closure of the atrioventricular valves, mitral and tricuspid, at the beginning of ventricular contraction, or systole. When the pressure in the ventricles rises above the pressure in the atria, these valves close to prevent regurgitation of blood from the ventricles into the atria. The second heart tone, or S2 (A2 and P2), "Dub" is caused by the closure of the aortic valve and pulmonic valve at the end of ventricular systole. As the left ventricle empties, its pressure falls below the pressure in the aorta, and the aortic valve closes. Similarly, as the pressure in the right ventricle falls below the pressure in the pulmonary artery, the pulmonic valve closes.

Aortic Valve Stenosis
The aortic valve controls the direction of blood flow from the left ventricle to the aorta. When in good working order, the aortic valve does not impede (block) the flow of blood between these two spaces. Under some circumstances, the aortic valve becomes narrower than normal, impeding the flow of blood. Aortic Stenosis cannot be repaired, the only option is valve replacement.

ARRHYTHMIAS
*An arrhythmia is any abnormal heartbeat (too fast, Too slow, irregular, fibrillation's)
*Can change from benign to life-threatening
*In many cardiac arrhythmia's, the premature or abnormal beats do not produce an effective pumping action and are experienced as “skipping beats”

Bypass Surgery, Coronary Artery

What is coronary artery bypass surgery?
This is a type of heart surgery. It's sometimes called CABG ("cabbage"). The surgery reroutes, or "bypasses," blood around clogged arteries to improve blood flow and oxygen to the heart.
Why is this surgery done?
The arteries that bring blood to the heart muscle (coronary arteries) can become clogged by plaque (a buildup of fat, cholesterol and other substances). This can slow or stop blood flow through the heart's blood vessels, leading to chest pain or a heart attack. Increasing blood flow to the heart muscle can relieve chest pain and reduce the risk of heart attack. (LAD most commonly blocked)
How is coronary bypass done?
Surgeons take a segment of a healthy blood vessel from another part of the body and make a detour around the blocked part of the coronary artery.

An artery may be detached from the chest wall and the open end attached to the coronary artery below the blocked area.

A piece of a long vein in your leg may be taken. One end is sewn onto the large artery leaving your heart—the aorta. The other end of the vein is attached or "grafted" to the coronary artery below the blocked area.

Either way, blood can use this new path to flow freely to the heart muscle.

Blood Type
Agglutination Reaction:
People with type A blood have type A antigens on their red blood cells and antibodies in their plasma against the type B antigen. People with type B blood have type B antigens on their red blood cells and antibodies in their plasma against the type A antigen. Therefore, if red blood cells from one blood type are mixed with antibodies from the plasma of the other blood type, an agglutination reaction occurs. In this reaction, red blood cells stick together because of antigen-antibody binding.
You can make antibodies against One anti-body and they can bind to more than one cell. The agglutination is how you know what type of blood you have .Tested by mixing blood with …

o Anti-A
o Anti-B
o Anti-rH.

Type O is a universal blood donor If you give someone Type B Blood who is a Type A you will cause problems in the kidneys, Because you will cause the the body to make anti-B which will clot and block off the kidneys.

Surface Antigens
Several different RBC surface antigens stemming from one allele (or very closely linked genes) are collectively labeled as a blood group system (or blood group). The two most important blood group systems were discovered during early experiments with blood transfusion, the ABO group in 1901 and the Rhesus group in 1937 . These two blood groups are reflected in the common nomenclature A positive, O negative, etc. with letters referring to the ABO group and positive/negative to the presence/absence of the RhD antigen of the Rhesus group. Development of the Coombs test in 1945 and the advent of transfusion medicine led to discovery of more blood groups.

Blood Group AB individuals have both A and B antigens on the surface of their RBCs, and their blood serum does not contain any antibodies against either A or B antigen. Therefore, a individual with type AB blood can receive blood from any group (with AB being preferable), but can only donate blood to another group AB individual. AB blood is also known as "Universal receiver."

Blood Group A individuals have the A antigen on the surface of their R BCs, and blood serum containing IgM antibodies against the B antigen. Therefore, a group A individual can only receive blood from individuals of groups A or O (with A being preferable), and can donate blood to individuals of groups A or AB.

Blood Group B individuals have the B antigen on their surface of their RBCs, and blood serum containing IgM antibodies against the A antigen. Therefore, a group B individual can only receive blood from individuals of groups B or O (with B being preferable), and can donate blood to individuals of groups B or AB.

