Physiology 2130 Study Guide - Final Guide: Pulmonary Artery, Pulmonary Vein, Pulmonary Circulation
24 Dec 2018
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70% of the tbvthe low pressure environment of these vessels requires the presence of venous valves to ensure that the blood flows in one direction only -- back to the heart. The sinoatrial (sa) node the sinoatrial node is located in the upper posterior wall of the right atrium. Sa nodal action potential (i) pacemaker potential - characterized by the slow spontaneous depolarization which is caused by: increased permeability to na + and ca 2+ decreased permeability of cells to k + (ii) depolarizing phase - at threshold (-40 mv), Bundle of his to the ventricular cellsventricles contract from the bottom up. Sa node atrial muscle av node bundle of his purkinje fibers ventricular muscle. P-wave - the depolarization of the atrial muscle, which causes the atria to contract. Qrs complex - depolarization of the ventricular muscle, which causes the ventricles to contract. T-wave - repolarization of the ventricular muscle, which causes the ventricles to relax.
