Which vessel returns oxygenated blood from the lungs to the heart?

• A. Aorta
• B. Pulmonary artery
• C. Pulmonary veins
• D. Superior vena cava

Answer: (C)

The flow concept being tested is how oxygenated blood returns to the heart after gas exchange in the lungs. Blood that leaves the lungs through the lungs’ capillaries is rich in oxygen, and it travels back to the heart through the pulmonary veins. These vessels deliver that oxygenated blood into the left atrium, then it moves to the left ventricle and is pumped out to the rest of the body via the aorta.

This vessel is unique because, unlike most veins, it carries oxygenated blood. In contrast, the pulmonary artery carries blood from the heart to the lungs and is deoxygenated, the aorta carries oxygenated blood away from the heart to the body, and the superior vena cava brings deoxygenated blood from the upper body to the heart.