What is the function of the sinus node in the heart?

The sinus node, often referred to as the sinoatrial (SA) node, serves the critical function of generating electrical impulses that initiate heartbeats. It is located in the right atrium of the heart and is known as the primary pacemaker. This electrical activity determines the heart rate and rhythm by sending out regular impulses that stimulate the heart muscle to contract. The sinus node's impulses spread through the atria, causing them to contract and push blood into the ventricles, and subsequently reach the atrioventricular (AV) node, which then helps relay the impulses to the ventricles. This orchestrated process ensures the heart beats in a coordinated manner, effectively pumping blood throughout the body.

Other options, such as transporting oxygen-rich blood, filtering impurities from the blood, and regulating blood pressure, are vital physiological functions performed by different parts of the circulatory system rather than by the sinus node.