Peripheral chemoreceptors are specialized sensory cells located primarily in the carotid bodies and aortic bodies. They play a crucial role in monitoring the levels of oxygen, carbon dioxide, and pH in the blood. When these levels change, the chemoreceptors send signals to the respiratory center in the brain, helping to regulate breathing and maintain homeostasis. These receptors are sensitive to low oxygen levels (hypoxia) and high carbon dioxide levels (hypercapnia). When they detect these changes, they stimulate an increase in breathing rate and depth, ensuring that the body receives adequate oxygen and removes excess carbon dioxide efficiently.