Hyperventilation and acid–base balance
A person having a panic attack breathes rapidly and deeply. What happens to blood PCO2 and pH?
Answer D: explanation for every choice
A
Respiratory acidosis results from hypoventilation.
B
Lower CO2 raises pH, not lowers it.
C
Higher CO2 lowers pH.
D
Correct. Breathing off CO2 shifts CO2 + H2O ⇌ H+ + HCO3− to the left, lowering H+.
TakeawayBlow off CO2 → alkalosis. Retain CO2 → acidosis.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb144.