Which part of the heart conduction system is stimulated after the Sinoatrial (SA) Node?

The Sinoatrial (SA) Node is known as the natural pacemaker of the heart, responsible for initiating the electrical impulse that stimulates the heartbeat. After the SA Node fires an impulse, the next part of the heart conduction system to be stimulated is the Atrioventricular (AV) Node.

The AV Node acts as a critical relay station between the atria and the ventricles. It receives the electrical impulse from the SA Node and briefly delays it before transmitting it further down the conduction pathway. This delay is essential as it allows the atria to fully contract and empty their blood into the ventricles before the ventricles contract.

This sequential activation ensures that the heart beats in a coordinated manner, maintaining an effective pumping action. The Bundle of His, Purkinje fibers, and the ventricles are stimulated subsequently in this conduction pathway, but the AV Node is the immediate next structure activated after the SA Node.