BIOLOGY 2A03 Lecture Notes - Lecture 12: Ejection Fraction, Vagal Tone, Autonomic Nervous System
13 Mar 2018
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Document Summary
Heart rate (hr) affected by changes in rates of ap generated by the pacemaker. Pace makers are innervated by autonomic nervous system (ans) Sns and psns nervous systems have opposite effects on the heart. Acts on 2 adrenergic receptors in sa node to increase hr. Acts on m2 muscarine receptors in sa node to decrease hr. "vagal tone" from psns predominates at rest - reduces hr below the endogenous rate of the. Sns and pns affect hr by changing the rate of spontaneous depolarization (dictated by background leak permeabilities), not by altering the shape of duration of the ap. Stroke volume is affected by the sns (not psns) Sns innervation of conduction fibres increases the speed of signal propagation (increases the time available for cardiac filling during diastole) Sns innervation of contractile fibres increases the force of contraction. Activation of 1 adrenergic receptors in contractile fibres enhances various components of ca2.
