Essential to normal bodily functioning, the liver has many different roles in the body, including processing and storing nutrients, detoxifying harmful chemicals from the body, and performing vital digestive functions. Located on the surface of the liver is the porta hepatis. The porta hepatis is a gate, or fissure, where different nerves, vessels, and ducts enter and exit. Veins that run through the liver make up the hepatic portal system, which functions to carry blood from the spleen, stomach, intestines, and pancreas to the liver.
Entering the liver through the porta hepatis is the hepatic portal system. This system is made up of the hepatic portal vein, the hepatic artery, and a network of hepatic nerves. Exiting the liver via the porta hepatis are two hepatic ducts, which remove bile from the liver and lymphatic vessels.
Constituting the hepatic portal system is the hepatic portal vein. This vein is the largest in the system and is created by the uniting of the superior mesenteric vein and the splenic vein. The superior mesenteric vein drains blood from the small intestine and the splenic vein drains blood from the spleen. The splenic vein also receives from the inferior mesenteric vein, which drains blood from part of the large intestine and the pancreatic veins, which drain blood from the pancreas. Before entering the liver, the hepatic portal vein also receives blood from gastric veins.
The function of the hepatic portal system is to carry blood into the liver through the hepatic portal vein from small blood vessels called capillaries located in parts of the abdomen. This vein carries blood from the intestines, pancreas, stomach, and spleen to sinusoids, or dilated capillaries, in the liver. As such, the nutrients that are absorbed from these organs are transported to the liver via the hepatic portal system, where they are stored and processed.
One of the many functions of the liver is storing and processing nutrients. Cells that constitute the liver are called hepatocytes, and these cells help to store nutrients as glycogen, fat, and vitamins by removing sugar from blood. Hepatocytes also assist with the processing of nutrients by changing substances that cannot be used by most cells into more usable substances. The liver is involved in detoxifying the body and achieves this by changing the structures of toxic substances into less-harmful substances, making them easier to eliminate. Bile production in the liver is also important and assists digestive functioning by diluting stomach acids.