The right atrium is one of the four chambers of the heart. Its function is to receive deoxygenated blood from the body through the inferior and superior vena cava. The right atrium then pumps this blood to the right ventricle, which pumps it to the lungs through the pulmonary arteries. In the lungs, fresh oxygen enters the bloodstream, and the blood moves to the left side of the heart, where it is then pumped to the rest of the body. The right atrium plays a crucial role in the flow of blood through the heart.