Blood group O individuals do not have either A or B antigens on the surface of their RBCs, but their blood serum contains IgM antibodies against both A and B antigens. Therefore, a group O individual can only receive blood from a group O individual, but they can donate blood to individuals of any ABO blood group (ie A, B, O or AB). O blood is also know as "Universal donor."

Rh Factor
Many people have the Rh Factor on the red blood cell. Rh carriers do not have the antibodies for the Rh Factor, but can make them if exposed to Rh. Most commonly Rh is seen when anti-Rh antibodies cross from the mothers placenta into the child before birth. The Rh Factor enters the child destroying the child's red blood cells. This is called Hemolytic Disease.

Hemolytic Disease of the Newborn
Often a pregnant woman carries a fetus with a different blood type to herself, and sometimes the mother forms antibodies against the red blood cells of the fetus, leading to low fetal blood counts, a condition known as hemolytic disease of the newborn.
Hemolytic disease of the newborn, (also known as HDN) is an alloimmune condition that develops in a fetus when the IgG antibodies produced by the mother and passing through the placenta include ones which attack the red blood cells in the fetal circulation. The red cells are broken down and the fetus can develop reticulocytosis and anemia. The fetal disease ranges from mild to very severe and fetal death from heart failure - hydrops fetalis - can occur. When the disease is moderate or severe many erythroblasts are present in the fetal blood and so these forms of the disease can be called erythroblastosis fetalis.

Before birth, options for treatment include intrauterine transfusion or early induction of labor when pulmonary maturity has been attained, fetal distress is present, or 35 to 37 weeks of gestation have passed. The mother may also undergo plasma exchange to reduce the circulating levels of antibody by as much as 75%.

After birth, treatment depends on the severity of the condition, but could include temperature stabilization and monitoring, photo-therapy, transfusion with compatible packed red blood, exchange transfusion with a blood type compatible with both the infant and the mother, sodium bicarbonate for correction of acidosis and/or assisted ventilation.

Rh negative mothers who have had a pregnancy with or are pregnant with a Rh positive infant, are given Rh immune globulin (RhIG) also known as Rhogam, during pregnancy and after delivery to prevent sensitization to the D antigen. It works by binding any fetal red cells with the D antigen before the mother is able to produce an immune response and form anti-D IgG. A drawback to pre-partum administration of RhIG is that it causes a positive antibody screen when the mother is tested which is indistinguishable from immune reasons for antibody production. Also worth noting is that when a woman has a miscarriage and she is Rh negative, she will receive a shot of Rhogam. If they are unsure of her blood type some Doctors and Emergency Centers will give the Rhogam shot as a precaution. Which will not hurt the mother.

Hemolytic disease of a newborn:
-Is when the baby is born with Rh positive and the mother is Rh negative which causes an enlargement of the liver and spleen. (associated with red blood cell destriction) The enlargement is due to the liver and spleen trying to clean all the red blood cells that were destroyed by moms antibodies. Although the antibodies won't stick around forever because the mother was the one producing the antibody not the baby, so the baby won't produce any antibody. So you can gvie the baby a transfusion of Rh negative blood so the baby will have alot of red blood cells that the antibodies are not attacking and after a few moths the antibodies will be out of the system.

Shock as it relates to the cardiovascular system, rapid, uncontrolled fall in blood pressure, which in some cases becomes irreversible and leads to death.

There are 3 basic causes of shock
1. Pump failure
2. Vessel failure
3. Content failure

Some examples are:
Septic shock: refers to a dangerously low blood pressure (hypotension) that may result form sepsis or infection. This can occur through the action of a bacterial lipoplysaccharide called endotoxin. The mortality with septic shock is presently high, 50 % to 70 %. Endotoxin activates the enzyme nitric oxide synthase within macrophages-cells that play an important role in the immune system. Nitric oxide synthase produces nitric oxide, which promotes vasodilation and, as a resule, a fall in blood pressure. Septic shock has recently been treated effectively with drugs that inhibit the productio of nitric oxide. But even with the treatment the mortality rate is still 50 to 70%
Anaphylactic shock: A rapid fall in blood pressure as a result of a severe allergic reaction (usually due to a bee sting or penicillin). This results from the widespread release of histamine, which causing vasodilation and thus decreases total peripheral resistance The rapid fall of blood pressure in anaphylactic shock is due to precapillary sphinctors opening all throughout the body.
Vasovagal syncope (passing out): A really STUPID thing some adolescents do (stupid because it cuts off oxygen to the brain and has risk of permanent brain damage or death) is to make each other pass out. Don't do this. The basic response is a drop in blood pressure, either by choking (as seen in the video) or by hyperventilating and pressing on the heart.

