Regulation of Metabolism

If you liked Dean Orish's 3-minute talk, and if you want to get distracted with many amazing talks on a wide breadth of topics, then check out the TED Talks!

Dr. Mercola is indeed a medical doctor, but also definitely considered "fringe" for many of his views. I enjoy his free newsletters that focus on preventive medicine. Here is a long article on his site about insulin and its metabolic effects. ~K

Objective 1
Identify factors that influence the Metabolic rate and explain the significance of the Basal Metabolic rate.

Metabolic Rate
The total rate of body metabolism, or the metabolic rate, can be measured by either the amount of heat generated by the body or by the amount of oxygen consumed by the body per minute. This rate is influenced by a variety of factors. For example, the metabolic rate is increased by physical activity and by eating. Body temperature is also an important factor in determining metabolic rate.
The metabolic rate (measured by the rate of oxygen consumption) of an awake, relaxed person 12 to 14 hours after eating and at a comfortable temperature is known as the basal metabolic rate (BMR). The BMR is determined primarily by a person's age, sex, and body surface area, but it is also strongly influenced by the level of thyroid secretion.

Nutrition

Nutrients
• Nutrition is the taking in and the use of food.
• Nutrients are the chemicals used by the body and consist of carbohydrates, lipids, proteins, vitamins, minerals, and water.
• Essential nutrients cannot be produced by the body or cannot be produced in adequate amounts.

Metabolism

• Metabolism consists of anabolism and catabolism. Anabolism is the synthesis of molecules and requires energy. Catabolism is the breaking down of molecules and gives off energy.
• The energy in carbohydrates, lipids, and proteins is used to produce ATP.

Regulation of Metabolism

• Biochemical pathways are a series of chemical reactions, some of which release energy that can be used to synthesize ATP.
• Each step in a biochemical pathways requires enzymes.
• Enzyme synthesis is determined by DNA. Enzyme activity is modified by receptor-mediated and end product processes.

Carbohydrate Metabolism

• Glycolysis is the breakdown of glucose to two pyruvic acid molecules. Two ATP molecules are also produced.
• Anaerobic respiration is the breakdown of glucose in the absence of oxygen to two lactic acid molecules and two ATP molecules.
• Lactic acid can be converted to glucose using aerobically produced ATP; the necessary oxygen is the oxygen debt.
• Aerobic respiration is the breakdown of glucose in the presence of oxygen to produce carbon dioxide, water, and 38 molecules of ATP.
  • The first phase of aerobic metabolism is glycolysis.
  • The second phase of aerobic metabolism is the conversion of pyruvic acid to acetyl-CoA.
  • The third phase of aerobic metabolism is the citric acid cycle.
  • The fourth phase is the electron-transport chain, which uses carrier molecules such as NADH to synthesis ATP.

Lipid Metabolism

• Lipids are broken down in adipose tissue, and fatty acids are released into the blood.
• Fatty acids are taken up by cells and broken down into acetyl-CoA, which can enter the citric acid cycle. Acetyl-CoA can also be converted into ketones by the liver. Ketones released from the liver into the blood are used as energy sources by other cells.

Protein Metabolism

• Amino acids are used to synthesize proteins.
• Amino acids can be used for energy, and ammonia is produced as a by-product.
  • Ammonia is converted to urea and excreted by the kidneys.

Metabolic States

• In the absorptive state, nutrients are used as energy or stored.
• In the post-absorptive state, stored nutrients are used for energy.

Metabolic Rate

• Metabolic rate is the total energy expenditure per unit of time.
• Although the term metabolism is used to describe all of the chemical reactions that take place within the body, metabolic rate is usually expressed as an amount of heat production. This is because many body processes that utilize ATP also produce heat. These processes include the contraction of skeletal muscle, the pumping of the heart, and the normal breakdown of cellular components. Therefore, it is possible to quantify heat production as a measure of metabolic activity.
• Metabolic energy is used for basal metabolism, muscular activity, and the assimilation of food.
• Your oxygen consumption when relaxed, in a comfortable room temperature, 12 to 14 hours after eating.

