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Pharmacology => Drug => Nicotine
Nicotine
Nicotine, an oily liquid substance found in tobacco leaves that acts as a stimulant and also contributes to smoking addiction. When extracted from the leaves, nicotine is colorless, but quickly turns brown when exposed to air. It has an acrid, burning taste. Nicotine is a very powerful poison, and it forms the base of many insecticides.
Cigarette tobacco contains only a small amount of nicotine and most of this nicotine is destroyed by the heat of burning so that the actual concentration of nicotine in smoke is low. However, even a small amount of nicotine is sufficient to be addictive. The amount of nicotine absorbed by the body from inhaling smoke depends on many factors including the type of tobacco, whether the smoke is inhaled, and whether a filter is used.
Tobacco smokers absorb small amounts of nicotine by inhaling smoke from cigars, cigarettes, or pipes. Nicotine is drawn into the lungs where it enters the bloodstream and is pumped by the heart to the brain. It takes only seven seconds for nicotine to enter the brain after being inhaled.
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. Stopping smoking produces withdrawal symptoms within 24 to 48 hours, which commonly include irritability, headaches, and anxiety, in addition to the strong desire to smoke.
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