[Campbell Biology P.1000] When you hold your breath, which of the following blood gas changes... | Practice Question

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

  • A: Rising O2
  • B: Falling O2
  • C: Rising CO2
  • D: Falling CO2

Explanation

The urge to breathe is primarily triggered by an increase in carbon dioxide CO2 levels in the blood, which leads to a decrease in blood pH. Chemoreceptors detect this change and signal the respiratory control center.