Read the following passage and answer the question that follow :
The data below shows the concentration of nicotine smoked by a smoker taking 10 puffs/minute.
[Graph: "Smoking Cigarette", concentration of nicotine in blood (mg/cm3) against time (minutes), 1 to 15. The line rises steadily from about 0 at 1 minute to a peak of 45 at 10 minutes, falls sharply to 20 at 11 minutes, then declines slowly to about 10 at 15 minutes.]
(b) How does cigarette smoking result in high blood pressure and increase in heart rate ?
Show Hint
Nicotine releases adrenaline and noradrenaline, which raise heart rate and blood pressure.
Step 1: Name the active agent:
Nicotine is the stimulant present in tobacco smoke. It acts on the nervous system and on the adrenal glands.
Step 2: Hormone release:
Nicotine stimulates the adrenal gland to release adrenaline and noradrenaline into the blood.
Step 3: Effect on heart and vessels:
These hormones make the heart beat faster, so the heart rate increases.
They also narrow (constrict) the blood vessels, which raises the resistance to blood flow.
Faster pumping and narrow vessels together raise the blood pressure.
Final Answer:
Nicotine makes the adrenal gland release adrenaline and noradrenaline, which raise heart rate and constrict vessels, so blood pressure rises.
