What does the AV node do in cardiac function?

The atrioventricular (AV) node plays a crucial role in the heart's electrical conduction system. Its primary function is to relay electrical impulses from the atria to the ventricles, ensuring that the heart chambers contract in a coordinated manner. When the sinoatrial (SA) node fires an electrical signal, it first stimulates the atria to contract and fill the ventricles with blood. The signal then travels to the AV node, which momentarily delays its transmission to the ventricles. This pause allows the ventricles sufficient time to fill before they contract, creating an efficient pumping action.

Understanding this function is vital for grasping how normal heart rhythm works and how dysregulation can lead to arrhythmias or other cardiac conditions. The other choices do not accurately describe the direct role of the AV node: regulating blood flow involves a broader systemic function that includes vascular health and responsiveness, stimulating heart muscle contraction is primarily the role of pacemaker cells and their impulses, and coordinating heart valve function relates to the mechanical aspects of blood flow rather than electrical signaling.