Question

Chemosensitive area of the respiratory centre of the brain is affected by

• A. less carbon dioxide and low pH
• B. less oxygen and high pH
• C. excess oxygen and high pH
• D. excess carbon dioxide and low pH

Answer 1

The correct option is D excess carbon dioxide and low pH

The chemosensitive area in the respiratory centre of the brain is very sensitive to changes in blood pH. When there is an increase in carbon dioxide in the blood, it diffuses into the cerebrospinal fluid (CSF) and forms $H^{+}$ ions and ${HCO}_3^{-}$ ions. This increase in $H^{+}$ ions in the CSF decreases the pH, which gets detected by the central chemoreceptors, which then stimulate the inspiratory centre in the brain to increase the respiratory rate.