Atria

Atria are the two upper chambers of the heart responsible for receiving blood returning from the body and lungs. The right atrium collects oxygen-poor blood from the body and sends it to the right ventricle, which then pumps it to the lungs for oxygen. The left atrium receives oxygen-rich blood from the lungs and passes it to the left ventricle, which distributes it to the rest of the body. The atria play a crucial role in maintaining efficient blood flow and cardiac function, acting as initial receivers before blood is pumped into the ventricles for circulation.