Which vessels form the hepatic portal vein and what is its function?

• A. Formed by union of inferior mesenteric and superior mesenteric veins; delivers oxygen-rich blood to the heart
• B. Formed by union of superior mesenteric and splenic veins; delivers nutrient-rich blood to the liver for processing
• C. Hepatic arteries; supplies oxygenated blood to the liver
• D. Formed by union of splenic and inferior mesenteric veins; transports bile to the gallbladder

Answer: (B)

The essential idea is how blood reaches the liver and what it carries. The hepatic portal vein is formed by the union of the superior mesenteric vein and the splenic vein, with the inferior mesenteric vein usually feeding into one of these upstream vessels. This vein carries nutrient-rich blood from the digestive organs (and spleen) to the liver so it can be processed, stored, or detoxified before entering the general circulation.

This is different from the hepatic artery, which brings oxygenated blood directly to the liver tissue to meet its metabolic needs. And bile is transported through the biliary ducts, not through the portal vein. So the description that matches the formation by the superior mesenteric and splenic veins and the delivery of nutrient-rich blood to the liver for processing is the most accurate.