What are the dangers of smoking for men?

　　harmful substances in smoke

　　Smoking hazards healthy It is a well-known fact. . Different cigarettes release different chemicals when they are lit, but the main chemicals are tar and carbon monoxide. Substances harmful to the human body produced after cigarettes are lit are roughly divided into six categories:

　　(1) Aldehydes, nitrogen compounds, and alkenes are irritating to the respiratory tract.

　　(2) Nicotine, which can stimulate sympathetic nerve , causing damage to the intima of blood vessels.

　　(3) Amines, cyanides and heavy metals are all toxic substances.

　　(4) Phenylpyrene, arsenic, cadmium, methylhydrazine, aminophenol, and other radioactive substances. These substances are carcinogenic.

　　(5) Phenolic compounds and formaldehyde, etc., these substances have the effect of accelerating canceration.

　　(6) Carbon monoxide can reduce the ability of red blood cells to transport oxygen throughout the body.

　　1. Carcinogenesis

　　It has been recognized that smoking causes cancer. Epidemiological surveys show that smoking is one of the important causative factors of lung cancer, especially squamous cell carcinoma and small cell undifferentiated carcinoma. The risk of lung cancer for smokers is 13 times that of non-smokers. If you smoke more than 35 cigarettes a day, the risk is 45 times higher than that of non-smokers. The lung cancer mortality rate among smokers is 10 to 13 times higher than among non-smokers. About 85% of lung cancer deaths are caused by smoking. Smokers who are exposed to chemical carcinogens (such as asbestos, nickel, uranium and arsenic, etc.) are at a higher risk of developing lung cancer. The polycyclic aromatic hydrocarbons in tobacco leaf smoke need to be metabolized by polycyclic aromatic hydrocarbon hydroxylase to have cytotoxic and mutagenic effects. The concentration of hydroxylase in smokers is higher than that in non-smokers. Smoking can reduce the activity of natural killer cells, thereby weakening the body's monitoring, killing and clearing functions of tumor cell growth. This further explains why smoking is a variety of cancer high-risk factors. The incidence of laryngeal cancer in smokers is more than ten times higher than that in non-smokers. The incidence of bladder cancer increases threefold, which may be related to beta-naphthylamine in smoke. In addition, smoking is associated with lip cancer, tongue cancer, oral cancer, esophageal cancer, stomach cancer , colon cancer, pancreatic cancer, kidney cancer and cervical cancer occurrence has a certain relationship. clinical Research and animal experiments show that carcinogens in smoke can also pass through the placenta and affect fetus , resulting in a significant increase in the incidence of cancer in their offspring.

　　2. Effects on the heart and cerebral blood vessels

　　Many studies believe that smoking causes many cardiovascular and cerebrovascular diseases disease The main risk factors for smokers coronary heart disease , hypertension, cerebrovascular disease and peripheral vascular disease have increased significantly. Statistics show that 75% of patients with coronary heart disease and hypertension have a history of smoking. The incidence rate of coronary heart disease in smokers is 3.5 times higher than that in non-smokers. The mortality rate of coronary heart disease in smokers is 6 times higher in smokers than in non-smokers. The incidence rate of myocardial infarction in smokers is 2 to 6 times higher in smokers. Pathological anatomy also found that coronary atherosclerotic lesions are more extensive and severe in the former than in the latter. People with high blood pressure, high cholesterol and smoking increase the incidence of coronary heart disease by 9 to 12 times. 30% to 40% of cardiovascular disease deaths are caused by smoking, and the increase in mortality is proportional to the amount of smoking. Nicotine and carbon monoxide in smoke are recognized as the main harmful factors causing coronary atherosclerosis, but their exact mechanisms are not yet fully understood. Most scholars believe that changes in blood lipids, platelet function and abnormal blood rheology play an important role. High-density lipoprotein cholesterol (HDL-C) can stimulate the production of prostacyclin (PGI2) in vascular endothelial cells. PGI2 is the most effective substance that dilates blood vessels and inhibits platelet aggregation. Smoking can damage vascular endothelial cells, cause a decrease in serum HDL-C, increase cholesterol, and decrease PGI2 levels, thereby causing contraction of peripheral blood vessels and coronary arteries, thickening of the wall, narrowing of the lumen, and slowing of blood flow, resulting in myocardial hypoxia. Nicotine can also promote platelet aggregation. Carbon monoxide in smoke combines with hemoglobin to form carboxyhemoglobin, which affects the oxygen-carrying capacity of red blood cells, causing tissue hypoxia, thereby inducing coronary artery spasm. Due to tissue hypoxia, compensatory polycythemia occurs and blood viscosity increases. In addition, smoking can increase plasma fibrinogen levels and lead to coagulation system dysfunction. ； Smoking can also affect the metabolism of arachidonic acid, reducing the production of PGI2 and relatively increasing thromboxane A2, thereby constricting blood vessels and increasing platelet aggregation. All of the above may promote the occurrence and development of coronary heart disease. Due to myocardial hypoxia, myocardial stress increases and ventricular fibrillation threshold decreases. Therefore, smokers with coronary heart disease are more likely to develop arrhythmias and have an increased risk of sudden death.