1. The four basic components of any circulatory system are a vehicle, conduits, a motive force, and exchange areas. The vehicle is the substance which actually carries the materials being transported. A conduit is a channel, pipe, or tube through which a vehicle travels. If we say that a force is motive, we mean that it produces movement. Systems providing a motive force are often known as pumps. Exchange areas exist so that materials being transported may be eventually exchanged with a part of the body. (para 9-2)
2. The human cardiovascular system is a collection of interacting structures designed to supply oxygen and nutrients to living cells and to remove carbon dioxide and other wastes. Its four major components are the blood, blood vessels, heart, and capillaries. The vehicle is the blood. The conduits are the blood vessels. The primary motive force is provided by the heart. The exchange areas are provided by minute vessels called capillaries. (para 9-4)
3. The major subdivisions of blood are the plasma and the formed elements. Plasma makes up about 55 percent of the total blood volume. Plasma is mainly composed of water. Among the most important materials dissolved in plasma are proteins. After the blood clots, the clear fluid remaining is serum, which does not contain the proteins used for clotting. Otherwise, it is very similar to plasma. (para 9-5)
4. The formed elements of the blood make up about 45 percent of the total blood volume. While red blood cells and white blood cells are cells, the platelets are only fragments of cells. What is the shape of an RBC? Biconcave disc. In a cubic millimeter of normal blood, there are about 5,000,000 RBCs. RBCs contain a protein called hemoglobin, which transports most of the oxygen carried by the blood. (para 9-5b)
5. The most common types of white blood cells are neutrophils and lymphocytes. Neutrophils phagocytize foreign particles and organisms. Lymphocytes produce antibodies. In a cubic millimeter of normal adult blood, there are about 5,000 to 11,000 WBCs. (para 9-5b(2))
6. The main function of platelets is to aid in clotting by clumping together and by releasing chemical factors related to clotting. In a cubic millimeter of normal blood, there are about 150,000 - 350,000 platelets. (para 9-5b(3))
7. Four general functions of blood are:
a. Serving as a vehicle.
b. Aiding in temperature control.
c. Protecting our bodies by providing immunity.
d. Blood clotting. (para 9-5c)
8. The inner, smooth epithelial layer of a blood vessel is called the intima. The middle layer of smooth muscle tissue is called the media. The outer layer of FCT is the adventitia. (para 9-6a)
9. The three types of blood vessels are arteries, veins, and capillaries. The arteries carry blood away from the chambers of the heart. The veins carry blood toward the chambers of the heart. Capillaries have extremely thin walls so that exchanges can take place between the blood and tissue cells. (para 9-6b)
10. The heart chambers are the four cavities into which the heart is divided. The atria are the upper two chambers of the heart. Each atrium has an ear-like projection known as an auricle. The ventricles are the lower two chambers of the heart. Between the two atria is a common wall known as the interatrial septum. Between the two ventricles is a common wall known as the interventricular septum.
