Taste buds are composed of groups of between 50 and columnar taste receptor cells bundled together like a cluster of bananas. The taste receptor cells within a bud are arranged such that their tips form a small taste pore, and through this pore extend microvilli from the taste cells.
The microvilli of the taste cells bear taste receptors. Interwoven among the taste cells in a taste bud is a network of dendrites of sensory nerves called " taste nerves ". When taste cells are stimulated by binding of chemicals to their receptors, they depolarize and this depolarization is transmitted to the taste nerve fibers resulting in an action potential that is ultimately transmitted to the brain.
One interesting aspect of this nerve transmission is that it rapidly adapts - after the initial stimulus, a strong discharge is seen in the taste nerve fibers but within a few seconds, that response diminishes to a steady-state level of much lower amplitude. Once taste signals are transmitted to the brain, several efferent neural pathways are activated that are important to digestive function. For example, tasting food is followed rapidly by increased salivation and by low level secretory activity in the stomach.
Among humans, there is substantial difference in taste sensitivity. Roughly one in four people is a "supertaster" that is several times more sensitive to bitter and other tastes than those that taste poorly.
Such differences are heritable and reflect differences in the number of fungiform papillae and hence taste buds on the tongue. In addition to signal transduction by taste receptor cells, it is also clear that the sense of smell profoundly affects the sensation of taste. Think about how tastes are blunted and sometimes different when your sense of smell is disrupted due to a cold.
The sense of taste is equivalent to excitation of taste receptors, and receptors for a large number of specific chemicals have been identified that contribute to the reception of taste. Despite this complexity, five types of tastes are commonly recognized by humans:. None of these tastes are elicited by a single chemical. Also, there are thresholds for detection of taste that differ among chemicals that taste the same.
A similar transduction process converts non-polar solutes into nerve impulses. Many drugs are non-polar solutes and some are bitter in taste. Neural input from one taste bud does not transmit directly through a single axon into the central nervous system, instead many taste cells in many taste buds are stimulated by the diverse quality of masticated food.
A deficiency in the function of taste may be caused by age, drugs, disease, or trauma. For example as humans age, there is a decrease in the number of papillae containing taste buds and a reduction in the sensitivity to many taste solutes; however, older people still enjoy sweet, tasting foods. The role of saliva in taste perception is very important because saliva assist in dissolving solutes and in transporting these to the taste pore. It is difficult to taste anything if the mouth is dry.
Patients that receive radiation treatment for oral cancer have a severe deficiency in taste because the treatment produces salivary gland atrophy and reduces the number of tongue papillae.
These patients will complain of oral soreness and the loss of taste. Neural trauma to one of the afferent cranial nerves for taste e. Content provided by Dr. Submit an Idea. Brand Logo. All rights reserved. Terms Of Use. Privacy Policy. About Our Ads. Children's Privacy Policy. Sign up now. Search Box Clear. Want more tips and offers sent directly to your inbox? Products Categories Goals Brands. Our Commitment Our Bright Smiles, Bright Futures program brings oral health education to more than half a billion children around the world.
Learn more about our commitment to oral health education. Circumvallate Papillae: Tastebuds, Function, and Complications. Top Articles. Circumvallate Papillae: What You Should Know Your tongue is a vital part of your biology that assists in eating, speaking, and tasting.
Your four types of papillae include: Circumvallate papillae : Also known as vallate papillae, of these are located on the backside of your tongue, containing over taste buds each. Fungiform papillae : Over are found on the front side of your tongue and contain taste buds each.
Foliate papillae : are positioned on the side of your tongue in the creases that contain over taste buds each.
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