Which vessel carries oxygenated blood from the lungs to the heart's left atrium?

• A. Vena Cava
• B. Aorta
• C. Pulmonary Vein
• D. Pulmonary Artery

Answer: (C)

Oxygenated blood returns from the lungs to the heart through the pulmonary veins. After gas exchange in the lungs, blood rich in oxygen travels via these veins into the left atrium, then moves to the left ventricle to be pumped out to the body. The pulmonary veins are unique because veins usually carry deoxygenated blood, but in the pulmonary circuit they carry oxygenated blood back to the heart. The other vessels do not fit this path: the vena cava brings deoxygenated blood from the body to the right atrium, the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs, and the aorta carries oxygenated blood from the left ventricle to the systemic circulation.