Peripheral chemoreceptors that detect changes in blood oxygen levels are primarily located in the carotid bodies at the bifurcation of the carotid arteries and the aortic bodies near the aortic arch. These structures are sensitive to hypoxemia and respond by stimulating the respiratory centers to increase ventilation. This mechanism is crucial for maintaining adequate oxygenation, especially during conditions like chronic lung disease or high altitude exposure. The medulla oblongata contains central chemoreceptors sensitive mainly to CO2 and pH, not oxygen. Understanding the location of these peripheral chemoreceptors is key during surgeries involving the neck or thoracic region to avoid compromising respiratory regulation.

Reference: Guyton and Hall Textbook of Medical Physiology, Arthur C. Guyton, Edition 13.