What is the function of the SA node?

The function of the SA node, or sinoatrial node, is to generate the electrical impulses that initiate each heartbeat. This structure is often referred to as the heart's natural pacemaker because it sets the rhythm for the entire cardiac cycle. The SA node is located in the right atrium and is responsible for determining the heart rate by sending signals that cause the heart muscles to contract in a coordinated manner. This impulse travels through the atria, leading to their contraction and subsequently passing to the AV node, which aids in the sequential contraction of the ventricles.

Understanding the role of the SA node is crucial, as it is the starting point for the electrical conduction system of the heart, ensuring effective blood circulation throughout the body. The other options listed do not directly pertain to the primary function of the SA node; rather, they relate to other aspects of cardiac physiology or systemic function.