Q150 / 180 · NEET 2015 (Phase 1) · Zoology

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

  • A
    Falling O2 concentration
  • Correct answer
    B
    Rising CO2 concentration
  • C
    Falling CO2 concentration
  • D
    Rising CO2 and falling O2 concentration

Solution

The rise in CO2 concentration stimulates chemoreceptors present in the aorta and carotid artery, which stimulates the respiratory centre. The respiratory centre is not directly sensitive to oxygen concentration & hence desire to breathe is induced by rising in CO2 the concentration of blood.

Hence, the correct answer is option: 'B'.

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