Final answer:
Central chemoreceptors in the medulla respond to increased levels of CO2 by signaling for an increased respiratory rate and depth, helping to regulate blood pH.
Step-by-step explanation:
Chemoreceptors located in the medulla that respond to CO2 are known as central chemoreceptors. These receptors are highly sensitive to changes in carbon dioxide and hydrogen ion concentrations. When CO2 levels in the blood rise, CO2 readily diffuses across the blood-brain barrier into the extracellular fluid in the brain. This increase in CO2 levels leads to an increase in hydrogen ion concentration, which reduces the pH of the cerebrospinal fluid. The central chemoreceptors respond to these changes by signaling the respiratory centers in the medulla oblongata to adjust the respiratory rate and depth. Increased CO2 prompts an increase in the rate and depth of breathing, helping to expel more carbon dioxide and regulate pH levels within the blood.