The main chemical drive to breathe
In a healthy person at rest, what is the main chemical stimulus that adjusts breathing rate?
Answer C: explanation for every choice
A
Low O2 drives breathing strongly only when PO2 drops well below normal.
B
Glucose doesn't directly regulate breathing.
C
Correct. CO2 diffuses into the CSF and lowers its pH, which central chemoreceptors in the medulla detect.
D
Blood pressure is regulated by baroreceptors, not breathing chemoreceptors.
TakeawayNormal breathing is driven mainly by CO2, not O2.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb145.