What are the upper chambers of the heart called?

The upper chambers of the heart are known as the atria. There are two atria: the left atrium and the right atrium. These chambers play a crucial role in the cardiac cycle by receiving blood returning to the heart from the body and lungs before it is pumped into the lower chambers, called the ventricles. The left atrium receives oxygen-rich blood from the lungs via the pulmonary veins, while the right atrium receives deoxygenated blood from the body through the superior and inferior vena cavae. This structure is essential for maintaining efficient circulation and ensuring that oxygenated blood is delivered to the body's tissues. Understanding the roles of the atria helps in recognizing the overall function of the heart in the circulatory system.