Which of the following blood vessels carries oxygenated blood into the heart?

Step 1: Analyze the question The question asks which vessel brings oxygenated blood into the heart.

Step 2: Key concept In the mammalian double circulation:

• Pulmonary circulation: the heart sends deoxygenated blood to the lungs, and oxygenated blood returns to the heart.
• Systemic circulation: the heart sends oxygenated blood to the body, and deoxygenated blood returns to the heart.

Arteries usually carry blood away from the heart, and veins carry blood towards it. The pulmonary vessels are the exception to the "arteries carry oxygenated blood" rule.

Step 3: Check each option

• A. Pulmonary artery: carries deoxygenated blood from the right ventricle to the lungs. It leaves the heart, so this is wrong.
• B. Anterior vena cava: carries deoxygenated blood from the head and upper body into the right atrium. This is wrong.
• C. Pulmonary vein: carries oxygenated blood from the lungs into the left atrium. This is correct.
• D. Posterior vena cava: carries deoxygenated blood from the lower body into the right atrium. This is wrong.

Step 4: Answer The pulmonary vein is the only vessel that brings oxygenated blood into the heart (the left atrium).

Exam tip: Remember "Pulmonary is the opposite." The pulmonary artery carries deoxygenated blood and the pulmonary vein carries oxygenated blood. Also, every vena cava carries deoxygenated blood to the right side of the heart.