11. The three layers in the walls of the heart chambers are the endocardium, the myocardium, and the epicardium. The inner layer is a smooth epithelium. The middle layer is made up of cardiac muscle tissue. The outer layer is another epithelium. (para 9-7a(2))
12. The atrial walls are relatively thin. The right ventricular wall is much thicker than the atrial walls. The left ventricular wall is three to five times thicker than the right ventricular wall. (para 9-7a(3))
13. The valve between the atrium and ventricle of each side is the atrioventricular (A-V) valve. The right A-V valve is known as the tricuspid valve. The left A-V valve is known as the mitral valve. The fibrous cords attached to the underside of the A-V valves are called chordae tendineae. They are attached to the inner walls of the ventricles by papillary muscles. (para 9-7a(4)(a))
The valve at the base of the pulmonary trunk and the valve at the base of the aortic arch are both semilunar valves, each with three cusps. They are often called the pulmonary valve and the aortic valve. (para 9-7a(4)(b))
14. Extrinsic nervous control of the heart is exerted by nerves of the autonomic nervous system. Speeding the heart up are the sympathetic cardiac nerves. Slowing the heart down is the vagus parasympathetic nerve. (para 9-7b(1))
Intrinsic "nervous" control is built within the heart. It consists of the sinoatrial (S-A) node, the atrioventricular (A-V) node, and the septal bundles. (para 9-7b(2))
For humoral control, there appears to be substances in the blood itself which have varying effects upon the functioning of the heart. (para 9-7b(3))
15. The coronary arteries supply "nutritive" blood to the heart walls. The coronary arteries arise from the base of the aortic arch and are spread over the surface of the heart. This blood is collected by the cardiac veins, which empty into the right atrium of the heart. If a coronary artery becomes closed, the receiving area of the heart will probably die. (para 9-7c)
16. The pericardium is a special serous sac surrounding the heart and reducing the frictional forces upon its moving surfaces. (para 9-7d)
17. The human cardiovascular system is closed because at no place is whole blood ever outside the system. It is two-cycle because the blood passes through the heart twice with each complete circuit of the body. In the pulmonary cycle, the blood passes from the right heart, through the lungs, and to the left heart. In the systemic cycle, the blood passes from the Jeft heart, through the body in general, and returns to the right heart. (para 9-8a)
18. In the case of collateral circulation, if one blood vessel to an area is damaged, then another blood vessel will continue the supply. However, when an end artery is damaged, the receiving area will usually die. (para 9-8a(3))
19. PULMONARY CYCLE: The pulmonary cycle begins in the right ventricle. Contraction of the wall of the right ventricle forces the tricuspid valve to close. This keeps blood from flowing back into the right atrium. The pressure forces blood past the pulmonary semilunar valve into the pulmonary trunk. Upon relaxation of the right ventricle, back pressure of the blood in the pulmonary trunk closes the pulmonary semilunar valve. The blood then passes into the lungs through the pulmonary arterial system. Gases are exchanged between the alveoli of the lungs and the blood in the capillaries next to the alveoli. The oxygenated blood is collected by the pulmonary veins and carried to the left atrium of the heart. (para 9-8b)
20. SYSTEMIC CYCLE: Oxygenated blood is moved from the left atrium into the left ventricle. Contraction of the wall of the left ventricle closes the mitral valve, which prevents blood from returning to the left atrium. The pressure forces blood past the aortic semilunar valve into the aortic arch. Upon relaxation of the left ventricular wall, back pressure of the blood in the aortic arch closes the aortic semilunar valve. The blood then passes through the various arteries to the tissues of the body. Materials are exchanged between the blood and cells of the body in the capillary beds. The blood returns to the right atrium of the heart in vessels called veins. (para 9-8c)
21. The head is supplied by the carotid arteries. The neck and upper members are supplied by the subclavian arteries. The aortic arch continues as a large single vessel known as the aorta. At the lower end of the trunk, the aorta divides into the right and left iliac arteries, supplying the pelvic region and lower members.
22. Running parallel to the arteries is the system of deep veins. Immediately beneath the skin is a network of superficial veins. These veins collect and then join the deep veins in the axillae (armpits) and the inguinal region (groin).
Collecting the blood from the head, neck, and upper members is the superior vena cava. Collecting the blood from the rest of the body is the inferior vena cava. Thus, the final major veins, emptying the returned blood into the right atrium of the heart, are the venae cavae. (para 9-8c(4)(c))
Except the veins from the head, veins are generally supplied with valves to assist in making blood flow toward the heart. (para 9-8c(4)(d))
Carrying absorbed substances from the gut to the liver is the hepatic portal venous system. After being specially treated and conditioned, this blood is returned to the general circulation by the hepatic veins. (para 9-8c(4)(e))
23. Located in the interstitial spaces, where they absorb excess interstitial fluid, are the lymphatic capillaries. A tributary system collects this fluid, now called lymph. To help maintain lymph flow in one direction, lymphatic vessels are supplied with valves. The major lymph vessel (which passes from the abdomen, up through the thorax, and into the root of the neck) is the thoracic duct. Lymph nodes are special structures which interrupt lymphatic vessels and serve as special filters for the lymph fluid passing through. Tonsils are special collections of lymphoid tissue. They are protective structures located primarily at the entrances of the respiratory and digestive systems. (para 9-10)
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