Two kinds of cardiac cells The conduction system of the heart Interatrial septum Right and left bundle branches 1. The working cells Sinoatrial node (SA node) Atrioventricular pecial property node(Av node) contractility Atrioventricular bundle of His Purkinje fibers Interventricular septum Apex of heart4 1, The working cells. Special property: contractility Two kinds of cardiac cells