Water-soluble nutrients stored in blood are routed directly from the small intestine through the portal vein to the liver before any other organ. The portal vein or hepatic portal vein is a blood vessel which carries blood from the GI tract, to the liver. The blood contains nutrients and toxins extracted from digested contents. The portal vein is not a true vein, since it conducts blood to capillary beds in the liver and not directly to the heart. It is the main component of the hepatic portal system.
