Which part of the heart receives oxygen-poor blood from the body?

The right atrium is responsible for receiving oxygen-poor blood from the body. Blood that has traveled throughout the body and delivered oxygen to the tissues returns to the heart via the superior and inferior vena cavae, which empty into the right atrium.

From the right atrium, blood flows into the right ventricle, which then pumps it to the lungs for oxygenation. This process is part of the pulmonary circulation, where carbon dioxide is exchanged for oxygen in the lungs, enabling the cycle of oxygen-rich and oxygen-poor blood to continue.

In contrast, the left atrium receives oxygen-rich blood from the lungs, which has just been oxygenated. The left ventricle is responsible for pumping this oxygen-rich blood out to the rest of the body. The right ventricle, while it deals with oxygen-poor blood, receives it from the right atrium rather than receiving it directly from the body. Therefore, the right atrium's role as the entry point for deoxygenated blood characterizes why it is the correct answer in this context.