Explanation

A-Adrenal gland, B-Adrenaline, C-Nor-adrenaline, D-Blood pressure, E-Heart rate. 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 raise blood pressure and increase heart rate. Smoking is associated with increased incidence of cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart diseases, gastric ulcer, etc.