In all the parts of the circulation, venous blood passes from the tissues to the heart by the most direct route through only one capillary bed. In the (hepatic) portal circulation of man, venous blood passes from the capillary beds of the abdominal part of the digestive system, the spleen, and pancreas to the liver. It passes through a second capillary bed, the hepatic sinusoids, in the liver before entering the general circulation via the inferior vena cava (IVC). In this way, blood with a high concentration of nutrients, absorbed from the stomach and intestines, goes to the liver first. In the liver, certain modifications take place, including the regulation of nutrient supply to other parts of the body.

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