smoking - Nicotine, an oily liquid substance found in tobacco leaves that acts as a stimulant and also contributes to smoking addiction. It has an acrid, burning taste. Nicotine is a very powerful poison, and it forms the base of many insecticides.

... SMOKING Nicotine, an oily liquid substance found in tobacco leaves that acts as a stimulant and also contributes to smoking addiction. It has an acrid, burning taste. Nicotine is a very powerful poison, and it forms the base of many insecticides. Nicotine has various effects on the body. In small doses nicotine serves as a nerve stimulant, entering the bloodstream and promoting the flow of adrenaline, a stimulating hormone. It speeds up the heartbeat and may cause it to become irregular. It also raises the blood pressure and reduces the appetite, and it may cause nausea and vomiting. The known health risks associated with cigarette smoking, such as damage to the lungs and lung cancer, are thought to be caused by other components of cigarettes such as tars and other by-products of smoking, and by the irritating effects of smoke on the lung tissue. Addiction to smoking is caused by nicotine itself.

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