Why is smoking cigarette injurious to health?

Explanation

Smoking also paves the way to hard drugs. Smoking Cigarette mostly consist of tobacco, which has been used by human beings for more than 400 years.
Tobacco is also chewed and used as a snuff.
Tobacco contains a large number of chemical substances including nicotine, an alkaloid.
Nicotine stimulates adrenal gland to release adrenaline and nor adrenaline into blood circulation, both of which increases blood pressure and increase heart rate.
Smoking causes increased incidences of cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease, gastric ulcers, etc.
Smoking increases carbon monoxide content in blood and reduces the concentration of haem bound oxygen, which causes oxygen deficiency in body.
Tobacco chewing is associated with increased risk of cancer of the oral cavity.