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Unformatted text preview: Chapter 23 – Circulation (1) Why do some animals have a circulatory system? • A circulatory system is necessary in any animal whose body is too large or too complex for vital chemicals to reach all its parts through diffusion alone. • The circulatory system provides an efficient long-distance internal transport system that brings resources close enough to cells for diffusion to occur. (2) How do some organisms live without one? Examples? • Some organisms can exchange materials directly with the water surrounding the organism to share throughout the organism, for example, a Hydra. (3) Distinguish between open and closed circulatory systems and give examples of each. • Open Circulatory System : a circulatory system in which blood is pumped through open ended vessels and out among body cells. In an animal without an open circulatory system, blood and interstitial fluid are one in the same. An example of an organism with an open circulatory system is a grasshopper. • Closed Circulatory System : a circulatory system in which blood is confined to vessels, and is kept separate from interstitial fluid. An example of an organism with a closed circulatory system is a fish. (4) How does the cardiovascular system of a fish differ from that of land vertabraes? • Fish breathe with gills, land vertebraes breathe with lungs • Fish have single circuit blood flow and 2 chambers (an atrium and a ventricle) • Land Vertabraes have 2 circuits (pulmonary circuit to lungs, and systemic circuit to the systemic capillaries). This is a double circulation. Land vertabraes also have 4 chambers (right atrium, right ventricle, left atrium, left ventricle) (5) Human Cardiovascular System: Explain the rold of each of the following… • Left and Right Atrium : heart chambers that receive blood from the veins • Left and right ventricles : heart chambers that pump blood out of the heart • Arteries : pump blood away from the heart • Veins : carry blood back to the heart • Capillaries : Microscopic blood vessels that convey blood between an artery and a vein, or between an arteriole and a venule. Enables the exchange of nutrients and dissolved gases between the blood and the interstitial fluid. • Arteriole : a vessel that conveys blood between an artery and a capillary bed • Venules : a vessel that conveys blood between a capillary bed and a vein....
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- Spring '07