Breathing and Exchange of Gases Question 20

20. When you hold your breath, which of the following gas changes in blood would first lead to the urge to breathe?

[2015 RS]

(a) rising $CO_2$ concentration

(b) falling $CO_2$ concentration

(c) rising $CO_2$ and falling $O_2$ concentration

(d) falling $O_2$ concentration

Show Answer

Answer : a

Hints & Solution

(a) Chemoreceptors in the medulla get stimulated by increase in $CO_2$ concentration in the blood of arteries. Decrease in $O_2$ concentration has no significant effect on chemoreceptors.



NCERT Chapter Video Solution

Dual Pane