Anatomy and Chemistry Basics
The Sensory System
The sense of taste, or gustatory sense, occurs in the taste buds. Located primarily on the tongue, taste buds reside in papillae, the bumps on the tongue that give it a rough texture. The taste bud consists of supporting cells, basal cells, and gustatory (taste) receptor cells arranged in the shape of a glove with an opening, or taste pore, to the outside located at the top. A long microvilli, or gustatory hair, from each gustatory receptor cell within the taste bud projects through the taste pore. Gustatory hairs generate action potentials when stimulated by chemicals that are dissolved in the saliva.
Basal cells are actively dividing epithelial cells. The daughter cells of basal cells develop into supporting cells, which subsequently mature into gustatory receptor cells. Because they are easily damaged by the activities that occur in the mouth, gustatory receptor cells are short-lived and replaced about every ten days.
An individual gustatory receptor cell responds to only four taste sensations: sweet, bitter, sour, and salty. All other tastes arise from a mixture of these four tastes in combination with olfactory sensations associated with the substance tasted. Taste buds on certain areas of the tongue seem to specialize for certain tastes. For example, the sensation of sweetness is best detected at the front of the tongue, while bitterness is best detected at the back of the tongue.
