Explain in detail Why PCO2 and pH levels affect respiration more than PO2 levels.
Central chemoreceptors are located in the medulla oblongata. That's in the central nervous system (CNS). On the other hand, there are also peripheral chemoreceptors. They are located in the walls of certain arteries throughout the body. These relay messages to the respiratory center in the brain through pathways involving parts of the peripheral nervous system (PNS).
The central chemoreceptors respond to changes in H+, pCO2 or both -- only. H+ is the chemical whose concentration is measured to give the pH. The more H+, the lower the pH.