What structure returns blood to the pulmonary arteries?

• A. Coronary veins
• B. Superior vena cava (SVC)
• C. Inferior vena cava (IVC)
• D. Capillary beds

Answer: (B)

The structure responsible for returning blood to the pulmonary arteries is the superior vena cava (SVC). The SVC collects deoxygenated blood from the upper half of the body, including the head, neck, and arms, and transports it back to the right atrium of the heart. From there, this blood enters the right ventricle, which then pumps it into the pulmonary arteries. The pulmonary arteries carry this deoxygenated blood to the lungs for oxygenation.

While the inferior vena cava (IVC) also returns deoxygenated blood, it serves the lower half of the body and similarly transports that blood to the right atrium. The coronary veins return blood from the heart muscle itself to the right atrium but do not directly connect to the pulmonary circulation. Capillary beds are the sites of exchange between blood and tissues, where oxygen is delivered, and carbon dioxide is collected, but they do not return blood to the pulmonary arteries. Thus, the SVC is correctly identified as the structure that facilitates this crucial return of blood prior to its oxygenation in the lungs.