What component of the conduction system is referred to as the pacemaker of the heart?

A. Sinoatrial (SA) node: The SA node is known as the natural pacemaker of the heart because it initiates electrical impulses that regulate the heartbeat. Located in the right atrium, the SA node generates impulses that cause the atria to contract and set the pace for the heart rate. This function is essential for maintaining a normal sinus rhythm. B. Bundle of His: The Bundle of His, also known as the atrioventricular bundle, is part of the conduction system that transmits electrical impulses from the AV node to the bundle branches. While it plays an important role in conducting impulses, it does not initiate them and is not referred to as the pacemaker. C. Atrioventricular (AV) node: The AV node is responsible for receiving impulses from the SA node and delaying them briefly to allow the ventricles to fill with blood before contracting. Although it can act as a secondary pacemaker if the SA node fails, it is not the primary pacemaker of the heart. D. Bundle branches: The bundle branches carry electrical impulses from the Bundle of His to the ventricles, causing them to contract. They do not initiate impulses and therefore are not considered the pacemaker of the heart.