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.]
(a) (ii) How will this affect the concentration of carbon monoxide and haem-bound oxygen at 10 minutes ?
Show Hint
Carbon monoxide binds haemoglobin more strongly than oxygen, so CO rises and haem-bound oxygen falls.
Step 1: Know what cigarette smoke carries:
Cigarette smoke contains nicotine and also carbon monoxide (\(\mathrm{CO}\)).
At 10 minutes the smoker has been inhaling smoke continuously, so the nicotine peak also marks heavy smoke intake.
Step 2: Effect on carbon monoxide:
\(\mathrm{CO}\) enters the blood and binds to haemoglobin to form carboxyhaemoglobin.
Its affinity for haemoglobin is about 200 to 250 times higher than that of oxygen.
So the concentration of \(\mathrm{CO}\) in the blood will be high (increased) at 10 minutes.
Step 3: Effect on haem-bound oxygen:
\(\mathrm{CO}\) occupies the haem sites that oxygen would use.
So less \(\mathrm{O_2}\) binds to haemoglobin and the haem-bound oxygen will be low (decreased).
The oxygen carrying capacity of blood falls and the tissues may suffer oxygen shortage.
Final Answer:
At 10 minutes carbon monoxide in the blood is increased and haem-bound oxygen is decreased.
