Does a decrease in O2 cause an increase or decrease in the CO2 sensitivity of peripheral chemoreceptors in the carotid and aortic arch?

A decrease in oxygen (O2) levels leads to an increase in the carbon dioxide (CO2) sensitivity of peripheral chemoreceptors located in the carotid and aortic arch. These chemoreceptors play a significant role in sensing changes in blood gases and adjusting respiratory drive accordingly.

When oxygen levels drop, the body's need for adequate gas exchange intensifies. The peripheral chemoreceptors respond primarily to low O2 levels, and this response can enhance their sensitivity to CO2 levels as well. Specifically, the presence of low O2 can amplify the peripheral chemoreceptors' signaling pathways that promote respiratory activity in order to increase oxygen uptake and carbon dioxide clearance. Essentially, the chemoreceptors become more responsive to fluctuations in CO2 when oxygen is scarce, making them more sensitive to CO2 levels.

This heightened sensitivity ensures that the body can maintain homeostasis and respond rapidly to changes in respiratory demands, especially during situations where oxygen availability is compromised. Thus, the correct answer reflects this physiological adaptation.