Hemophilia

Hemophilia is the name of a family of hereditary genetic disorders that impair the body's ability to control blood clotting, or coagulation. When a blood vessel is injured, a temporary scab does form, but the missing coagulation factors prevent fibrin formation which is necessary to maintain the blood clot. Thus a hemophiliac does not bleed more than a normal person, but for a much longer amount of time. In severe hemophiliacs even a minor injury could result in a massive hemorrhage lasting days, weeks, or not ever healing completely.

PLASMA MAKE-UP

Plasma is made up of 90% water, 7-8% soluble proteins (albumin maintains bloods osmotic integrity, others clot, etc), 1% electrolytes, and 1% elements in transit. 1% of the plasma is salt, which helps with the pH of the blood. The largest group of solutes in plasma contains three important proteins to be discussed. There are: albumins, globulins, and clotting proteins.
Albumins are the most common group of proteins in plasma and consist of nearly two-thirds of them (60-80%). They are produced in the liver. The main function of albumins is to maintain the osmotic balance between the blood and tissue fluids and is called colloid osmotic pressure. In addition, albumins assist in transport of different materials, such as vitamins and certain molecules and drugs (e.g. bilirubin, fatty acids, and penicillin).
Globulins are a diverse group of proteins, designated into three groups: gamma, alpha, and beta.

Streptococci--the one that causes strep throat is really bad if it gets into your blood stream. You develop antibodies against it. Ends up matching a protein on your heart valves which in turn damages your heart valves. This can happen if you get Strep throat and it is left untreated (rheumatic heart disease) It usually doesn't show up for years after the streptococcal infection. It is seen with Scarlet fever and Rheumatic fever.

One cool side note: They will not do open heart if you have any infections in your mouth. Also, if you have too many current cavities. They will have you wait until 6 months after it has cleared up. Just thought that was neat info.

The Electrocardiogram (ECG)

Also know as the Electrocardiogram. Cardiac electro-physiology is the science of the mechanisms, functions, and performance of the electrical activities of specific regions of the heart. The EKG is the recording of the heart's electrical activity as a graph. The graph can show the heart's rate and rhythm, it can detect enlargement of the heart, decreased blood flow, or the presence of current or past heart attacks. EKG's are inexpensive, Non-invasive, quick, and painless. Depending on the results, the patient’s medical history, and a physical exam; further tests or a combination of medications and lifestyle changes may be ordered.

P wave - indicates that the are electrically stimulated to pump blood into the ventricles.
QRS complex- indicates that the ventricles are electrically stimulated to pump blood out. The ventricles depolarizing and contracting.
ST segment- indicates the amount of time from the end of the contraction of the ventricles to the beginning of the T wave.
T wave- indicates the recovery period of the ventricles.

A little song about Renin-Angiotensin-Aldosterone system

Blood pressure

What is blood pressure?

Blood pressure is the pressure of the blood against the walls of the arteries.
Blood pressure results from two forces. One is created by the heart as it pumps blood into the arteries and through the circulatory system. The other is the force of the arteries as they resist the blood flow.

What do blood pressure numbers indicate?

The higher (systolic) number represents the pressure while the heart contracts to pump blood to the body.

The lower (diastolic) number represents the pressure when the heart relaxes between beats.

The systolic pressure is always stated first. For example: 118/76 (118 over 76); systolic = 118, diastolic = 76.

Blood pressure below 120 over 80 mmHg (millimeters of mercury) is considered optimal for adults. A systolic pressure of 120 to 139 mmHg or a diastolic pressure of 80 to 89 mmHg is considered "prehypertension" and needs to be watched carefully. A blood pressure reading of 140 over 90 or higher is considered elevated (high).

QUESTIONS

1. "Lub" is the sound of which valves shutting?
a. semi-lunar and pulmonary valves
b. tricuspid and bicuspid valves
c. both a and b
d. none of the above

2. Which artery or vein is most commonly used for bypass surgery?
a. brachial artery
b. greater saphenous
c. mammary veins
d. both b and c
e. none of the above

3. Edema may be caused by _________
a. high blood pressure
b. decreased plasma protein
c. leakage of plasma protein into tissue fluid
d. blockage of lymphatic vessels
e. all of the above

4. Each Normal heartbeat is initiated by the:
a. AV node
b. bundle of HIS
c. SA node
d. ventricles

5. The function of the serous fluid of the membranes is to:
a. prevent friction as the heart beats
b. prevent abnormal clotting in the chambers of the heart
c. keep blood flowing through the heart
d. nourish the myocardium

