Describe the structure and function of the hepatic portal system.

• A. Portal veins collect nutrient-rich blood from GI organs and deliver to liver sinusoids for processing; hepatic veins drain liver into the inferior vena cava.
• B. Hepatic arteries supply oxygen to the liver; hepatic veins drain to the portal vein.
• C. Lymphatic vessels drain liver; hepatic ducts drain to gallbladder.
• D. The portal system carries bile from liver to duodenum.

Answer: (A)

The hepatic portal system is a two-capillary-bed circuit that brings blood from the digestive organs to the liver for processing before returning to the heart. Blood from the GI tract drains into the portal vein, which carries nutrient-rich blood to the liver sinusoids. In these liver sinusoids, hepatocytes metabolize nutrients, detoxify substances, and synthesize essential plasma proteins. After this processing, the blood leaves the liver through hepatic veins and drains into the inferior vena cava. This arrangement allows the liver to modify substances absorbed from the gut before they reach systemic circulation.

Other options mix components that aren’t part of the portal blood flow. For example, the hepatic artery supplies oxygenated blood to the liver, and the hepatic veins, not the portal vein, drain the liver into the IVC. Bile ducts and lymphatics are separate pathways and are not how the portal system transports nutrient-rich blood.