College of Massage Therapists of British Columbia (CMTBC) Practice Exam

What is the role of the AV node in the heart's conduction system?

1. Controls heart rate

2. Delays electrical impulses

3. Initiates heartbeats

4. Controls the contraction of the ventricles

The correct answer is: Delays electrical impulses

The atrioventricular (AV) node plays a critical role in the heart's conduction system by delaying electrical impulses that travel from the atria to the ventricles. This delay is essential because it ensures that the atria have enough time to fully contract and pump blood into the ventricles before the ventricles contract. The timing of this sequence is vital for efficient heart function and maintaining proper blood flow. The AV node serves as a gatekeeper, allowing impulses to pass from the upper chambers of the heart (the atria) to the lower chambers (the ventricles) at a controlled rate. If the impulse were to move too quickly or without a delay, the atria and ventricles would contract almost simultaneously, which could lead to inefficient pumping and reduced cardiac output. While other components of the conduction system, such as the sinoatrial (SA) node, initiate heartbeats, and the bundle branches help coordinate ventricular contractions, the unique functionality of the AV node lies specifically in managing the timing of impulses, thereby playing a crucial role in maintaining the heart’s rhythm and efficiency.