TASTE BUDS: STRUCTURE, FUNCTIONS, TYPES AND DISORDERS - ANATOMY AND PHYSIOLOGY - 2025

The taste buds are small sensory organs located in epithelial tissue of the tongue of terrestrial vertebrate animals. They fulfill the function of emitting signals to the brain about the stimuli that reach the interior of the oral cavity, which are translated into flavors such as sweet, salty, acid, bitter and umami (Bernays & Chapman, 2016).

Taste buds can have a conical, cylindrical, or mushroom shape depending on their size and function. Different types of papillae are located in different parts of the tongue, making the sensitivity to one flavor more predominant than to another depending on the area of ​​the tongue to which the stimulus reaches.

Localization of flavors on the tongue

A human being has an average of 10,000 taste buds on the tongue, which regenerate every two weeks or so. As a human ages, the number of functional taste buds can drop to 5,000. For this reason, some foods taste stronger for children than for adults. (Dowshen, 2013).

Functions and operation

OpenStax The function of the taste buds is the perception of flavors; sour, bitter, sour, salty and sweet.

The functioning of the taste buds is highly dependent on smell. Most flavors are perceived thanks to the joint function of both the taste receptor cells in the taste buds and the receptor organs located inside the nose.

Historically, five different flavors have been classified that can be identified by human taste buds. However, the oily or oleogustus flavor has now been called the sixth flavor that can be identified by sensory receptors located on the taste buds.

From a biological point of view, the existence of taste buds is attributed to the survival of the species. Bitter and sour flavors are associated with poisonous or spoiled foods, while sweet and salty flavors represent the energy and nutrient intake necessary for the proper functioning of the body.

Location and structure

Taste bud in which 6 taste buds can be observed. Possible2006

The papillae are located mainly on the tongue and soft palate. Most papillae found on the tongue are not linked to the sense of taste and have a rounded shape giving the tongue a velvety appearance.

These papillae, in general, do not have the necessary structure to perceive flavor and are used only to perceive tactile stimuli.

The taste buds have a structure similar to that of an onion. Each papilla contains between 50 and 100 taste cells that have finger-shaped projections called microvilli.

These microvilli appear through the opening in the highest part of the papilla called the taste button or gustatory nerve where they receive the chemicals from food dissolved in saliva. (Smith & Margolskee, 2001)

The taste cells, located inside each papilla, are supported by support cells that curve slightly above them.

Structure of a taste bud (Health, 2016)

Types

Antimoni

Fungiform papillae

The fungiform or mushroom-shaped papillae are found on the front of the tongue and are the easiest to differentiate from the rest of the papillae.

These papillae have a characteristic pinkish color, a bulky head and are distributed over the entire surface of the tongue, mainly in front of the goblet papillae. This type of papillae is usually used to perceive the sweet taste.

Foliated papillae

The foliate or filiform papillae are conical in shape, similar to that of a flask. Apart from being receptors of salty and acid flavors, they exert a tactile and thermal function on the entire surface of the tongue.

Circumvated papillae

Circumvated or goblet papillae are located at the back of the tongue, where the throat begins. Each person has between 7 and 12 large circumvated papillae, responsible for perceiving the bitter taste.

These papillae are distributed near the base of the tongue in an inverted "V" shape.

Similarly, taste buds sensitive, to a lesser extent, to bitter taste can be found located in small lateral trenches on the back of the tongue. (Health, 2016).

Filiform papillae

The filiform papillae, also called conical papillae, are sensory receptors that are distributed over two thirds of the lingual dorsum. They are the most abundant papillae on the surface of the tongue, and are not associated with the reception of flavors.

Taste reception

Gabrielzerrisuela

When a stimulus enters the oral cavity, it can affect receptors located on the membrane of taste cells, pass through specific channels, or activate ion channels. Any of these processes generates a reaction in taste cells, causing them to release neurotransmitters and send a signal to the brain.

Currently it is not fully understood how each different type of stimulus generates a response in the taste organs. Sweet and sour flavors are perceived through receptors linked to the G protein, T1R and T2R. There are different points and sets of taste cells that perceive sweet and sour tastes on the tongue.

However, it has been found that not all receptors perceive flavors with the same intensity.

Some studies on the reception of the salty taste have indicated the presence of ion channels as those responsible for depolarizing the taste cells so that they release neurotransmitters.

The reception of the acid taste was initially linked to the concentration of hydrogen ions. However, it has been shown that there is no direct relationship between pH, free acidity and acid taste, as different solutions of organic acids with the same pH level have shown dissimilar taste responses. (Roper, 2007)

Types of flavors and receptors

Location of taste receptors. From left to right: sweet, sour, salty and acid Distribution and types of papillae (Health, 2016)

It is estimated that the sense of taste developed in vertebrate animals 500 million years ago, once the creatures acquired the ability to perceive their prey in the ocean by locating it around them, devouring it and appreciating its flavor.

Currently five basic flavors identifiable by the taste buds have been identified: sweet, bitter, salty, sour and umami.

Each papilla is capable of recognizing a different type of taste with greater intensity than the others thanks to the proteins found inside, called taste cells.

These cells identify the molecules that make up the drinks and food that enter the oral cavity as stimuli. When receiving a taste, the cells are responsible for emitting signals to the brain that later produce the sensation of like or dislike.

