Which vessel drains blood from the gallbladder, pancreas, spleen, and GI tract into the liver?

• A. Main portal vein
• B. Splenic vein
• C. Hepatic artery
• D. Inferior vena cava

Answer: (A)

The essential idea is the hepatic portal venous system, which delivers nutrient-rich blood from abdominal organs to the liver for processing. Blood from the gallbladder, pancreas, spleen, and GI tract drains into the portal vein, which carries it to the liver. The portal vein is formed by the union of the splenic vein and the superior mesenteric vein behind the pancreas and travels to the liver, bringing with it blood from these organs. The hepatic artery provides oxygenated arterial supply to the liver, not a drainage path from these organs, and the inferior vena cava returns systemic venous blood to the heart, not portal blood. So, the vessel that carries blood from those regions into the liver is the main portal vein.