The main function of the liver is: (1) to participate in the metabolism of diseases, sugar and fat in protein; the liver is an important organ of the three major metabolism. It ingests amino acids produced by digestion, absorption and in vivo catabolism to synthesize protein. All plasma albumin and some α and β globulins are synthesized in the liver. Liver can also convert non-amino acid substances into protein, which plays an important role in maintaining protein metabolic balance. Abnormal liver function can cause the decrease of plasma albumin concentration and the change of protein composition ratio. Sugar is an important substance for human energy supply, and the liver can decompose and synthesize glycogen and gluconeogenesis (transforming non-sugar substances into sugar). When blood sugar rises after meals, the liver can quickly synthesize glucose into glycogen for storage. When hungry, liver glycogen can be decomposed into glucose, which is input into blood circulation for tissue needs. Therefore, under the regulation of nerve and endocrine factors, the liver plays a role in maintaining blood sugar stability. Impaired liver function may lead to impaired glucose tolerance. In fat metabolism, bile secreted by the liver contributes to the digestion and absorption of fat. At the same time, the liver is the hub of lipid synthesis, storage, decomposition and operation. The liver synthesizes cholesterol, cholesterol esters, phospholipids, endogenous triglycerides and apolipoprotein, and it is also the only place to decompose cholesterol. Cholesterol is excreted by bile after decomposition. Liver cell damage can reduce plasma cholesterol; Biliary tract obstruction, elevated plasma cholesterol. (2) Bilirubin metabolism: Liver cells have the function of absorbing unbound bilirubin from plasma, combining with glucuronic acid in liver cells to form bound bilirubin and discharging it from biliary tract. When liver cells are damaged or bile duct is blocked, bilirubin content in blood increases and jaundice appears. Bilirubin and its metabolites in blood, urine and feces can be used as detection indicators. (3) Bile acid metabolism: Cholesterol first forms primary bile acid in the liver, and then further becomes conjugated cholic acid, which is absorbed by the small intestine and returns to the liver after being discharged into the intestine, forming intestinal-hepatic circulation. Therefore, the liver is closely related to bile acid metabolism. Liver disease can increase the concentration of bile acids in the blood. (4) Biotransformation and excretion function: The liver can detoxify some endogenous or exogenous substances, such as various metabolites, foreign bodies, various drugs or poisons, so that they can be easily excreted with bile or urine. There are many substances excreted by the liver, such as cholesterol, bile acid, alkaline phosphatase and other normal components and some detoxification products. When the excretion function of the liver is impaired, the body may be poisoned by the accumulation of drugs or poisons. (5) Coagulation function: Most coagulation and fibrinolysis factors are made in the liver. Therefore, the liver is very important for maintaining the balance between coagulation and anticoagulation systems. Liver disease may be prone to bleeding due to lack of coagulation factors. The function of the liver is very complicated. In addition to the above, it also plays an important role in vitamin metabolism, hormone metabolism, water-electrolyte balance regulation, immunity and so on.

-For reference.