circulatory suummaryyyy

circulatory suummaryyyy - CIRCULATORY SYSTEM 1. Parts and...

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CIRCULATORY SYSTEM 1. Parts and functions In most multi-cellular animals, an internal transport system, or circulatory system, distributes nutrients and oxygen to the body cells and collects carbon dioxide and other metabolic wastes from the cells and brings them to their respective disposal sites. Man’s circulatory system consists of the following: a. circulating fluids (i.e., blood and lymph); b. a system of tubes, or vessels, through which blood or lymph flows; and c. a pumping organ, or heart, which pumps blood through the vessels The main functions of the circulatory system are: (a) to distribute nutrients and oxygen to the body cells and (b) to collect carbon dioxide and other metabolic wastes from the cells and bring them to where the body can get rid of them. 2. Blood and its solid components Blood is a fluid pumped through the body by the heart. Blood supplies all body cells with oxygen and nutrients. The cells use oxygen to release the energy contained in the nutrients. Blood also carries waste products away from the cells. Waste products can be carbon dioxide, salts, or excess water. Blood is made up of red blood cells , white blood cells , platelets , and plasma . Red blood cells transport oxygen. They get their color from a substance inside them called hemoglobin . Hemoglobin carries oxygen. It turns red when it is holding oxygen. White blood cells help fight infection. They destroy bacteria and viruses that invade the body. Platelets help heal wounds. Plasma is the fluid part of the blood. Plasma carries blood cells and platelets, digested food, and water through the circulatory system. 3. Blood vessels and blood flow Blood moves through the body in blood vessels. Arteries are blood vessels that move oxygen-rich blood from the heart to the rest of the body. The heart pumps blood through the arteries at high pressure. The arteries’ walls are thick in order to withstand this pressure. Veins carry oxygen-poor blood back to the heart. The blood in the veins flows under less pressure. Veins have valves that keep the blood flowing in one direction. Capillaries are very tiny blood vessels that lie between arteries and veins. Every cell in
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the body is near a capillary. As blood travels through the capillaries, nutrients and oxygen move from the blood into the body cells. All the same time, carbon dioxide and other wastes move from the body cells into the blood. Blood returning to the heart through the veins has given up its oxygen to the body cells. This blood enters the right side of the heart and is pumped to the lungs. As it moves through the capillaries in the lungs, it absorbs oxygen and releases carbon dioxide. Then it travels to the right side of the heart. From there, the oxygen-rich blood is pumped throughout the body.
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This note was uploaded on 07/19/2011 for the course SC 101 taught by Professor David during the Fall '10 term at American Intl. University.

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circulatory suummaryyyy - CIRCULATORY SYSTEM 1. Parts and...

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