2, Special conduction system including h The conduction system of the heart Sinoatrial nodes Interatrial septum Atrioventricular Right and left bundle branches node Sinoatrial node. (SA node) Atrioventricular Atrioventricular node(Av node) TU N bundle(bundle of Atrioventricular bundle His) (bundle of His and Purkinje Nancy Marshburn system Purkinje fib Interventricular septum Apex of heart Special property automaticity5 including the Sinoatrial node, Atrioventricular node, Atrioventricular bundle (bundle of His), and Purkinje system. Special property: automaticity 2, Special conduction system