The respiratory centre of the brain controls the respiratory muscles. Which of the following does NOT happen? A. An increase in carbon dioxide blood concentration stimulates peripheral chemoreceptors to signal the respiratory centre. B. A decrease in blood pH stimulates peripheral chemoreceptors to signal the respiratory centre. C. Hydronium ions cross the blood-brain barrier to directly stimulate the cen- tral chemoreceptors of the respiratory centre. D. A decrease in oxygen blood concentration stimulates peripheral chemore- ceptors to signal the respiratory centre.
Option C. Hydronium ions cross the blood-brain barrier to directly stimulate the cen- tral chemoreceptors of the respiratory centre does not happen because hydronium ions does not cross the blood brain barrier.
