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Chapter 14
Cardiac Output, Blood Flow, and Blood Pressure
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.
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.
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
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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-AType 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.
o Anti-B
o Anti-rH.
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."
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. 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.
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)
- 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
Latest page update: made by camanda
, Nov 21 2007, 1:16 AM EST
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| Started By | Thread Subject | Replies | Last Post | |
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| flattail | Funky formatting! | 0 | Nov 1 2007, 8:14 PM EDT by flattail | |
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Thread started: Nov 1 2007, 8:14 PM EDT
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I'm sure this probably started as an outline in Word or something, but it looks almost like poetry to have the bullet statements beginning with V and O and strange characters. I'm sure it will be changed over time, but I just wanted to comment that it looks quite interesting at the start.
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