BIOL 1119 Study Guide - Midterm Guide: Afterload, Inotrope, Heart Valve
29 Dec 2016
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Blood born ne and e (catecholamines: same potent adrenergic cardiac effects as ne from the sympathetic nerves. Other chemical impact hr through the catecholamine camp mechanism. Hormones: th increases adrenergic receptors in nodal cell and cardiocytes increases the making of the receptor protein increases sensitivity to adrenergic stimulation (stimulates up-regulation of adrenergic receptors) Electrolytes (k has the greatest effect: hyperkalemia. Normally k leaves the cell excess extracellular k tends to want to diffuse into cardiocytes and nodal cells less leaks out. If rise in extracellular k is slow, the membrane voltage stays elevated inhibits repolarization of the sa node and cardiocytes. Myocardium is less excitable, hr slows and is irregular. Slow rise in extracellular k has little effect on the start of depolarization of cardiocytes because much more positive comes in during depolarization due to the rapid influx of na. Depolarization plateau at peak of ap is longer.
