The liver is an essential part of the human digestive system. It is an accessory organ of the digestive system that assists with digestive processes without being directly involved with food digestion. The liver assists the digestive system by secreting bile and bile salts to help emulsify fats and aid in their digestion in the small intestine.
The liver is composed of hepatocytes that produce bile, which then passes through the bile ducts in the liver and reaches the gallbladder. The bile is stored in the gallbladder until food enters the digestive system. When foods that are high in fat reach the duodenum, the cells of the duodenum release hormones to signal to the gallbladder to release bile. This, in turn, causes the liver to produce more bile. The bile is released from the gallbladder and emulsifies fats in the small intestine to make them easier to digest.
The liver also performs important protein digestion functions. The hepatocytes in the liver synthesize plasma proteins, break down excess amino acids and convert ammonia into urea. All of these processes break down excess protein and amino acids from the foods that humans eat. The liver also performs many other vital functions, including maintaining blood glucose levels, processing drugs, detoxifying drugs, storing vitamins and minerals and activating vitamin D.