Deoxygenated blood from the abdomen, pelvis, and lower extremities returns to the right atrium via the:

• A. Superior vena cava
• B. Inferior vena cava
• C. Pulmonary vein
• D. Aorta

Answer: (B)

Blood returning from the lower body collects into the large vein that travels upward to the heart and delivers it to the right atrium. This vessel, the inferior vena cava, carries deoxygenated blood from the abdomen, pelvis, and lower extremities into the right atrium. From there, the blood moves to the right ventricle and then to the lungs for oxygenation. The other vessels have different roles: the superior vena cava handles upper-body venous return to the right atrium; the pulmonary veins return oxygenated blood from the lungs to the left atrium; and the aorta carries oxygen-rich blood away from the heart to the body.