Which component of the heart's conduction system helps coordinate the timing of heart contractions?

• A. SA Node
• B. AV Node
• C. Purkinje Fibers
• D. Bundle of His

Answer: (B)

Coordinating the timing of heart contractions relies on an electrical delay that lets the atria finish their squeeze before the ventricles kick in. The AV node sits between the atrial and ventricular conduction pathways and introduces a short delay to the impulse. That pause ensures atrial contraction is completed and ventricular filling occurs before ventricular contraction begins, giving the heart coordinated, efficient pumping.

The SA node acts as the natural pacemaker, setting the overall rate. The Purkinje fibers distribute the impulse quickly through the ventricles to synchronize their contraction, and the Bundle of His carries the impulse from the AV node to the Purkinje system. But the key coordinating delay comes from the AV node, making it the best answer.