What is the role of the sinoatrial (SA) node?

The sinoatrial (SA) node serves as the primary pacemaker of the heart by generating electrical impulses that initiate each heartbeat. Located in the right atrium, the SA node is responsible for setting the rhythm and rate of the heartbeat, which is crucial for maintaining a coordinated contraction of the heart muscle. This node automatically sends out signals that stimulate the atria to contract, pushing blood into the ventricles.

Because of its role, the SA node ensures that the heart beats in a synchronized manner, coordinating the timing between the contraction of the atria and the ventricles. This is central to normal cardiac function, as it regulates the heart rate based on the body’s demands. The other choices refer to functions either outside the main role of the SA node or describe aspects of cardiac conduction that occur after the SA node initiates the electrical impulses.