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Unformatted text preview: Chapter 14:Blood Vessels, Flow &amp; Pressure Flow Rule Circulatory system = closed system Pressure = force exerted by blood Flow occurs from high pressure to low pressure Flow= Delta P/R Blood Vessels Arteries relatively large, branching vessels that conduct blood away from the heart Arterioles small branching vessels with high resistance Capillaries site of exchange between blood &amp; tissue Venules small converging vessels; have valves Veins relatively large converging vessels that conduct blood to the heart Closed system because the blood stays within the vessels, Pressure Gradients in the Cardiovascular System Pressure gradients drive flow from high pressure to low pressure Flow due to pressure gradients= bulk flow Heart- creates pressure gradient for bulk flow of blood A gradient must exist throughout circulatory system to maintain blood flow Aorta is largest! Pressure Gradient Across Systemic Circuit Pressure gradient = pressure in aorta minus pressure in vena cava just before it empties into right atrium MAP- CVP Pressure in aorta = mean arterial pressure (MAP) = 90mmHg Pressure in vena cava = central venous pressure (CVP) = 0 Pressure gradient = MAP CVP = 90-0 Figure 14.2 Pressures and Pressure Drops in the Pulmonary and Systemic Circuits Why does pulmonary have such a small Resistance in the Cardiovascular System Pressure gradient in systemic circuit much greater than for pulmonary circuit Flow through both circuits equal Flow = delta P/R Resistance through pulmonary circuit much less than through systemic circuit Effect of resistance on Flow 14.4 High resistance vs low Think of having a straw, who can sip at the fastest rate. Large diameter will win if same length and substance is of same viscosity Factors Affecting Resistance to Flow Radius of vessel In arterioles (and small arteries) - can regulate radius- can regulate radius Length of vessel Viscosity of fluid = Blood viscosity dependent on amount of RBCs and proteins Regulate Blood Flow by Regulating Radius Regulation of radius of arterioles (and small arteries)...
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This note was uploaded on 04/08/2008 for the course BIOL 2160 taught by Professor Kt during the Spring '08 term at LSU.
- Spring '08