6. The term systole means:
a. rapid heart rate
b. slow heart rate
c. relaxation
d. contraction

7. A normal range of heart rate for a healthy adult is _______________ beats per minute.
a. 90-100
b. 70-100
c. 60-80
d. 50-60

8. The electrical activity of the heart may be depicted in an:
a. EEG
b. Egg
c. ECG
d. ECC

9. The nerves that transmit impulses to decrease the heart rate are the:
a. sympathetic nerve
b. coronary nerve
c. glossopharyngeal nerve
d. vagus nerve

10. The amount of blood pumped by a ventricle in 1 minute is called:
a. stroke volume
b. pulse
c. coronary blood flow
d. cardiac output

11. A heart rate below 60 is called:
a. a murmur
b. bradycardia
c. tachycardia
d. galloping

12. The hormone ANP increases the loss of _____________________ in urine to decrease blood volume and blood pressure.
a. calcium ions
b. sodium ions and water
c. potassium ions
d. water only

13. The first part of the cardiac conduction pathway in the ventricles is the:
a. bundle of HIS
b. AV node
c. bundle branch
d. fiber

14. The difference between resting cardiac output and maximum exercise cardiac output is called the:
a. cardiac override
b. cardiac limit
c. cardiac reserve
d. cardiac extra

15. Blood pressure is lowest in
a. arteries
b. arterioles
c. capillaries
d. veins

16. The pulse pressure is a measure of
a. the number of heartbeats per minute.
b. the sum of the diastolic and systolic pressure
c. the difference between the systolic and diastolic pressures
d. the difference between the arterial and venous pressure

17. When an Rh negative mother gives birth to a Rh positive baby, which of these is not true?
a. the baby will be born with Haemolytic disease
b. the mother will develop antibodies against fetus
c. the mother will need Rhogam shots
d. the baby will need Rhogam shots

18. The soluble protein that precipitates to become fibrin in the presence of thrombin is called_____.
a. thrombopoietin
b. rythropoietin
c. plasma protein
d. hemoglobin

19. What is the most commonly used vein for Bypass heart surgery
a. femoral vein
b. common iliac vein
c. great saphenous vein
d. radial vein

20. What is one of the main things that will happen if a type A person is given type B blood?
a. You will urinate yourself to death
b. Your heart will immediately stop beating
c. You will have 1000's of cells being destroyed all at once by phagocytic cells and complement proteins and those destroyed cells will clog your kidneys
d. It will cause a release of bacteria in the blood that will attack your immune system that will result in the hypotension of septic shock
e. none of the above

Lactic Acid

flattail — Fri, 05 Dec 2008 15:26:39 CST

Many people say that lactic acid causes muscle fatigue. It's not that simple! As this article discusses, the lactate ion is used as a source of fuel in the mitochondria.

Here are some comments from a retired exercise physiologist in response to the NY times article:

There is a difference between muscle soreness and muscle fatigue.

Muscle soreness is what one experiences 24-48 hours after strenuous exercise or physical activity and is usually caused by muscle trauma ("pulled muscle fibers") and/or inflammation (where interstitial fluid accumulates in the injured muscle and spaces) all resulting in the stimulation of pain receptors in the area.

Muscle fatigue has many causes, one is the lack of sufficient metabolic fuels for the muscles (glycogen or glucose). Short-term high intensity exercise (in the "anaerobic zone") does produce lactic acid and leads to the fatigue in untrained (out-of-shape) muscles. The lactic acid will dissociate in the muscle tissue (into free Hydrogen ions [H+] and lactate ions). The lactate ions ARE definitely still a fuel source. They enter pathways to yield further ATP production. But the free H+ ions form an acidic environment around the muscles which DOES lead to a decrease in muscle tension and fatigue.

One hypothesis is the accumulation of free H+ ions around the muscle sarcomeres interferes with the formation of cross-bridges between actin and myosin fibers. It blocks the troponin-tropomyosin action and thus fewer cross-bridges form or are detached and that leads to the inability of the muscle to maintain tension, thus fatiguing. The excess H+ ions are undoubtedly responsible for the "burn" in the anaerobic exercise.

As one improves his/her fitness level through training, a number of adaptations do occur within the muscles. One is enhanced capillarization in the trained muscles (bringing more nutrients and removing metabolic wastes). Another is an increase in the size and number of mitochondria within the working muscles (more and larger mitochondria enable faster, more efficient metabolic pathways). Another adaptation is the production of buffers within the blood and interstitial fluids thus 'neutralizing' the excess H+ ions that may accumulate. Elite athletes thus are able to perform longer and more efficiently because of these adaptations.

