Which statement about breathing rate at high altitude is true?

• A. Decreases
• B. Increases
• C. Remains unchanged
• D. Becomes irregular

Answer: (B)

When you go to high altitude, the air has less oxygen, so the body boosts ventilation to take in more oxygen. The drive to breathe is increased by chemoreceptors that detect lower arterial O2 and changes in CO2, causing the breathing rate to rise—this rapid, increased breathing helps raise the amount of O2 entering the lungs and reaching tissues. Over time, the body may compensate for the resulting alkalosis, but the immediate and typical response is an increased breathing rate. Decreasing the rate wouldn’t help with the hypoxia, remaining unchanged wouldn’t meet the body’s increased demand, and becoming irregular isn’t the usual response to this condition.