Which heart chamber receives oxygenated blood from the lungs, and which chamber pumps it to the body?

• A. Right atrium; right ventricle
• B. Left atrium; left ventricle
• C. Right ventricle; left atrium
• D. Left ventricle; right atrium

Answer: (B)

Oxygenated blood from the lungs returns to the heart into the left atrium, and it is then pumped to the body by the left ventricle. Pulmonary veins bring the oxygen-rich blood into the left atrium, which passes it to the left ventricle through the mitral valve. When the left ventricle contracts, it sends blood out through the aorta to supply the body's tissues. This contrast with the right side, which handles deoxygenated blood returning from the body and sends it to the lungs.