gustativa

Gustativa refers to the gustatory sense, or the sense of taste, and to the sensory system and processes that detect and interpret tastants in the mouth. In biology, gustation is the chemical sense that contributes to flavor perception together with smell, texture, and temperature.

Taste perception is mediated by taste buds, small clusters of specialized receptor cells embedded mainly on the tongue’s surface within the papillae (fungiform, circumvallate, and foliate), but also in the palate, epiglottis, and pharynx. Each taste bud contains multiple gustatory receptor cells with microvilli that extend into taste pores to sample tastants. The epithelium also contains supporting and basal cells to maintain function and renewal.

Humans recognize five basic tastes: sweet, sour, salty, bitter, and umami, with ongoing discussion about additional tastes such as fat. Receptors for these tastes differ: sweet, umami, and bitter involve G-protein coupled receptors (for example T1R1/T1R3 for umami, T1R2/T1R3 for sweet, and T2Rs for bitter); salty and sour mainly involve ion channels that respond to ionic tastants. When tastants bind or enter receptor cells, they depolarize the cells and trigger neurotransmitter release, notably ATP, which activates afferent gustatory neurons. The primary sensory nerves conveying taste information are the facial nerve (cranial nerve VII) for the anterior two-thirds of the tongue, the glossopharyngeal nerve (IX) for the posterior third, and the vagus nerve (X) for taste in the epiglottis and lower pharynx.

Central processing involves the nucleus of the solitary tract in the medulla, the ventral posteromedial nucleus of the thalamus, and finally the gustatory cortex in the insula and frontal operculum. Taste perception integrates with olfaction, texture, and temperature to form flavor. Variations in gustativa can arise from genetics, health, aging, and medication, and disorders such as ageusia, hypogeusia, and dysgeusia are clinically recognized.