The sequence of electrical events during one full contraction of the heart muscle:

• 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.

> 031. Components of the Conduction System_SA