Overview.
Three sensory systems associated with the nose and mouth—olfaction, taste, and the trigeminal chemosensory system—are dedicated to the detection of chemicals in the environment. The olfactory system detects airborne molecules called odors. In humans, odors provide information about food, self, other people, animals, plants, and many other aspects of the environment. Olfactory information can influence feeding behavior, social interactions and, in many animals, reproduction. The taste (or gustatory) system detects ingested, primarily water-soluble molecules called tastants. Tastants provide information about the quality, quantity, pleasantness, and safety of ingested food. The trigeminal chemosensory system provides information about irritating or noxious molecules that come into contact with skin or mucous membranes of the eyes, nose and mouth. All three of these chemosensory systems rely on receptors in the nasal cavity, mouth, or on the face that interact with the relevant molecules and generate receptor and action potentials, thus transmitting the effects of chemical stimuli to appropriate regions of the central nervous system.
