Lung cancer in smokers is caused mainly by
Correct answer: A. the carcinogenic chemicals in tar
- A. the carcinogenic chemicals in tar
- B. the heat of the smoke
- C. nicotine acting on the brain
- D. the loss of surfactant from the alveoli
Explanation
Tar contains carcinogens such as benzopyrene that mutate the genes controlling cell division in the bronchial epithelium, and years of exposure eventually produce an uncontrolled tumour. Nicotine is highly addictive but is not itself the main carcinogen, which is why a nicotine patch is far safer than a cigarette. The risk rises with the number of cigarettes and the number of years smoked.
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About Effects of Smoking
Smoking exposes the respiratory system to nicotine, tar and carbon monoxide, damaging cilia, reducing oxygen transport and narrowing or inflaming airways. The topic covers dependence, chronic bronchitis, emphysema, lung cancer and cardiovascular effects, while separating short-term physiological changes from long-term disease.
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