Chemoreceptors respond to which type of stimulus?

• A. Chemicals
• B. Heat
• C. Mechanical forces
• D. Light

Answer: (A)

Chemoreceptors respond to chemical stimuli—molecules that can interact with receptors, whether in the environment (such as smell and taste) or inside the body (changes in blood chemistry and CSF). This includes olfactory receptors that detect odorants, taste receptors that sense tastants, and peripheral chemoreceptors in places like the carotid bodies and central chemoreceptors in the brainstem that monitor CO2, O2, and pH. The idea is that these receptors are activated by chemical composition, not by other physical properties. In contrast, heat is detected by thermoreceptors (temperature changes), mechanical forces are detected by mechanoreceptors (pressure, vibration, stretch), and light is detected by photoreceptors (in the retina).