Chemoreceptors are located in which of the following areas?

• A. Carotid bodies
• B. Aortic arch
• C. Medulla
• D. All of the above

Answer: (D)

Chemoreception for breathing uses both peripheral and central sensors. The carotid bodies, located at the split of the carotid arteries, house peripheral chemoreceptors that monitor arterial blood gases and pH, especially when oxygen levels fall. The aortic arch contains another group of peripheral chemoreceptors that contribute to this sensing. In the brainstem, central chemoreceptors sit in the medulla and respond mainly to CO2-driven changes in cerebrospinal fluid pH, helping set the baseline and adjust ventilation accordingly. Because all these areas have chemoreceptors, the correct statement is that chemoreceptors are located in all of them.