Question

When carbon dioxide concentration in blood increases, breathing becomes ____________.

• A. There is no effect on breathing
• B. Slow and deep
• C. Faster and deeper
• D. Shallower and slow

Answer 1

The correct option is C Faster and deeper

When carbon dioxide concentration in blood increases, breathing becomes faster and deeper, since an increase in the carbon dioxide concentration of the blood decreases the affinity of haemoglobin for oxygen. Thus, there is less oxygen available for the tissues. Hence the body needs to get rid of the excess carbon dioxide as well as take in more oxygen.

As a general rule, the faster and deeper you breathe, the greater is the air exchange happening in your lungs. This means there is an increase in the rate of oxygen uptake by blood and also of carbon dioxide wash-out. So if you breathe fast and deep, that will clear out the maximum amount of carbon dioxide from your blood. Hence a decrease in blood CO2 concentration.

Similarly, if you breathe in slow and deep, it will be less effective in washing-out CO2 from your blood. But this will still be more effective than slow and shallow breathing, because of the same reasons.