BILD 26 Lecture Notes - Lecture 8: Purkinje Fibers, Atrioventricular Node, Vagus Nerve
Document Summary
The main pacemaker in the heart is called the sa node. o sa node will generate action potentials that excite the contractile fibers in the atria, causing them to contract first. o upon contraction, the signal is transmitted into the av node, where the action potentials are conducted through the bundle of his. One way to increase co is during exercise, where sympathetic activation will increase the rate of pacemaker potentials, causing an increase in heart rate. o some elite athletes can increase co by up to 25 30l/min or more. If heart rate is too high, the stroke volume will be low, and the heart will not get enough oxygen because it is not getting enough time for blood to fill ( venous return). o however, exercising will make cardiac muscles stronger and increase contractility heart will be able to pump out more blood in a single beat ( stroke volume).