Primary factors influencing BMR include:
*sex*age
*body structure
*thyroid secretions

Biggest determinant to your personal metabolic rate is physical activity.



Kilocalories
When caloric intake is greater than caloric expenditure, you gain weight (excess calories stored as fat) and when caloric intake is less than caloric expenditure you lose weight. However, your body will adjust its metabolic rate to maintain your weight around a certain point, so it may take awhile to change your weight. Remember your body resists change!!! Kilocalories

• A kilocalorie is the energy required to raise the temperature of 1000 g of water from 14°C to 15°C. A kilocalorie is the unit of measurement used to express the energy content of food.

A Calorie (big "C") is really a kilocalorie or 1,000 calories. A calorie (little "c") is the energy needed to heat one ml of water one degree Celsius.
Carbohydrates and proteins have 4 Body calories per gram, while fat has 9 calories per gram.

Temperature Regulation

Body temperature is a balance between heat gain and heat loss.

Heat is produced through metabolism.

Heat is exchanged through radiation, conduction, convection, and evaporation.

The greater the temperature difference, the greater the rate of heat exchange.

Body temperature is regulated at a "set point" by neural circuits in the hypothalamus.

Hypothermia
Hypothermia is a low body temperature. This is a dangerous condition that is defended against by shivering and other physiological mechanisms that generate body heat, however it has proved itself useful when it comes to heart attacks and performing surgery on the heart or the brain. There is even a machine that can pump your blood through a machine to cool it off sometimes as low as 70 degrees. This is important since the cells have a low metabolic need during this time.

Objective #2
Distinguish between the caloric and anabolic requirements for food and define the terms Amino Acids and Essential Fatty Acids.

CARBOHYDRATES

• Carbohydrates include , disaccharides, and polysaccharides.
• Most carbohydrates we ingest are from plants.
• Carbohydrates are used as an energy source and for making DNA, RNA, and ATP.
• The recommended amount of carbohydrate is 125 to 175 g daily, although there are no essential carbohydrates (the body can make carbohydrates from fats or proteins).

LIPIDS

• Lipids include triacylglycerol, phospholipids, steroids, and fat-soluble vitamins. Triacylglycerol is a major source of energy. Prostaglandins are involved in inflammation, tissue repair, and smooth muscle contraction. Cholesterol and phospholipids are part of the cell membrane. Some steroid hormones regulate the reproductive system.
• It is recommended that fats account for no more than 30% of the total kilocaloric intake, but Kevin presented a contrarian point of view that you could obtain a majority of your calories from healthy fats (mainly polyunsaturated fats from plants). 90% of the body's energy stores are in the form of fat, not glycogen. Most cells can metabolize lipids as an energy source, and lipids can also be converted to carbohydrates for the cells that rely on glucose metabolism.
• The modern American diet is high in saturated fats (mainly from animals). Trans fats are vegetable oils that have been hydrogenated (saturated with hydrogens at the double bonds). These have received attention lately for their negative effects on health and should be avoided (they are found in many processed foods because they increase shelf life).

Proteins

• Proteins are chains of amino acids. There are 21 amino acids and we need all of them, but only 9 are considered essential because we can make all of the others.
• Animal proteins tend to be complete proteins, whereas plant proteins tend to be incomplete, meaning they are lacking in one or more essential amino acids.

• Proteins are involved in structural strength, muscle contraction, regulation, buffering, clotting, transport, ion channels, receptors, and the immune system.
• The recommended daily consumption of protein is 0.8 g/kg of body weight per day.
• Cells will use proteins as an energy store only as a "last resort" when fat stores have been depleted and carbohydrates are unavailable.

Vitamins

• Vitamins are not a source of energy. Rather they are organic molecules needed in very small amounts for normal body functioning. Some vitamins are coenzymes; that is they are necessary for the functioning of certain enzymes, such as enzymes involved in energy production, nucleic acid synthesis, growth, and blood clotting. Other vitamins are antioxidants, including vitamins C, E and betacarotene. Antioxidants prevent damage from free radicals, which are molecules that contain an unpaired electron and are highly reactive.
• Most vitamins are not produced by the body and must be obtained in the diet. Some vitamins can be formed from pro-vitamins (precursor molecules).
• 
  
• Vitamins are classified as either fat-soluble or water-soluble. Fat-soluble vitamins cannot enter the blood stream directly, but must first bind to a lipid.

