Circulation%201 - Circulation The proper functioning of...

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Circulation The proper functioning of cells (and organs) in a multicellular animal is dependent upon control of perfusion rates. A circulatory system basically consists of a central pumping mechanism connected to the tissue via a tubing system--the system can be either open or closed In the vertebrates, the number of heart chambers and the pattern of circulation depends upon whether you use a gill or lung as the gas exchanger. Amphibians have a circulatory system that mixes oxygenated and unoxygenated blood. Remind yourselves of the basic circulatory system of the mammal . The vascular system in mammals consists of arteries, arterioles, capillaries, venules, and veins. The structure of a particular vessel depends upon the thickness of the vascular smooth muscle that surrounds the vessel. Note that the endothelium is a thin layer of cells that lines the lumen of all the blood vessels. Because of an increased cross sectional area , blood flow and pressure falls in the arterioles and reaches very low levels in the
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Circulation%201 - Circulation The proper functioning of...

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