PSL301H1 Lecture Notes - Lecture 9: Stroke Volume, Myocyte, Cardiac Output
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PSL301H1 Full Course Notes
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Lecture 9: regulation of cardiac output: esv ~65 ml, provides safety margin to be able to send additional blood to tissues, edv ~135 ml. Stroke volume (sv): amount of blood pumped by 1 ventricle in 1 contraction, edv-esv: not constant, can increase during exercise, indicates force of contraction. Cardiac reserve: maximal co - resting co: increased isotropy = increased sv/decreased esv. Skeletal muscle pump: skeletal muscle contractions squeeze veins helps return blood to heart in exercise. Sympathetic constriction: decreased volume squeezes more blood into heart larger ventricular volume = forceful contraction = sent to arterial circulation allows body to redistribute venous blood to arterial circulation. Low compliance, low capacitance: resistance at arterioles/capillaries where gas/nutrients exchanged at tissues, 65-80% of blood in large veins (vena cava, etc. ) Phospholamban: ca-atpase on sr increases, ca out of cytosol faster, shorter ca-troponin binding time shortens contraction duration.