The lactate ions are metabolized both in the muscles and the liver (by the mitochondria) as a further source of producing ATP. Actually the cardiac muscle "feeds" most often on lactate ions.

Unit 1 Chapters	Unit 2 Chapters	Unit 3 Chapters
Study of Body Function Cell Structure and Function Enzymes and Energy Practice Questions	Cell Respiration and Metabolism Interactions Between Cells and Their Environment Neurons & Synapses Autonomic Nervous System Practice Questions	Senses Endocrine Glands Muscle Physiology Practice Questions
	Study Tips
Lecture recordings	Online physiology book	Cool Questions

Unit 4 Chapters	Unit 5 Chapters	Other Links of Interest
Blood, Heart, Circulation Cardiac Output, Blood Flow & Pressure The Immune System Respiratory Physiology	Renal Physiology Digestive System Regulation of Metabolism Reproduction	Government health links Microbiowiki Radiographywiki Anatowiki Editing tips www.aris.mhhe.com

Everything Physiology! - Recently Updated Pages

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Cell Respiration and Metabolism

Cellular respiration--the process of making ATP, can be divided into Glycolysis, Kreb's Cycle (also called Citric Acid Cycle), and the Electron Transport Chain

Here are some ways, system by system, that the body is using ATP

INTEGUMENTARY SYSTEM

NERVOUS SYSTEM

ENDOCRINE SYSTEM

MUSCULAR SYSTEM

CIRCULATORY SYSTEM

RESPIRATORY SYSTEM

URINARY SYSTEM

DIGESTIVE SYSTEM

REPRODUCTIVE SYSTEM

Study of Body Function

Chapter Objectives

Scientific Method

Homeostasis and Feedback Control

Positive and Negative Feedback

When a change of variable occurs, there are two main types of feedback to which the system reacts:

Neural and Endocrine Regulation

Nervous System

Endocrine System

Feedback Control of Hormone Secretion

The Primary Tissues

Organs and Systems

Muscular System

Cardiovascular System

Digestive System

Body-Fluid Compartments

Review Questions

Physiwiki World

Online Resources

Nervous System

Chapter Objectives

A brain researcher discovers what it is like to have a stroke

The Nervous System: Neurons and Synapses

Structure of a neuron

Synapse:

The Nerve Impulse

All or none law

Acetylcholine as a neurotransmitter

Chemically regulated Channels

Ligand-Gated Channels

G-Protein-Coupled Channels

Acetylcholinesterase (AChE)

Acetylcholine in the PNS

Neuroscience

QUESTIONS

Chapter 13

Blood, Heart, and Circulation

Formed Elements of Blood, The formed elements of blood include two types of blood cells: erythrocytes, or red blood cells, and leukocytes, or white blood cells.

Gas Exchange

Chapter 11: Endocrine Glands

PITUITARY GLAND

Hormones of the Posterior Pituitary Gland:

Hormones of the Anterior Pituitary Gland:

Diseases of the Thyroid

Pancreas and Other Endocrine Glands

Autonomic Nervous System

The Autonomic Nervous System

Autonomic versus Somatic NS

ANS Neurotransmitters

Reflex Arc

Interactions between Cells & the Extracllular Enviroment

Extracellular Environment

Unit 2 Chapters

Enzymes and Energy

Chapter Objectives

Enzymes as Catalysts

Checklist of Enzyme Characteristics

What is a Catalyst? We use catalysts often in our daily lives to aid us with whatever it is we may be doing.

Energy of Activation

Control of Enzyme Activity

Binding site on reactant (substrate) where enzymes binds.

A cell can control the activity of an enzyme by altering it's shape. Allosteric enzymes have shapes that can be altered, but the binding signal molecules.These molecules bind to the alloster site. Repressors bind and repress enzyme activity. Activators bind and restore or increase enzyme activity.

Anabolic=endergonic

Catabolic-degradation

Bioenergetics

Review Questions

What is a Catalyst?

We use catalysts often in our daily lives to aid us with whatever it is we may be doing.

Units Within the Metric System

The metric system is the most widely used system of measurement in the world. It is a more universal measurement standard as compared to the customary system used in the United States.
The three basic units of the metric system are the meter, gram, and liter:

1) 18 m =___ cm
2) 167 mm =_mm
3) 500 kg = _g
4) 23 dm =_hm
5) 1,589 dl =_dm
6) 700 ml =_kl
7) 5 cm = ___mm