Q. Nicotine stimulates the adrenal gland and increases blood pressure and heart rate.
(a) Despite higher heart rate leading to faster pumping of the blood, why would a
smoker show oxygen deficiency in the body?
(b) Why does a chronic smoker experience withdrawal symptoms if he abruptly
discontinues smoking?
Solution:
a. Nicotine (an alkaloid) causes stimulation of the adrenal gland to release adrenaline and nor-adrenaline into blood circulation. These hormones lead to a rise in blood pressure and heart rate. But at the same time, nicotine also increases the carbon monoxide (CO) content in blood which results in the reduction of the concentration of haem bound oxygen. When haem bound oxygen is less, there occurs oxygen deficiency in the body.
b. When one starts smoking, his/her body becomes dependent on nicotine which is a stimulator for the release of dopamine in the brain. Dopamine gives a pleasurable feeling to that person. And so, when a chronic smoker abruptly discontinues smoking, he experiences withdrawal symptoms.