Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
Central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface, are sensitive to the pH of their environment.
These act to detect a change in pH of the cerebral spinal fluid.
An increase in carbon dioxide tension of the arteries will indirectly cause the blood to become more acidic; the cerebral spinal fluid pH is closely comparable to the plasma pH, as carbon dioxide easily diffuses across the blood/brain barrier.
The detection of variation in the arterial carbon dioxide tension acts as a quick-response-system, useful in short term regulation.
This system utilizes a negative feedback system, therefore if the pH of the cerebral spinal fluid does not compare to an ideal “set” level, then the receptor will send an error signal to the effectors and appropriate action may be executed.
- Essentials of Human Physiology by Thomas M. Nosek. Section 4/4ch6/s4ch6_21.
- Overview at cvphysiology.com