Final answer:
Central chemoreceptors in the brain detect changes in hydrogen ion concentrations in the CSF which reflect changes in the CO2 levels. These receptors regulate the respiratory rate by signaling the respiratory centers in the brainstem to increase respiration when CO2 levels rise, and thus help maintain pH balance in the body.
Step-by-step explanation:
Central chemoreceptors detect changes in the cerebral spinal fluid (CSF) hydrogen ion concentration, which is indeed directly linked to the partial pressure of carbon dioxide (CO2) in the brain. The primary function of these chemoreceptors is to regulate respiration through the medulla oblongata and pons, which are not as sensitive to oxygen concentrations as they are to the concentration of carbon dioxide in the blood.
Hydrogen ions in the CSF can increase due to the presence of higher CO2 levels, resulting in a lower pH (more acidic conditions). As CO2 diffuses across the blood-brain barrier into the extracellular fluid, it converts to carbonic acid, which then dissociates into hydrogen ions and bicarbonate. This increase in hydrogen ions triggers the central chemoreceptors to stimulate the respiratory centers, leading to an increase in the rate and depth of respiration. Consequently, this mechanism ensures the maintenance of a stable internal environment by facilitating the removal of excess CO2, and thereby reducing hydrogen ion concentration in the blood.
Aside from central chemoreceptors, peripheral chemoreceptors located in the carotid arteries and aortic arch also contribute to the respiratory control by sensing systemic arterial concentrations of hydrogen ions. They prompt an increase in ventilation when high levels of hydrogen ions are detected, effectively reducing CO2 levels and increasing systemic pH, thereby maintaining homeostasis.