Question

After arriving at high altitude, humans hyperventilate to maintain PO2. In this case, blood pH would

Select one:

a. Decrease

b. Increase

c. Normal

Answer 1

Increase the PH (Alkalosis)

At high altitude, the partial pressure of oxygen is lower and people have to breathe more rapidly (hyperventilate) to get adequate oxygen. When this happens, the partial pressure of CO2 in the lungs (pCO2) decreases (is "blown off"), causing a respiratory alkalosis.

This would normally be compensated by the kidney excreting bicarbonate and causing compensatory metabolic acidosis (H+ will go up), but this mechanism takes several days. A more immediate treatment is carbonic anhydrase inhibitors which prevent bicarbonate uptake in the kidney and help correct the alkalosis