Which receptor type is responsible for chemical senses such as taste and smell?

• A. Photoreceptors
• B. Nociceptors
• C. Mechanoreceptors
• D. Chemoreceptors

Answer: (D)

Chemoreceptors are the sensors for chemical stimuli, making them responsible for chemical senses such as taste and smell. In the nose, olfactory receptor neurons detect airborne odorants; when these molecules bind to their receptors, they trigger signaling cascades that generate nerve impulses sent to the brain. In the mouth, taste receptor cells within taste buds respond to tastants (sweet, sour, salty, bitter, umami) through different transduction mechanisms—some involve ion channels (salt, sour) and others involve ligand-activated GPCRs (sweet, umami, bitter). This chemical detection, rather than light or mechanical energy, is what underlies how we perceive flavors and odors. Photoreceptors handle vision, nociceptors respond to painful stimuli, and mechanoreceptors sense mechanical forces like touch, pressure, and vibration.