Explain why central chemoreceptors are unable to detect decreases in aterial pH

I think it has to do with location. Although the basic rhythm of breathing is established by the respiratory centers, it is modified by input from the central and peripheral chemoreceptors. They respond to changes in the PCO2, pH, and PO2 of arterial blood, which are the most important factors that alter ventilation.

The central chemoreceptors in the medulla monitor the pH associated with CO2 levels within the cerebrospinal fluid in the fourth ventricle. The chemoreceptors synapse directly with the respiratory centers.

The peripheral chemoreceptors are found in two locations:

• The aortic bodies within the aortic arch
• The carotid bodies at the bifurcation of the common carotid arteries

The peripheral chemoreceptors monitor the PCO2, pH and PO2 of arterial blood. This information
travels to the respiratory centers via the vagus and glossopharyngeal nerves.