01:377:370 Lecture Notes - Lecture 25: Atrioventricular Node, Qrs Complex, Chronotropic
11 Apr 2019
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Electrochemical rhythms spread from sa node across atria to atrioventricular node. Av node causes a slight delay of ~0. 1 sec. Transmits impulse through ventricles over specialized conducting fibers (pirkunj) These fibers form distinct right and left bundle branches. Can transmit impulse 6x faster than normal ventricular muscle fibers. Provides for unified and simultaneous contraction of both ventricles. A recording of the heart"s electrical activity. A standard system of lead placement has established known wave patterns. Represents depolarization of the atria; lasts ~0. 15 seconds and signals atrial contraction. Represents ventricular depolarization and signals ventricular contraction. Atrial repolarization occurs as well, but is hidden in larger qrs complex. Represents ventricular repolarization; occurs during ventricular diastole. Hr changes rapidly through direct neural input and circulating chemical messengers. These extrinsic controls accelerate the heart in anticipation of exercise and then rapidly adjust to the intensity demands. Stimulation of sympathetic nerves release of catecholamines (e/ne) Can cause heart to beat faster (chronotropic effect)
