What is the function of the atrioventricular (AV) node?

The atrioventricular (AV) node plays a critical role in the cardiac conduction system by relaying electrical impulses from the atria to the ventricles. Located between the atria and the ventricles, the AV node serves as a crucial electrical gateway. When the sinoatrial (SA) node fires an electrical impulse, it travels through the atria, leading to their contraction. However, the AV node delays this impulse slightly before transmitting it to the ventricles. This delay is vital as it allows the atria to fully contract and push blood into the ventricles before they begin to contract, ensuring efficient blood flow through the heart and to the rest of the body.

The other options do not accurately describe the primary function of the AV node. Monitoring blood flow in the heart pertains more to the vascular system rather than the electrical conduction system. Reducing heart rate is a function associated with various autonomic responses, not the direct action of the AV node itself. Maintaining oxygen levels in the blood is dependent on respiratory functions and the efficiency of gas exchange in the lungs, rather than the role of the AV node in the heart's electrical system.