PHYSL212 Lecture Notes - Lecture 31: Parasympathetic Nervous System, Sympathetic Nervous System, Atrioventricular Node
4 Dec 2016
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Physl 212 - lecture #31 - cardiac electrophysiology pt. If ina fails, ica,l can cause depolarization ventricular contraction (time for atria to empty) preventing spontaneous activity. Autonomic nervous system and heart rate control: sympathetic (sns) Myocardial mechanisms for heart rate control: heart rate is governed by cardiodepressant (parasympathetic nervous system) and cardioaccelerator (sympathetic nervous system) influences, modulates the intrinsic pacemaker (sa node) The pns and the sns: vagus nerve (parasympathetic) Innervates the sa and the av node: sympathetic cardiac nerve (sympathetic) Heart rate = [ca2+] levels = force of contraction. In contractility = recognize [ca2+]in = force of contraction. Sympathetic vs parasympathetic mechanism: ***very important picture!! Parasympathetic influence (vagus: vagal input (ach release) frequency of sa node depolarization. Effects of sympathetic activity on ventricular contractility (ionotropic effect: vagal input + sns = catecholamine release (epinephrine, norepinephrine, ca2+ accumulation = incx activity = causes pacemaker potential. Heart rate: + ionotrope = [ca2+]in = force of contraction.
