Julia Choate; Week 10 MED1022
CV system is blood vessels and heart. Heart valves only permit a one way flow. AV valves can be mitral (bicuspid) between left atrium and ventricle or tricuspid between right. Papillary muscles anchor these valves. Aortic and pulmonary valves are semilunar. Left side of heart is high pressure, right side is low pressure. Mean pressure of left if 95mmHg, right is 15mmHg. Flow is proportional to change in pressure. It is directly proportional if the flow is laminar. Turbulent flow through diseased heart valves produces sound, usually known as heart murmurs. There is also resistance to flow, determined by the length of the tube, the viscocity of the fluid and the radius of the tube. Flow = delta P / R. Radius is the most variable volume, the other values stay relatively constant the whole time. Resistance is proportional to 1/r^4. Arteriole diameter is controlled by smooth muscle, contraction causes narrowing and relaxation causes widening. Skeletal muscle arteriole diameter is twice that going to the gut.