EHS 385 Lecture Notes - Lecture 26: Bradycardia, Atrioventricular Node, Exercise Physiology
2 Jan 2019
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Amount blood pumped by heart each minute. Determined by: heart rate, number of heartbeats/minute, stroke volume, amount blood ejected from heart w/ each beat. Cardiac output (q) = heart rate x stroke volume. Intrinsic heart rate + 100 beats/min: heart not stimulated by ans. Increase pns = slow heart rate decreasing sinoatrial and atrioventricular node activity. Sympathetic nervous system: trough cardiac accelerator nerves. Increase sns activity increase heart rate by stim sa and av node activity. Rest: low resting heart due to high pns activity. Increase in heart rate due to decrease in pns activity: up to 100 bets per minute. Further increase in heart rate due to increased sns activity: up to max heart rate. End diastolic volume: vol of blood in ventricles, preload. Average aortic blood pressure (map: pressure against heart must pump to eject blood into systemic circulation, afterload. Strength of ventricular contraction: enhanced by sympathetic stim of heart.
