Toxic metabolic process in the body 1. Toxic invasion pathway: The speed, intensity and performance of toxic effects on the body are related to the invasion pathway and absorption rate of toxic substances. Usually, toxic substances can enter the body through the digestive tract, respiratory tract or skin mucous membrane and other ways to cause poisoning. (1) Digestive tract: It is a common way of life poisoning, for example, poisonous food, sedative sleeping pills, etc. are often poisoned by oral intake. Toxic substances are rarely absorbed through the oral or esophageal mucosa, cyanide and other substances are less absorbed in the stomach and mainly absorbed by the small intestine. After the action of small intestinal fluid and enzymes, the nature of the toxic substance is partly changed and then enters the blood circulation and is distributed to the tissues and organs of the whole body after detoxification by the liver. (2) Respiratory tract: Because of the large surface area of alveoli and abundant pulmonary capillaries, the poison inhaled through the respiratory tract can rapidly enter the blood circulation and become poisoned, which is 20 times faster than that absorbed into the blood through the digestive tract. Therefore, the patient’s poisoning symptoms are serious and the disease develops quickly. In occupational poisoning, the poison is often inhaled through the respiratory tract in the form of dust, smoke, vapor or gas. A common case of life poisoning is carbon monoxide poisoning. (3) Skin mucous membrane: There is a lipid-like layer on the surface of healthy skin, which can prevent water-soluble poisons from invading the organism. For a few fat-soluble poisons (such as benzene, aniline, nitrobenzene, ether, chloroform or organophosphorus compounds, etc.), the skin loses its barrier role and can be absorbed by the sebaceous glands or mucous membranes. Toxic substances that can damage the skin (such as arsenic compounds, mustard gas, etc.) can also be absorbed through the skin poisoning. In the skin sweating or have damage, can accelerate the absorption of toxins. Some poisons can also be absorbed through the bulbar conjunctiva poisoning. Venomous snake bite, venom can be poisoned through the wound into the blood. 2. Poison metabolism: After the poison is absorbed into the blood, it is combined with certain components of red blood cells or plasma and distributed to tissues and cells throughout the body. Lipid-soluble non-electrolyte toxicants are distributed in large amounts in fat and some neural tissues; non-electrolyte toxicants that are insoluble in lipids have poor ability to penetrate cell membranes. Electrolyte toxicants (such as lead, mercury, manganese, arsenic and fluorine) are unevenly distributed in the body. Toxins are mainly metabolized in the liver by oxidation, reduction, hydrolysis and binding, and then interact with chemicals in tissues and cells to break down or synthesize different compounds. For example, ethanol is oxidized to carbon dioxide and water; ethylene glycol is oxidized to glycolic acid; benzene is oxidized to phenol, etc. Most of the toxins are metabolized to reduce toxicity, which is the detoxification process. A few metabolized toxicity but enhanced, such as the oxidation of parathion for more toxic parathion. 3, the excretion of toxins: most of the toxins entering the body after metabolism and excretion. Toxic excretion rate is related to its solubility in the tissue, volatility, excretion and the functional state of the circulatory organs. The kidney is the main organ of toxic excretion, water-soluble toxins are excreted faster by the kidneys, and the use of diuretics can accelerate the excretion of renal toxins. Heavy metals (such as lead, mercury and manganese) and alkaloids are mainly excreted by the digestive tract; some volatile poisons (such as chloroform, ether, alcohol and hydrogen sulfide, etc.) can be excreted in their original form by the respiratory tract, and the greater the tidal volume, the stronger the role of excreting poisons; some fat-soluble poisons can be excreted by the skin sebaceous glands and mammary glands, and a few poisons are excreted by the skin.