Patient Care Technician (PCT) AAH Practice Exam

What is the largest vein in the human body that returns blood from below the diaphragm?

1. Superior vena cava

2. Aorta

3. Inferior vena cava

4. Pulmonary vein

The correct answer is: Inferior vena cava

The largest vein in the human body that returns blood from below the diaphragm is the inferior vena cava. This vein plays a critical role in the circulatory system as it carries deoxygenated blood from the lower half of the body back to the right atrium of the heart. The inferior vena cava is formed by the merging of the right and left common iliac veins and ascends along the right side of the vertebral column. It collects blood from several major veins, including the lumbar veins, right and left renal veins, right suprarenal vein, and the right gonadal vein, making it essential for returning blood from the abdominal and pelvic regions. In contrast, the superior vena cava primarily returns blood from the upper part of the body, including the head, neck, arms, and chest. The aorta, on the other hand, is the body's largest artery, responsible for distributing oxygenated blood to the systemic circulation, rather than being a vein that returns blood. The pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart, which is unrelated to returning blood from below the diaphragm. Understanding the role of the inferior vena cava in the circulatory system highlights its importance as the main pathway for returning blood from