Where systemic circulation terminates.

• A. Left atrium
• B. Pulmonary artery
• C. Right atrium
• D. Aorta

Answer: (C)

Systemic circulation terminates where the blood returning from the body reunites with the heart. That venous blood travels through the superior and inferior venae cavae and enters the right atrium. From there it moves to the right ventricle and then into the pulmonary circuit to be re-oxygenated. The left atrium receives oxygenated blood from the lungs, not systemic return; the pulmonary artery is part of the lung circulation, carrying blood away from the heart to the lungs; the aorta distributes arterial blood to the body rather than receiving systemic return.