Minerals

• Like vitamins, minerals are not an energy source but are needed for normal metabolism. Since they are inorganic molecules, they are called "cofactors" instead of "coenzymes" but they are also needed for proper functioning of several enzymes. For example, over 100 enzymes use magnesium as a cofactor, and calcium is needed for diverse reactions throughout the body (such as blood clotting, nerve transmission, and muscle contraction)
• Minerals also add mechanical strength to bones. Bones act as a storage reservoir for minerals, and if they are lacking in the diet they will be taken out of bones, thus weakening the bones.

Objective #3
Distinguish between fat-soluble and water-soluble vitamins and describe some of the function
of different vitamins.

Organic molecules that we can't or don't make enough of, so we obtain them from our diet.
We make Vitamin D in our skin from sunlight
Vitamins A, D, E & K are all fat soluble and can only be digested, absorbed and transported in conjunction with fat.
Scurvy is from lack of Vitamin C. Later resolved with limes.
Vitamin A deficiency cause ulcers on the Cornea of the eye and can led to blindness.
Lack of Vitamin D can cause Rickets and Osteoporosis.
Folic acid helps reduce neural (spinal) tube birth defects. Found in prenatal Vitamins.


Objective #4
Health of Mitochondria

Define the the terms energy reserves and circulating energy substrates.
The molecules that can be oxidized for energy by the processes of cell respiration may be derived from the energy reserves of glycogen, fat, or protein. Since these molecules --- glucose, fatty acids, amino acids, and the others -- are carried by the blood to the cells for use in cell respiration, they can be called circulating energy substrates. FAT!!!!

Glycogen (mainly for muscles)
Protein (for emergency only)

The stuff that is available to the cells are:
- Glucose
- Fatty Acids
- Ketone Bodies
- Amino Acids

25,000 People die from starvation and 800 million are undernourished.
The united states has the highest rate of Obesity! This has doubled in Adults and Tripled in Children!
Risk for Heart disease
Body Mass Index
Complications of obesity

Objective #5
Describe the regulation of eating.

There are many regulators of hunger
- Several neurotransmitters in various regions of the brain.
- Nervous Signals from the stomach and the small intestines. (feeling full)
- Polypeptide Hormones released from digestive organs.
- Leptin (from fat) acts as a hormone to control eating patterns over a longer term

(but we become desensitized to it)

HORMONES
For women time of the month is a factor as well as pregnancy.Fat cells regulate Hunger and Metabolism.

Objective #6
Describe the regulation of adipocyte development and the roles of adipocytesin the regulation of hunger.

Leptin - Hormone Secreted by adipose tissue that acts as a safety factor to reduce appetite. It also increases the body's caloric expenditure.Leptin Fat cells have been cloned, yet are not widely used at this time.



Objective #7
Describe the actions of insulin and glucagon.

There are 2 major types of Diabetes

Diabetes Mellitus Type I (or insulin-dependent) Your body makes little or no insulin. Injections are required since insulin is a polypeptide and would be digested if taken orally. Recently FDA has approved an inhaler containing a fine powder of insulin for the control of type 1 diabetes in adults, although it is not being used for most patients yet. Diabetes Type I is a lot more difficult to treat. The patients are often brittle diabetics. Every child diagnosed with JDM (juvenile diabetes mellitus) has Type I and is insulin dependant, as their pancreas produces little or no insulin. One effect of Type 1 diabetes in that the body starts converting fatty acids into ketone bodies in the liver because the cells that need glucose are not taking in the glucose so they tell the body to make more glucose from fatty acids and that can cause ketosis or ketone acidosis.