Sweet

It is the most elemental pleasure-generating flavor. The sweet taste indicates the presence of sugars in the food. Currently, the highest percentage of foods consumed are rich in sugars, therefore, fungiform taste cells tend to be the most stimulated.

Bitter

It is a red flag. Bitter taste is associated with dislike for food, and is generally accompanied by a spastic response from the body and disgust.

There are hundreds of bitter substances, mainly from plants. Some of these substances in small concentrations are pleasant in certain foods or drinks.

Some of the antioxidant substances that help the functioning of the metabolism and prevent the formation of tumors, are generally found in foods or beverages with a bitter taste such as coffee.

Salty

The human brain is programmed to enjoy the salty taste in minimal concentration. However, a high concentration of salt can be unpleasant. This relationship with the salty taste ensures the consumption of salts, which provide the body with some of the nutrients and substances it needs to function properly.

The taste of salt can be addictive, and taste buds can adapt to both high and low concentrations of salt in food.

Acid

It is believed that the acid taste was previously associated with the state of decomposition of food, indicating that a product with an acid taste was not suitable for consumption as it could be harmful to the body. There is not much scientific information on the biological principles of this flavor.

Umami

It is defined as an intense and pleasant flavor produced by certain amino acids present in cured meats, mature cheeses, green tea, soy sauce and cooked tomatoes, among other foods.

The word Umami comes from the Japanese term used to describe those delicious flavors. (Mcquaid, 2015)

Other flavors

Different investigations are currently being conducted that seek to find other types of specialized taste cells to receive taste stimuli other than the five already classified. These flavors are fatty, metallic, alkaline, and water.

Oleogutus

Research conducted in Indiana by Purdue University indicates that the fat taste should be classified as a sixth taste capable of being detected by the taste buds. This new flavor has been called oleogustus. (Patterson Neubert, 2015).

Purdue University maintains that the tongue has a sixth type of taste receptor capable of detecting foods with a higher concentration of linoleolic fatty acids and that the attraction that humans feel for consuming foods high in fatty acids is not due only to its texture or smell, but also its taste.

Foods rich in fatty acids are usually made up of triglycerides, which are molecules made up of three types of fatty acids. However, triglycerides are not stimulants of taste receptor cells, so it is believed that by entering foods rich in fatty acids into the oral cavity and mixing with saliva, the fatty acids present in triglycerides are divided, making it possible to the papillae the perception of them.

Hot spicy

In the case of spicy, there is no evidence of any kind of response from the taste buds when it is eaten. This stimulus activates a group of receptors known as nociceptors, or pain pathways that are only activated in the presence of some element that can be harmful to the tissue.

Spicy is believed to be a flavor, since the contact that one has with this stimulant occurs inside the oral cavity.

Taste disorders and their factors

The sense of taste is one of the most important senses for human beings. Any alteration in the perception of flavors is of great importance as it directly affects people's eating habits and health.

There are some internal and external factors that affect the sense of taste, such as cigarettes, the intake of certain foods or drinks, the amount of saliva present in the mouth, age, gender, and conditions in the nervous or respiratory system.

Cigarette

Tobacco use can numb the sense of taste, affecting the type of information that taste receptor cells send to the brain. This is due to the toxic action exerted by the chemicals present in the cigarette when interacting with the tongue.

The taste buds lose their shape and become flat due to a vascularization process. The number of taste buds, however, does not decrease, it just ceases to function properly.

Saliva

Saliva works as a propagation medium for chemicals released by food once it is chewed. Low salivary volume or infection of the salivary glands affects the dispersal of these chemicals, reducing the chances that they will be perceived by the taste receptor cells.

Age and gender

There are some differences in the perception of flavors depending on gender and age. Men tend to be more sensitive to sour taste, and older women tend to retain the perception of sour and salty tastes to a greater extent than men. It is estimated that people over 80 years of age have taste disorders in most cases (Delilbasi, 2003).

Nervous system

There are certain disorders of the nervous system that can alter the sense of taste, since they affect the way messages are sent from the taste receptor cells to the brain.

Respiratory system

Conditions in the respiratory system can cause disorders in the taste buds. Illnesses like the flu, sinusitis, or a cold can prevent olfactory receptors and taste receptor cells from working together to send the brain the signals it needs to identify a taste.

References

1. Bernays, E., & Chapman, R. (22 of 4 of 2016). Encyclopedia Britannica. Obtained from Taste Bud.
2. Delilbasi, C. (2003). Evaluation of some factors affecting taste perception. Bagdat: Yeditepe University, Faculty of Dentistry, Department of Oral and Maxillofacial Surgery.
3. Dowshen, S. (10 of 2013). Kids Health. Obtained from What Are Taste Buds ?.
4. Health, I. (17 of 8 of 2016). US National Library of Medicine. Obtained from How does our sense of taste work ?.
5. Mcquaid, J. (15 of 5 of 2015). For the. Obtained from Flavor 101: The Five Basic Tastes. Extracted from parade.com.
6. Patterson Neubert, A. (23 of 7 of 2015). Purdue. Obtained from Research confirms fat is sixth taste; names it oleogustus. Excerpted from purdue.edu.
7. Roper, SD (2007). Signal transduction and information processing in mammalian taste buds.. European Journal of Physiology, 454, 759-776.
8. Smith, DV, & Margolskee, RF (2001). Making Sense of Taste. Scientific American, 32-35.