Name the toxic substance present in tobacco smoke. Discuss its ill effects on our body.

Explanation

Effect of Tobacco Ingredients.
1. Carbon Monoxide. Tobacco smoke has 2-6% carbon monoxide. The inhaled concentration is 400 ppm. The gas combines with haemoglobin and forms an irreversible complex called carboxyhaemoglobin (COHb). Depending upon the intensity of smoking, carboxyhaemoglobin content of blood may be 2-15 %. It impairs oxygen transport, central nervous system function and induces synthesis of more RBCs.

2. Nicotine. It is colourless or yellowish oily liquid alkaloid which is chemically `C_(10) H_(14) O_(2) (beta`-pyridyl-`alpha`-N-methyl pyrrolidine). Nicotine is the habit forming constituent of tobacco. It has multiple effects due to its absorption in brain, autonomic ganglia and neuromuscular junctions. In brain, nicotine releases dopamine which is stimulant in small amount and depressent hi large amount. Nicotine causes tremors. In higher dose it produces vomiting, convulsions and paralysis. It stimulates as well as depresses respiration, causes concentration of urine, stimulates as well as depresses autonomic ganglia, increases heart beat, serum glucose, cortisol and free fatty acids. There is suppresion of appetite but increase in metabolic rate. Nicotine is used as insecticide because in higher concentration it causes paralysis of skeletal muscles and arrest of respiration.
3. Tar. It is thick viscid dark coloured liquid which gets deposited over the internal surface of respiratory tract. Tar does irritation and cough. Tar is also carcinogenic or cancer causing.
4. Ciliotoxins. They are harmful to cilia present over the lining cells of nasal tract. Cilia are important in pushing out particles from the nasal tract. Ciliotoxins kill cilia and, therefore, prevent cleaning of respiratory passage. Important Ciliotoxins present in tobacco smoke are HCN, formaldehyde, acetaldehyde, acrolein, ammonia and nitrogen oxides. All these ingredients are also irritants. They produce cough and & thickening of lining layer of respiratory passage. Phenol and cresol also cause irritation. They are cocarcinogens which enhance the carcinogenic effect of others. Another cocarcinogen is catechol.
5. Carcinogens. They cause the development of cancer. Tobacco smoke contain a number of carcinogens-hydrazine, nitrosoamines, vinyl chloride, polynuclear aromatic hydrocarbons, benzopyrene, N-nitronornicotine, (3-naphthylamine. Tumour stimulants (indole and carbazole) bring about tumour formation in the tissue where carcinogens have caused division of cells.