Diabetes Mellitus Type II (non-insulin-dependent) Is slow to develop, can be hereditary and occurs most often in people who are over weight. Those people who have type 2 diabetes can have normal or even elevated levels of insulin in their blood . Despite seemingly normal insulin level, you can have hyperglycemia if untreated. The amount of insulin secreted is insufficient to control blood glucose levels. This type of Diabetes can be controlled with oral anti-diabetic medication, diet and exercise. The exercise will benifit type 2 because it will make your muscle cells more receptable to insulin.
Type 1 diabetes accounts for 5% and type 2 accounts for 95% of the diabetic population. The incidence of type 2 diabetes has tripled in the past 30 years, because of the increase in obesity. Diet and Exercise along with medications can control the symptoms in most people with type 2 diabetes.

The main reason for kidney disease is diabetes

Remember the osmotic gradient in the collecting duct of the kidneys. The collecting duct is where you are receptable to ADH and where you reabsorb the water to make the urine more concentrated. If you have too much glucose in the duct then it will ruin the osmotic gradient and so the water stays in the urine not letting the water absorb back into the blood stream. That will cause problems with blood volume and will cause dehydration.
INSULIN

insulin is produced by the pancreas in the beta cells and the alpha cells produce glucogan.

If you don't have insulin you become hyperglycemic

Insulin is the only way to lower blood sugar levels, but you have many ways to higher your blood sugar. Because this is a new problem that our body has not yet adapted to. So we need to be proactive in eating healthier and exercising.

Insulin secreations is stimulated be a rise in blood glucose consentrstion, and insulin promotes the entry of blood glucose

Questions
1. How does hypothermia affect our basal metabolic rate?
a. it lowers it dramatically
b. it raises it slightly c. it raises it dramatically
d. it is not affected

2. All of the following are important in influencing our BMR, except:
a. oxygen consumption while relaxed
b. age and gender
c. pancreatic secretions
d. physical activity

3. Scurvy is caused by a deficiency in what vitamin?
a. vitamin A
b. vitamin C
c. vitamin D
e. vitamin K

4. All of the following are soluble in fat except____________.
a. vitamin A
b. vitamin K
c. vitamin C
d. vitamin E
e. all of the above

5. An endurance athlete should receive most of their energy from which source?
a. protein
b. carbohydrate loading
c. water
d glucose
e. fat

6.Which of the following could be absorbed directly without need of digestion?
a. glucose
b. fat
c. polysaccharides
d. protein
c. nucleic acid

7. The amino acids that must be consumed in the diet are called essential. Nonessential amino acids.
a. can be produced by the body.
b. are only needed occasionally.
c. are stored in the body until needed.
d. can be taken in by supplements.

8. The hormone that is most important in the daily regulation of cell respiration is:
a. insulin
b. thyroxine
c. epinephrine
d. growth hormone

9.In a cold environment, the arterioles in the dermis will:
a. dilate to conserve heat
b. dilate to lose heat
c. constrict to conserve heat
d. constrict to lose heat

10. The basal metabolic rate is the term for the body's heat production when the body is:
a. in a stress situation
b. at rest
c. exercising strenuously
d. performing light activity

11. All of these vitamins are necessary for cell respiration except:
a. niacin
b. vitamin D
c. riboflavin
d. thiamin

12. A meal that consists of 20 grams of starch, 20 grams of protein, and 10 grams of fat has _____________ calories:
a. 220
b. 230
c. 240
d. 250

13. Vitamins can best be described as:
a. building blocks of new tissue
b. sources of energy
c. a chemical form of stored energy
d. chemicals often necessary for the functioning of enzymes


14. The term for synthesis reactions is:
a. metabolism
b. catabolism
c. anabolism d. metabolic rate
15. Which of the following is not a function of the liver in adults ?
a. Produces bile
b. Detoxifies alcohol.
c. Stores glucose.
d. Produces urea.
e. Makes red blood cells.

16. Metabolism is broken down into two chemical reactions
a. anabolism and canabolism
b. anabolism and catabolism
c. acidic and basic
d. intracellular and extracellular
e. none or the above

17. Glycogen and starch belong to the nutrient group known as____
a. mineral
b. polysaccharide
c. lipid
d. protein
e. carbohydrate

18. Which association is incorrect?
a. protein--trypsin
b. fat--bile
c.fat--lipase
d. maltose--pepsin
e. starch--amylase