What are the right and left atria primarily known as?

The right and left atria are primarily known as receiving chambers of the heart. This term is appropriate because the atria function to receive blood returning from the body and lungs before it is sent to the ventricles. The right atrium receives deoxygenated blood from the systemic circulation via the superior and inferior vena cavae, while the left atrium receives oxygenated blood from the pulmonary circulation through the pulmonary veins.

In this role, the atria act as reservoirs, accommodating the blood briefly before it is pushed into the pumping chambers, which are the ventricles. Understanding this structure is critical when studying the heart's overall function and the flow of blood through the cardiovascular system.