Which structure is known as the pacemaker of the heart?

The sinoatrial node (SA node) is recognized as the primary pacemaker of the heart because it initiates the electrical impulses that dictate the heart rate and rhythm. Located in the right atrium near the entrance of the superior vena cava, the SA node generates electrical signals that cause the atria to contract and push blood into the ventricles. This function is crucial for maintaining a consistent and efficient heartbeat.

The intrinsic rhythmicity of the SA node is due to its unique cells, which have a natural ability to depolarize spontaneously. As the main pacing site, it regulates the overall heart rate by responding to the body's varying demands, adjusting the heart rates in response to factors like physical activity or rest.

In contrast, while the atrioventricular node, Bundle of His, and Purkinje fibers are involved in the conduction system of the heart, they serve different roles. The atrioventricular node acts as a gatekeeper, slowing the electrical signal before transmitting it to the ventricles, and the Bundle of His and Purkinje fibers distribute the electrical impulse throughout the ventricles to promote coordinated contraction. These structures do not generate impulses with the regularity or authority of the SA node, which is why they are not considered the