What part of the heart is known as the pacemaker?

What part of the heart is known as the pacemaker?

• A. AV node
• B. Bundle of His
• C. SA node
• D. Ventricular foci

Answer: (C)

The sinoatrial (SA) node is referred to as the heart's natural pacemaker because it generates electrical impulses that trigger heartbeats. Located in the right atrium, the SA node sets the rhythm for the entire heart by determining the rate of contractions. It is responsible for initiating each heartbeat, which then propagates through the heart's conduction system, ensuring that the atria contract before the ventricles are stimulated.

This structure has the highest intrinsic firing rate compared to other parts of the conduction system, like the AV node or the Bundle of His, which serve as conduction pathways but do not initiate impulses themselves. While the ventricular foci can act as pacemakers if both the SA and AV nodes fail, they typically fire at a slower rate and are not the primary regulators of heart rate. Thus, the SA node's role as the primary and dominant pacemaker is essential for maintaining a regular and coordinated heartbeat.