What critical role do central chemoreceptors play in respiratory responses?

• A. Hypercapnia/hypocapnia
• B. Hypoxia
• C. Acidosis/alkalosis
• D. Rebound hyperventilation

Answer: (A)

Central chemoreceptors, located in the medulla oblongata, primarily monitor changes in the composition of blood, particularly the levels of carbon dioxide (CO2) and pH. When CO2 levels rise in the blood (hypercapnia), it leads to an increase in hydrogen ion concentration, resulting in acidosis. The central chemoreceptors are highly sensitive to these changes and respond by stimulating the respiratory center to increase the rate and depth of breathing. This response helps to expel more CO2, thereby adjusting blood pH back to normal levels.

Hypocapnia, on the other hand, occurs when there are low levels of CO2 in the blood. Central chemoreceptors can inhibit breathing in response to hypocapnia to avoid excessive alveolar ventilation and maintain homeostasis.

The other options, although related to respiratory functions, do not directly describe the primary role of central chemoreceptors in regulating respiratory responses as precisely as hypercapnia and hypocapnia do. This makes those options less fitting when specifically addressing the critical function of central chemoreceptors in response to changes in carbon dioxide levels.