Physiology 2130 Lecture Notes - Lecture 9: Stroke Volume, Vasomotor Center, Autoregulation
28 Mar 2017
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Document Summary
A closed system of tubes (blood vessels) filled with a fluid (blood) moved around by a central pump (heart) Arteries to arterioles to capillaries to venules to veins: capillaries: the smallest type of blood vessel, and the functional unit of the circulatory system, where substances enter and leave. Total blood volume: 5 l: 70% is contained within the veins o. 15% is contained within the heart and lungs. 5% is contained within the capillaries o o. Blood reservoir: the veins, because they have the highest capacity to carry blood. Arteries: highest blood pressure and velocity, but a low-cross sectional area: distribute blood rapidly due to these properties. Arterioles: lower blood pressure, but higher cross-sectional area: site of highest resistance in the circulation to help regulate blood flow to an organ. Capillaries: lowest blood velocity, and highest cross-sectional area: maximize exchange of substances across them. Venules: blood pressure and cross-sectional area decrease.
