Which component delays the heart's electrical impulse between the atria and ventricles to allow ventricular filling?

Which component delays the heart's electrical impulse between the atria and ventricles to allow ventricular filling?

• A. AV node
• B. SA node
• C. Purkinje fibers
• D. AV bundle

Answer: (A)

In coordinating heartbeats, the impulse travels from the atria to the ventricles and must pause briefly to let the atria finish contracting and filling the ventricles. This pause is provided by the atrioventricular (AV) node, which sits at the junction of the atria and ventricles and slows conduction due to its tissue properties. The slower spread through the AV node gives enough time for ventricular filling before the ventricles are activated. After this delay, the impulse moves quickly through the AV bundle and Purkinje fibers to depolarize the ventricles in a synchronized manner. The SA node sets the pace but does not create this delay, and the Purkinje fibers along with the AV bundle conduct rapidly, so they don’t introduce the pause.

In coordinating heartbeats, the impulse travels from the atria to the ventricles and must pause briefly to let the atria finish contracting and filling the ventricles. This pause is provided by the atrioventricular (AV) node, which sits at the junction of the atria and ventricles and slows conduction due to its tissue properties. The slower spread through the AV node gives enough time for ventricular filling before the ventricles are activated. After this delay, the impulse moves quickly through the AV bundle and Purkinje fibers to depolarize the ventricles in a synchronized manner. The SA node sets the pace but does not create this delay, and the Purkinje fibers along with the AV bundle conduct rapidly, so they don’t introduce the pause.