What is the primary function of the AV node in atrioventricular conduction?

What is the primary function of the AV node in atrioventricular conduction?

• A. To initiate the heartbeat
• B. To delay conduction between atria and ventricles, allowing ventricular filling
• C. To accelerate conduction to the ventricles
• D. To regulate heart rate via autonomic input

Answer: (B)

The main function of the AV node is to slow the electrical impulse as it moves from the atria to the ventricles, creating a delay that lets the atria finish contracting and fill the ventricles before they contract. This gating ensures coordinated timing in the cardiac cycle and efficient ventricular filling. The delay comes from the AV node’s slower conduction properties and its longer refractory period, which also helps protect the ventricles from very rapid atrial rhythms. The SA node, not the AV node, initiates the heartbeat. The AV node does not speed up conduction to the ventricles; it slows it. Autonomic input can influence how fast or how long the AV node holds the impulse, thereby modulating heart rate, but the primary role of the AV node is to provide that crucial delay between atrial and ventricular contraction.

The main function of the AV node is to slow the electrical impulse as it moves from the atria to the ventricles, creating a delay that lets the atria finish contracting and fill the ventricles before they contract. This gating ensures coordinated timing in the cardiac cycle and efficient ventricular filling. The delay comes from the AV node’s slower conduction properties and its longer refractory period, which also helps protect the ventricles from very rapid atrial rhythms.

The SA node, not the AV node, initiates the heartbeat. The AV node does not speed up conduction to the ventricles; it slows it. Autonomic input can influence how fast or how long the AV node holds the impulse, thereby modulating heart rate, but the primary role of the AV node is to provide that crucial delay between atrial and ventricular contraction.