HP 127 Lecture Notes - Lecture 11: Mean Arterial Pressure, Stroke Volume, Vascular Resistance
5 Mar 2019
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In the arteries, capillaries are essentially a tube of endothelial cells (so pressure needs. Increase/decrease heart rate- cardiac output to be low, to keep them intact, veins also have very low pressure) Blood flow (f) and the bp gradient ( p) F= p/r (mean arterial pressure divided by resistance = flow) Fluid in the tube: blood, vascular system: tube. Fact: blood flow to the pulmonary system (r. vent. ) is identical to arterial blood flow (l. vent) at rest. Fact: the pressure gradient is much lower in the pulmonary system than in the arterial circulation. Question: if the pressure gradient is the driving force behind blood flow, then how is it possible to have the same flow but greatly different pressure gradients? the same while having greatly different pressure gradients. Factors aiding venous return: 4 ways: skeletal muscle contraction: skeletal muscle pump, vasoconstriction, valves: prevent backflow of blood, respiration: respiratory pump (diaphragm and other respiratory muscles)
