A Level Biology Practice Exam

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What is the function of the atrio-ventricular node (AVN) in the heart?

To initiate the heartbeat from the ventricles
To control the heart rate during exercise
To stimulate the ventricles to contract after imposing a slight delay to ensure atrial contraction is complete
To regulate blood pressure

The correct answer is: To stimulate the ventricles to contract after imposing a slight delay to ensure atrial contraction is complete

The atrio-ventricular node (AVN) serves a crucial role in the electrical conduction system of the heart. Its primary function is to act as a gatekeeper between the atria and the ventricles. After the electrical impulse is generated by the sinoatrial node (SA node) located in the right atrium, it travels through the atrial walls and reaches the AVN. The AVN imposes a slight delay on this electrical signal. This delay is essential because it allows time for the atria to fully contract and pump blood into the ventricles, ensuring that the ventricles are filled with sufficient blood before they contract. Following this brief pause, the AVN sends the signal down to the ventricles via the bundle of His and Purkinje fibers, facilitating coordinated and effective ventricular contraction. This function is vital for maintaining an efficient heart rhythm and ensuring that the heart effectively pumps blood throughout the body, highlighting the importance of the AVN in coordinating the timing of heart contractions.