Anatomy & Organs

Taste buds – structure, function & diseases

Taste buds

Humans have around 10,000 taste buds , of which each individual bud contains 50 to 100 taste-sensing cells that come into contact with the substrate to be tasted via tiny taste pins and then report their information to the central nervous system (CNS) via afferent nerve fibers. About 75% of the buds are integrated into the tongue mucosa, the rest are distributed over the soft palate, nasopharynx, larynx and the upper part of the esophagus.

What are taste buds?

Taste buds ( caliculi gustatorii ) are small cup-like structures in the lining of the tongue . Each taste bud contains, among other things, up to 100 taste sensory cells , which come into contact with the substrate (food) on the tongue via tiny taste pegs ( microvilli ) in the taste pore ( Porus gustatorius ). They transmit their “impressions” as an electrical impulse via afferent nerve fibers to the responsible nerve switching points in the central nervous system .The taste sensory cells can be divided into type I, II and III cells. Taste buds are grouped together on the mucous membrane of the tongue into so-called papillae, which are differentiated into wall, leaf and fungal papillae depending on their appearance.

While wall papillae contain several hundred taste buds, there are only 3 to 5 in the fungal papillae. The taste buds can only distinguish between the tastes sweet, sour, bitter, salty and umami. The term “umami” is a Japanese expression and can be described as a fifth taste with something like meaty, hearty and tasty.

Each taste bud contains sensory cells for all five tastes. The sense of taste is closely linked to the sense of smell . An impaired sense of smell, for example due to a cold , also affects the sense of taste.

Anatomy & Structure

The taste buds with a diameter of 20 to 40 µm are integrated into the epithelium of the oral mucosa . The taste buds have a cup-like shape and taper upwards to the taste pore with a diameter of 4 to 10 µm. Short sensory pins (microvilli) protrude from the taste pore, each of which is connected to “their” taste sensory cell at the other end.The actual taste receptors, which can be stimulated depending on the nature of the food, are located on the membrane surface of the microvilli. Each taste bud contains up to about 100 taste receptors, which connect to the central nervous system with afferent nerve fibers to report their impulses. From the undifferentiated basal cells, which each taste bud contains at its base, new taste-sensing cells continuously develop, as these are relatively short-lived and must be constantly replaced.

The classification of the taste sensory cells into the three cell types I, II and III is based on morphological and immunohistochemical distinguishing features. A distinction according to function and tasks could not (yet) be made because differentiated knowledge about them is not available.

Function & Tasks

The main function of the taste buds is to work with the sense of smell to pre-screen food for toxic/dangerous, edible or inedible criteria. The protective function of protecting the body from toxins or other harmful substances is based partly on genetic pre-programming, but largely on acquired experiences stored in taste and smell memory.

Another important task of the taste buds is to check the food for sugar. On the one hand, the body demands energy in the form of sugar, on the other hand, too much biologically readily available sugar ( glucose ) can drive blood sugar levels to dangerous levels. To prevent this from happening, the taste buds trigger a cascade of physiological reactions with their collected messages “strongly sweet”.

Above all, the pancreas is trimmed for insulin production in order to be able to process the expected sugar quickly and transfer it to a kind of suitable intermediate storage. If the “sweet news” was a hoax because the taste buds fell for sweetener, it messes up the metabolism.

If the insulin level is too high , the glucose level in the blood will drop sharply within 10 to 15 minutes, which can lead to a drastic hypoglycaemia. A fascinating job of the taste buds ensures that natural foods taste particularly good when they contain the minerals, enzymes and vitamins that the body needs at the moment. According to which criteria this works is not known.

Diseases & Ailments

A disturbance of the sense of taste can be caused by pathologically altered taste buds, for example by inflammation in the mucous membrane of the tongue or by a disturbance in the nervous system. The stimuli reported by the taste bud cannot be correctly transmitted or processed in the central nervous system.Taste disturbances are called dysgeusia . A distinction can be made between qualitative and quantitative dysgeusia. A complete loss of taste is called ageusia.

A qualitative dysgeusia is expressed by a changed sense of taste, under certain circumstances even a sense of taste is generated virtually, quasi hallucinated (phantogeusia). A rather unpleasant dysgeusia is cacogeusia, in which all taste stimuli are perceived as unpleasantly foul-tasting. Quantitative dysgeusia usually occurs in connection with impairment of the sense of smell.

Inflammation in the oral mucosa or in the mucosa of the tongue can lead to a temporary impairment of taste and cause quantitative dysgeusia. Nerve inflammation (neuritis) can trigger dysgeusia if the neuritis impedes or completely prevents the transmission of taste impulses.

Disturbances in the processing of nerve impulses in the central nervous system, caused for example by tumors , neurotoxins or alcohol and other drugs, can also lead to dysgeusia. Most dysgeusia associated with secondary diseases such as mucosal inflammation or neuritis are temporary and disappear once the secondary disease has been cured. A permanent total loss of taste sensation is very rare.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.