What is the function of the atrium in the heart?

The atrium serves a critical role in the heart's function by acting as a chamber that receives blood and subsequently forces it into a ventricle. Each side of the heart has its own atrium—specifically, the right atrium receives deoxygenated blood from the body through the superior and inferior vena cavae, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins. After filling with blood, the atria contract to push this blood into the corresponding ventricles: the right atrium into the right ventricle, which then pumps blood to the lungs, and the left atrium into the left ventricle, which pumps blood to the rest of the body.

This function is crucial for maintaining effective circulation and ensuring that the blood is directed appropriately, thus supporting the overall efficiency of the cardiovascular system. Understanding the atrium's role provides insight into heart anatomy and the rhythm of blood flow through the body.