Describe the electrical conductance system of the heart?

An excitation signal (an action potential) is created by the sinoatrial (SA) node.The wave of excitation spreads across the atria,causing them to contract.Upon reaching the atrioventricular (AV) node, the signal is delayed.It is then conducted into the bundle of His, down the interventricular septum.The bundle of His and the Purkinje fibres spread the wave impulses along the ventricles, causing them to contract.