Body processes

Sense of Taste – Function, Task & Diseases

Sense of taste

Taste is a chemical sense that can be used to determine the precise nature of substances, especially food . In humans, the sensory cells of taste are located in the oral cavity , above all on the tongue , but also in the mucous membrane of the mouth and throat .

What is the sense of taste?

The sense of taste, like the sense of smell , is a chemical sense that serves to absorb chemical stimuli from the environment. In contrast to the sense of smell, the sense of taste is a near sense, since it can only pick up stimuli from a substance if it comes into direct contact with it.

The perception of the stimulus takes place via specific chemical components of the substance, which stimulate precisely assigned taste sensory cells. The taste stimulus is then passed on to the brain via the taste buds and evaluated there. There is a close connection with olfactory information that is perceived at the same time.

The final taste of a substance is therefore composed of chemical taste and smell information as well as the temperature and tactile perceptions from the oral cavity .

Basic tastes recognized at the current state of science are sweet, sour, salty, bitter and umami (spicy). The fatty flavor is also currently being investigated and seems to be confirmed. The specific perception of the tastes metallic, water-based and alkaline is also tested.

Function & task

Human taste receptor cells are located in the taste buds . Each bud contains between 50 and 150 taste buds. The taste buds are 75 percent distributed on the tongue. The rest is found in the mucous membranes of the oral cavity and pharynx , on the upper esophagus , larynx and soft palate .

Infants and young children not only have a greater number of taste buds than adults. In addition, the buds are also distributed in the middle of the tongue, in the mucous membrane of the lips and cheeks and on the hard palate. With increasing age, the number and distribution of taste buds continues to decrease.

The taste buds are arranged in differently shaped taste buds on the tongue. Around half of all the taste buds in the mouth are located in the back third of the back of the tongue. Wall papillae contain several thousand taste buds in a V-shaped arrangement near the base of the tongue.

Also in the back third of the tongue are the leafy papillae with several hundred taste buds at the edge of the tongue. Fungal papillae are found primarily on the front two-thirds of the tongue. There are up to 400 of them, each containing three to five taste buds.

Each receptor cell can only perceive a specific taste. In the taste buds, however, receptor cells for different flavors are always arranged together. This ensures that each area of ​​the taste buds can respond to all possible taste nuances.

This comprehensive ability to react can be explained by the vital importance of the sense of taste: it allows people to check the ingredients of the substances they have ingested before they actually take them.

A sour or bitter taste can indicate immature or fermented or even toxic food. The flavors sweet, salty, umami and fatty often indicate the nutritional components contained, such as carbohydrates, minerals, proteins and fats. This makes it easier to select needed and avoid harmful foods.

If the taste buds are stimulated by the components of an ingested substance, this information is passed on via the taste buds . These unite to form a total of three major cranial nerves : the facial nerve , the glossopharyngeal nerve and the vagus nerve . These are also denoted by the numbers VII, IX and X and direct the taste perceptions to the brain.

Diseases & Ailments

Disorders of the sense of taste are medically called dysgeusia . When the sense of taste is quantitatively impaired, a person may be hypersensitive (hypergeusia) or have reduced sensitivity (hypogeusia).

A qualitative impairment is evident in taste sensations without a triggering stimulus (phantogeusia) or in altered taste sensations (parageusia). If, for example, the taste sensations are changed in such a way that everything tastes unpleasant, doctors speak of cacogeusia.

Causes of disorders of the sense of taste can be divided into three areas: On the one hand, dysgeusia can occur due to epithelial damage to the taste buds. On the other hand, the taste buds can be damaged by flu infections or radiation therapy in the head area, among other things.

The taste buds can also be damaged by diabetes mellitus , liver and kidney diseases , hypothyroidism or inflammation of the oral mucosa or tongue.

The intake of numerous active ingredients can also affect the sense of taste. These are, for example, penicillamine, chlorhexidine , terbinafine and cytostatics . Cushing’s and Sjögren ‘s syndromes are other possible causes of dysgeusia, as is poor oral hygiene .

Damage to cranial nerves VII, IX or X can also trigger a taste disorder. The transmission of taste sensations through these nerves can be disturbed by tumors or inflammatory nerve diseases . An injury to the taste buds is also possible as a result of a skull base fracture or during operations on the teeth , ears , palatine tonsils or cervical lymph nodes .

The third area that can affect the sense of taste includes central nervous causes. It affects the so-called “taste pathway”, i.e. the path that the taste stimulus takes in the central nervous system . Disorders can result from injuries to the brainstem or brain tumors. Certain forms of epilepsy or neurodegenerative diseases such as Alzheimer’s can also affect the sense of taste. Some poisonings also affect the sense of taste.

An indirect impairment of the sense of taste also occurs through a disturbance of the sense of smell. Even a simple inflammation of the nasal mucosa ( cold ) can therefore cause a clearly perceived deterioration in taste. The reason for this is the combined processing of taste and smell information into a complex taste image in the brain.

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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.