Peripheral chemoreceptors respond mainly to which factors?

Peripheral chemoreceptors primarily respond to changes in the levels of oxygen (O2), carbon dioxide (CO2), and hydrogen ions (H+), which is why this choice is the correct answer. Located mainly in the carotid bodies and aortic bodies, these receptors play a critical role in regulating respiratory rate and depth in response to the chemical composition of the blood.

When blood oxygen levels drop (hypoxia), peripheral chemoreceptors stimulate an increase in ventilation rate to enhance oxygen uptake. Elevated levels of carbon dioxide (hypercapnia) also trigger these receptors as the body seeks to eliminate excess CO2 through increased respiratory effort. Additionally, a rise in hydrogen ion concentration, indicating a drop in pH (acidosis), activates peripheral chemoreceptors to adjust breathing patterns and restore pH balance by expelling more CO2, which shifts the bicarbonate equilibrium.

The other factors mentioned in the incorrect choices do not have the same direct influence on peripheral chemoreceptor activity. For example, while blood volume is important for overall circulation, it does not directly modify the chemoreceptors' response to respiratory drive in the same manner as O2, CO2, and H+. Temperature and humidity, while they can have effects on a variety of physiological processes