The liver is the largest substantial gland in the human body and has important and complex functions. The liver has a dual blood supply from the hepatic artery and portal vein, and a hepatic venous and biliary outflow system, together with abundant blood sinusoids and a delicate lobular structure, making the liver not only unique in its anatomy but also in its functions. However, the liver has a very strong compensatory function, and very few functions can be replaced by other organs under certain conditions. The liver can synthesize a variety of plasma proteins (albumin, fibrinogen and prothrombin); it is rich in enzymes related to amino acid metabolism and is an important organ for the synthesis of urea; it maintains the relative stability of blood glucose by synthesizing and decomposing carbohydrates; the process of lipid metabolism is mainly carried out in the liver; it plays an important role in the absorption and storage of vitamins; it also It is closely related to the inactivation and excretion of some hormones. 2. Biological conversion function Most foreign substances (such as various toxic substances, drugs, carcinogens) and biologically active substances and metabolites (hormones, amines, etc.) produced during the metabolic process in the body are metabolized and converted in the liver to inactivate or change the pharmacological properties and to increase their polarity or water solubility, which facilitates their excretion from urine or bile. Certain toxic chemicals, including drugs, are metabolized by the intrahepatic enzyme system to produce more toxic metabolites. 3.Excretory function Mainly refers to the production and excretion of bile acids and bilirubin. Toxic substances and drugs are also excreted from the bile after being taken up and biotransformed by hepatocytes. 4.Immune function The hepatic Kupffer cells are macrophages located in the hepatic sinusoids, which can remove endotoxins, regulate immune and inflammatory responses, and phagocytose and destroy pathogenic microorganisms or decompose and present them to T cells to stimulate specific immune responses.