Question

multiple choice question
the central chemoreceptors respond to ____, not to ____.
o carbon dioxide; hydrogen ions
o hydrogen ions; carbon dioxide
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Explanation:

Central chemoreceptors are located in the brainstem. They respond to changes in hydrogen ions (\(H^+\)) in the cerebrospinal fluid. Carbon dioxide (\(CO_2\)) can cross the blood - brain barrier. When \(CO_2\) enters the cerebrospinal fluid, it reacts with water (\(H_2O\)) to form carbonic acid (\(H_2CO_3\)), which then dissociates into \(H^+\) and bicarbonate ions (\(HCO_3^-\)). The central chemoreceptors detect the change in \(H^+\) (not the \(CO_2\) directly).

Answer:

hydrogen ions; carbon dioxide