What is the pacemaker of the heart?

The sinoatrial (SA) node is referred to as the pacemaker of the heart because it is primarily responsible for initiating and regulating the electrical impulses that trigger each heartbeat. Located in the right atrium, the SA node generates electrical signals at regular intervals, typically around 60 to 100 beats per minute in a resting adult. This natural pacemaking activity sets the rhythm of the heart and ensures that the heart beats in a coordinated and efficient manner.

The impulse from the SA node spreads through the atria, causing them to contract and push blood into the ventricles. Following this, the electrical signal reaches the atrioventricular (AV) node, which acts as a relay point before the impulse travels through the Bundle of His and the Purkinje fibers to stimulate the ventricles to contract. However, it is the SA node that establishes the initial rate of heart contractions, making it the primary pacemaker.