Which component of the heart is known as the pacemaker?

The sinus node, or SA node, is recognized as the heart's natural pacemaker. It is located in the right atrium and is responsible for initiating the electrical impulses that dictate the heart's rhythm. These impulses then spread through the heart muscle, causing the atria to contract and pump blood into the ventricles. The SA node's intrinsic rate of firing sets the pace of the heartbeat, typically around 60 to 100 beats per minute in a resting state.

Other components of the heart play significant roles in the conduction system, but they do not serve as the primary pacemaker. The atrioventricular (AV) node, for instance, acts as a gatekeeper and helps regulate the impulses between the atria and ventricles, but it is generally not the primary source of electrical activity; it functions primarily if the SA node fails. The ventricles themselves are responsible for the strong contractions that eject blood, but they do not initiate the rhythm. The bicuspid valve (or mitral valve) is involved in preventing backflow between the left atrium and left ventricle, but it has no electrical function. Thus, the SA node's role is crucial in maintaining the heart's pace and rhythm effectively.