Which electrical structure of the heart starts each heartbeat and is often called the "pacemaker" of the heart?

The sinoatrial node, often referred to as the "pacemaker" of the heart, is responsible for initiating each heartbeat. Located in the right atrium, the sinoatrial node generates electrical impulses that spread through the atria, causing them to contract and push blood into the ventricles. This function is crucial for maintaining a regular heart rhythm and determining the heart rate.

The sinoatrial node effectively sets the pace for the heart by controlling the timing of the heart's contractions. It acts as a natural pacemaker because it automatically fires electrical impulses without the need for external signals. As a result, it plays a key role in coordinating the heartbeat and ensuring that the heart maintains an efficient pumping action.

Other structures, like the atrioventricular node, bundle of His, and Purkinje fibers, work in conjunction with the sinoatrial node but are not the primary source of rhythmic impulse generation. The atrioventricular node serves as a relay point for impulses from the sinoatrial node, and the bundle of His and Purkinje fibers are involved in conducting those impulses throughout the ventricles to ensure they contract properly. However, it is the sinoatrial node that initiates the electrical activity that leads to each heartbeat