What type of chambers are the right and left atria in the heart?

The right and left atria are referred to as receiving chambers because their primary function is to receive blood returning to the heart from the body and lungs. Specifically, the right atrium receives deoxygenated blood from the systemic circulation through the superior and inferior vena cavae, while the left atrium receives oxygenated blood from the pulmonary circulation via the pulmonary veins.

The design of the atria, with thinner walls compared to the ventricles, reflects their role in collecting blood rather than pumping it. They act as reservoirs that temporarily hold blood before it moves into the more muscular ventricles, which are responsible for pumping blood to the lungs and the rest of the body. This distinction in function is critical in understanding the flow of blood through the heart and the anatomy of its chambers.