What is the primary function of the atrioventricular valves in the heart?

The primary function of the atrioventricular valves is to prevent blood from flowing back into the atria once the ventricles contract. These valves, which include the tricuspid valve on the right side of the heart and the mitral valve on the left side, open to allow blood to flow from the atria into the ventricles during the heart's filling phase and close tightly during the contraction phase. This closure is crucial in maintaining unidirectional blood flow within the heart, ensuring that oxygenated and deoxygenated blood does not mix and that the pressure within the heart chambers is properly regulated during each cardiac cycle.

The other functions listed, such as allowing ejection of blood into arteries, relate more to the aortic and pulmonary valves located at the exit points of the ventricles. Facilitating gas exchange occurs in the lungs, not within the heart, and controlling heart rhythm is primarily managed by the sinoatrial node and the conduction system of the heart rather than by the atrioventricular valves.