BIOL3030 Lecture Notes - Lecture 23: Check Valve, Elastic Fiber, Blood Pressure
7 Nov 2016
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Document Summary
Heart pumps blood in a pressurized fluid: check valve when blood exits the heart to prevent blood from re-entered into the heart. Pressure reservoir: blood pressure does not drop to zero, as we go towards the capillaries, the oscillations start to dampen, venous system does not have elastic tissue, hallmark of vertebrate cardiovascular system, bulbus arteriosis. Jet that pushes blood through the heart. Capillaries: the pressure is reduced when blood gets to capillaries, cannot fend off osmotic pressure which causes an exchange of nutrients into the blood. Only because capillaries are very thin: comprised of 2 cells. Cross-section is only comprised of 1 cell. Precapillary sphincter: at the arterial junction, round muscle that contracts and constrict to allow more blood to pass into the capillary or keep blood out of the capillary, relax and let more blood in too. Blood moves in a single return from the heart and back to the heart.
