Chemesthesis is the chemical sensitivity of the skin and mucous membranes. Chemesthetic sensations arise when

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s activate receptors associated with other

sense A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system re ...

s that mediate pain,

touch In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch ( haptic perception), as well as temperature ( thermoception), body position (proprioception), and pain. It ...

, and thermal perception. These chemical-induced reactions do not fit into the traditional sense categories of

taste The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...

and smell. Examples of chemesthetic sensations include the burn-like irritation from

capsaicin Capsaicin (8-methyl-''N''-vanillyl-6-nonenamide) ( or ) is an active component of chili peppers, which are plants belonging to the genus ''Capsicum''. It is a chemical irritant for mammals, including humans, and produces a sensation of burnin ...

and related compounds in foods like

chili pepper Chili peppers (also chile, chile pepper, chilli pepper, or chilli), from Nahuatl '' chīlli'' (), are varieties of the berry-fruit of plants from the genus ''Capsicum'', which are members of the nightshade family Solanaceae, cultivated for ...

s; the coolness of menthol in mouthwashes and topical analgesic creams; the stinging or tingling of carbonated beverages in the nose and mouth; the tear-induction of cut onions; and the pungent, cough-inducing sensation in the back of the throat elicited by the oleocanthal in high-quality

extra virgin olive oil Olive oil is a liquid fat obtained from olives (the fruit of ''Olea europaea''; family Oleaceae), a traditional tree crop of the Mediterranean Basin, produced by pressing whole olives and extracting the oil. It is commonly used in cooking: f ...

. Some of these sensations may be referred to as spiciness,

pungency Pungency () refers to the taste of food commonly referred to as spiciness, hotness or heat, found in foods such as chili peppers. Highly pungent tastes may be experienced as unpleasant. The term piquancy () is sometimes applied to foods with a l ...

, or piquancy. Chemesthetic sensations sometimes arise by direct chemical activation of ion channels on sensory nerve fibers, for example of

transient receptor potential channel Transient receptor potential channels (TRP channels) are a group of ion channels located mostly on the plasma membrane of numerous animal cell types. Most of these are grouped into two broad groups: Group 1 includes TRPC ( "C" for canonical), TR ...

s including those of the TRPV, TRPA or

TRPM TRPM is a family of transient receptor potential ion channels (''M'' standing for '' wikt:melastatin''). Functional TRPM channels are believed to form tetramers. The TRPM family consists of eight different channels, TRPM1–TRPM8. Unlike the TRPC ...

subtypes. Alternatively, irritant chemicals may activate cells of the epithelium to release substances that indirectly activate the nerve fibers. The respiratory passages, including the nose and trachea, possess specialized cells called solitary chemosensory cells which release acetylcholine or other activators to excite nearby nerve fibers. Because chemoresponsive nerve fibers are present in all types of skin, chemesthetic sensations can be stimulated from anywhere on the body's surface as well as from mucosal surfaces in the nose, mouth, eyes, etc. Mucus membranes are generally more sensitive to chemesthetic stimuli because they lack the barrier function of cornified skin. Much of the chemesthetic flavor sensations are mediated by the trigeminal nerves, which are relatively large and important nerves. Flavors that stimulate the trigeminal nerves are therefore important - for example, carbon dioxide is the trigeminal stimulant in carbonated beverages.

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Further reading