The electrical impulse that initiates the heartbeat originates in which structure?

The electrical impulse that initiates the heartbeat originates in which structure?

• A. Atrioventricular node.
• B. Bundle of His.
• C. Sinoatrial node.
• D. Coronary sinus.

Answer: (C)

The starting point for the heart’s electrical rhythm is the Sinoatrial node. This cluster of pacemaker cells in the right atrium naturally generates electrical impulses, setting the pace for the heartbeat—typically about 60–100 beats per minute in a healthy adult. From there, the impulse travels through the atrioventricular node and onward into the His-Purkinje system to coordinate the timing of atrial and ventricular contractions. The AV node mainly provides a brief delay to ensure the ventricles fill before they contract, not the initiation of the impulse. The bundle of His conducts the signal deeper into the ventricles, and the coronary sinus is a venous channel draining blood from the heart muscle into the right atrium, not involved in starting the heartbeat.

The starting point for the heart’s electrical rhythm is the Sinoatrial node. This cluster of pacemaker cells in the right atrium naturally generates electrical impulses, setting the pace for the heartbeat—typically about 60–100 beats per minute in a healthy adult. From there, the impulse travels through the atrioventricular node and onward into the His-Purkinje system to coordinate the timing of atrial and ventricular contractions. The AV node mainly provides a brief delay to ensure the ventricles fill before they contract, not the initiation of the impulse. The bundle of His conducts the signal deeper into the ventricles, and the coronary sinus is a venous channel draining blood from the heart muscle into the right atrium, not involved in starting the heartbeat.