The blood in the hepatic portal vein is rich in nutrients and other substances absorbed by the digestive tract. As blood percolates slowly through the sinusoids of the liver, the liver processes the nutrient-rich blood in various ways. The processed blood can then move to the heart, which pumps the nutrient-rich blood to the body to provide nutrients to body cells. The hepatic portal vein is one example of a portal system. Portal systems are venous systems in which blood moves from capillaries to veins to capillaries and then back to veins.
Fetal circulation differs from adult circulation.
The fetus receives its nutrients and oxygen from the mother's blood and the fetus eliminates its carbon dioxide and nitrogenous wastes into the mother's blood. Wastes from the fetal blood move out of the fetal chorionic villi capillaries into the mother's blood in the sinuses of the decidua basalis. Nutrients and oxygen move from the maternal blood into the fetal capillaries of the placenta. The fetal and maternal blood normally do not mix. Since what the mother eats, drinks, breathes, and injects into her bloodstream can be passed on to the child, it is obviously important that the mother eat a good diet and refrain from drinking alcohol, smoking cigarettes, and using drugs during pregnancy.