Chapter_14_Blood_Vessels

Chapter_14_Blood_Vessels - Chapter 14 Blood Vessels, Flow &...

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Chapter 14 Blood Vessels, Flow & Pressure Flow Rule Circulatory system = closed system Pressure = force exerted by blood Flow occurs from high pressure to low pressure Flow = ΔP/R 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 of blood A gradient must exist throughout circulatory system to maintain blood flow Pressure Gradient Across Systemic Circuit Pressure in aorta = mean arterial pressure (MAP) = 90 mm Hg Pressure in vena cava = central venous pressure (CVP) = ) mm Hg Pressure Gradients in Systemic Circuit 14.2 Pressures and Pressure Drops in the Pulmonary and Systemic Circuits 14.3 Resistance in the Cardiovascular System Pressure gradient in systemic circuit much greater than for pulmonary circuit Flow through both circuits equal Flow = ΔP/R Resistance through pulmonary circuit much less than through systemic circuit Effect of Resistance on Flow Factors Affecting Resistance to Flow Radius of vessel In arterioles (and small arteries) - can regulate radius Length of vessel Viscosity of fluid = η Blood viscosity dependent on amount of RBCs and proteins Regulate Blood Flow by Regulating Regulation of radius of arterioles (and small arteries) Vasoconstriction decrease radius increases resistance Vasodilation
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increase radius decrease resistance Pulmonary circuit less resistance than systemic lower pressure gradient required for blood flow Relating Pressure Gradients and Resistance in the Systemic Circulation Flow = cardiac output = CO ΔP = mean arterial pressure = MAP R = total peripheral resistance = TPR CO = MAP/TPR Neural Control of MAP Negative feedback loops Detector = Integration Center = Controllers = Effectors = Arterial Baroreceptors Baroreceptors = stretch receptors Arterial baroreceptors High pressure baroreceptors Sinoaortic baroreceptors Location Carotid sinus Aortic arch Example of the Baroreceptor Reflex in Action: Hemorrhage Hemorrhage decrease in blood volume Decrease in MAP Baroreceptor reflex quickly compensates for changes in blood pressure It does not correct problem Long-term regulation occurs through renal regulation of blood volume CV Responses to Exercise Blood Vessels Heart→arteries→arterioles→capillaries→venules→veins Arteries – relatively large, branching vessels that conduct blood away from the heart Arterioles – small branching vessels with high resistance Venules – small converging vessels; have valves
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Veins – relatively large converging vessels that conduct blood to the heart
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This note was uploaded on 05/12/2011 for the course BIOL 2160 taught by Professor Kt during the Fall '08 term at LSU.

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Chapter_14_Blood_Vessels - Chapter 14 Blood Vessels, Flow &...

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