Which statement best describes pulmonary circulation?

• A. It carries deoxygenated blood to the lungs and returns oxygenated blood to the heart.
• B. It carries oxygenated blood to the lungs.
• C. It supplies the brain with blood.
• D. It carries blood from the body back to the heart.

Answer: (A)

Pulmonary circulation moves blood between the heart and lungs to enable gas exchange. Deoxygenated blood is pumped from the right ventricle to the lungs via the pulmonary arteries, where it picks up oxygen, and then returns to the heart through the pulmonary veins into the left atrium (and onward to the left ventricle to be circulated to the body). This describes the pathway and gas-exchange purpose of pulmonary circulation, so the statement is correct. The lungs receive blood that is low in oxygen from the right side of the heart, not oxygenated blood, and other options refer to brain circulation or systemic venous return rather than the lung-to-heart loop.