IMED3001 Study Guide - Final Guide: Sinoatrial Node, Vagus Nerve, Atrioventricular Node
14 Dec 2020
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Left coronary artery is short and branches into left circumflex artery anterior interventricular artery. Right coronary artery is much longer and courses posteriorly. Coronary sinus delivers de- oxygenated blood from myocardium to right atrium. Vena cavae & coronary sinus open into right atrium. Sinoatrial (sa) node fires (~ 70 times / min) Cardiac muscle of right atrium conducts and contracts. Impulse travels from av node down the iv septum via av bundles. Av bundles branch to purkinje fibres that supply papillary muscles and walls of ventricles. Pre-synaptic sympathetic fibres from iml of t1-t5. Post-synaptic sympathetic fibres from cervical and superior thoracic sympathetic ganglia and end in sa and av nodes. Sympathetic stimulation:hr,force of contractions, (indirectly) dilates coronary arteries by inhibiting their constriction. => supplies more oxygen and nutrients to myocardium during increased activity. Pre-synaptic fibres from vagus nerves (cn x). Post-synaptic fibres from intrinsic ganglia located near sa and av nodes and along coronary arteries.
