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Cardiovascular System Chronotropic Effects of the Autonomic Nervous System * The nervous system only modulates the heart beat but does not initiate it. * cardiac center of the medulla consist of two neuronal pools * cardioacceleratory center- sends signals by way of the sympathetic cardiac accelerator nerves to the SA node, AV node, and myocardium. * These nerves secrete norepinephrine, which bind to B-adrenergic receptors that tend to increase heart rate and contractility Chronotropic Effects of the Autonomic Nervous System * Cardioinhibitory center- sends signals by way of the parasympathetic fibers in the vagus nerves to the SA and the AV nodes] * the right vagus innervates mainly the SA node and the left vagus, the AV node * nerve secretes acetylcholine which binds to muscarinic receptors to opens K+ channels (K+ leaves the cell) to hyperpolarize the cell which causes the cell to fire less frequently, thereby slowing the heart rate.
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.
- Fall '10