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NEET 2015
Exam
NEET
Year
2015
Subject
Zoology
Chapter
Breathing and Exchange of Gases

NEET 2015 · Zoology · Breathing and Exchange of Gases

When you hold your breath, which of the following gas changes in...

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

Options

  1. AFalling O2{O}_{2} concentration
  2. BRising CO2C{O}_{2} concentration
  3. CFalling CO2C{O}_{2} concentration
  4. DRising CO2C{O}_{2} and falling O2{O}_{2} concentration

Correct answer

B. Rising CO2C{O}_{2} concentration

Step-by-step solution

The rise in CO2C{O}_{2} 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 CO2C{O}_{2} the concentration of blood.
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