CHEMICAL REGULATION OF VENTILATION (continued)

C. Hydrogen Ion

1. Response as a function of pH

a. appreciable effect
b. especially marked at acid pH

2. Afferent endings

a. carotid body and aortic body H⁺ sensitive receptors (rapid response)
b. CNS medullary H⁺ receptors (slow H⁺ leakage across the blood-brain barrier, so slow response)

3. Stimulus: pH_a (and pH_CSF)

4. Regulation schematic

CO₂ + H₂O <=> H₂CO₃ <=> H⁺ + HCO₃^-

5. Physiological significance

Contributes to maintaining blood pH in the normal range through control of respiratory ventilation (respiratory compensation)