PSL301H1 Lecture Notes - Lecture 8: Tachycardia, Myocyte, Stethoscope
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PSL301H1 Full Course Notes
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Heart is stimulated by the sympathetic cardioacceleratory system. Stronger force of contraction on atrial and ventricular chambers. Heart is inhibited by the parasympathetic cardioinhibitory system. Ach acting on gi-protein mesocranic receptor via vagal nerves on sa node to reduce camp production as well as causing k+ to leak out. Cardiovascular control center in the medulla oblongata. Increase of k+ efflux, decrease of ca2+ influx. Hyperpolarizes cell and slows the rate of depolarization. Activates camp second messenger system resulting in phosphorylation of. 1) voltage gated ca2+ channels (dihydropyridine receptor) Ca2+ entry from the ecf increase storage of ca2+ in sr and increase ca2+ surge leading to a more forceful contraction. 2) phosphorylation of phospholamban (accessory molecule, inhibitor of the srer calcium atpase that is the pump in the. Ca2+ removed from cytosol faster into sr. Shorter ca-troponin binding time shorter duration. Mechanical pumping events of the cardiac cycle. The heart cycles between contraction (systole) and relaxation (diastole)
