Cigarette smoking

http://kidshealth.org/kid/watch/house/smoking.html 

 Cigarette Smoking 

 Cigarette smoking is addictive; it fulfills these three criteria:

1. • Smokers develop a tolerance to nicotine (they need to smoke more and more for an effect).
     
   • Smokers become dependent on it (they need it to feel comfortable).
     
   • Smokers suffer withdrawal symptoms (physical and psychological discomfort when they try to stop smoking).
     
2. There are hundreds of chemical substances in cigarette smoke. Three of the most damaging are:
   
   • Tars--damage delicate lung tissue and are considered the main cancer- causing agent in cigarette smoke.
     
   • Nicotine--a poison found only in tobacco leaves. It can be extracted as a colorless, oily transparent liquid and used in solution as an insecticide. One drop of pure nicotine can be fatal to humans.
     (1) It is a powerful stimulant to the brain and central nervous system that 'hits'' the brain within four seconds. Like the drug, alcohol, after it initially stimulates, it has a depressant effect.
     (2) Nicotine constricts (narrows) the blood vessels, cutting down the flow of blood and oxygen throughout your body. Your heart has to pump harder, thus increasing the chance of heart disease. It raises the blood pressure and also narrows bronchioles (air passageways) in the lungs, also depriving the body of some oxygen.
     
   • Carbon monoxide--replaces needed oxygen in your red blood cells. Even after one stops smoking, carbon monoxide stays in the bloodstream for hours, depriving the body of oxygen until the oxygen level in your blood returns to normal. Carbon monoxide is a waste product of cigarette smoking and also of gasoline engines.
     
3. Some of the diseases caused by cigarette smoking are:
   
   • Chronic bronchitis (inflammation of the bronchi which are the breathing tubes in the lungs)
     
   • Laryngitis (inflammation of the throat)
     
   • Emphysema(a degenerative lung disease that destroys breathing capacity)
     
   • Smoking is a contributing factor in cancer of the lungs, mouth, and esophagus.
     
4. Smoking cigarettes stains the teeth, reduces the efficiency of the body's ability to taste and smell, and increases the process of wrinkling of the skin (especially around the eyes).
   
5. The effects of some medication taken by a person may be increased, decreased, or cancelled out by smoking.
   
6. Cigarette smoking by pregnant women may cause harm to the fetus.
   
7. Cigarette smoke pollutes the air in enclosed places, which also affects the nonsmokers present.
   
8. Smoke from an idle cigarette contains at least as much tar and nicotine as inhaled smoke (American Lung Association).
   
9. Chewing tobacco may lead to cancer of the mouth and to an addiction because of the nicotine that is absorbed through the mouth's lining.
   
10. It is generally accepted that "peer pressure" encourages many young people between the ages of 10 and 18 to begin experimenting with smoking (American Cancer Society).
    
11. When a person quits smoking, the body begins to repair some of the damage caused by the cigarette smoking.
    
    
12.