The hepatic portal system refers to a venous system that basically transports blood from various parts of the gastro-intestinal tract to the liver. Blood that is supposedly going back to the heart passes through the gastro-intestinal area, then to the liver through this venous system, and then finally to the heart. This venous system is considered very important in some many ways.
One important function of the hepatic portal system is its role in metabolizing various substances through the liver before they are absorbed by the body. In the case of drugs for example, before they are absorbed by the gastro-intestinal tract for general circulation, they must pass through the hepatic portal system first and undergo processing in the liver. In this case, the liver serves as some form of filtering system for various substances before they are released to be absorbed by the body and circulated to other parts including the heart. This substance-filtration and processing can only take place with an efficient hepatic portal system.
The hepatic portal system also plays an important role in terms of the processing of glucose, which is the main source of energy for the various cells in the body. Whenever there is excess glucose, it will be absorbed by various parts of the GIT and later absorbed by hepatic cells that are part of the hepatic portal system. These cells are the ones responsible for converting glucose to glycogen which become stored energy. In situations where in all glucose or energy are already used up by the body, the glycogen stores created through the hepatic portal system will then be activated to become the backup source of energy. Without the absorption of glucose through the hepatic portal system, any excess of this food and energy source will be put to waste as they will not be converted to glycogen or stored energy.