Taste buds: types, characteristics and function.
A review of the types of taste buds, their location on the tongue and their associated flavors.
The senses refer to the physiological mechanism of sensation, and allow us to obtain information about what is happening around us, as well as certain internal states of the organism itself. The sense of sight seems to be the most important of all because, with 130 million photosensitive cells distributed in each eye, these complex apparatuses allow us to locate our figure and actions in 3 dimensions, with all that this entails.
Although smell and taste may seem less relevant than sight itself, can you imagine how humans could have evolved without a sense that warns us that what we are ingesting is dangerous? Disgust is a primal sensation present in many animals, since the regurgitation of a toxic or harmful element, in many cases, can save the life of the individual.
Thus, the taste buds and the sense of disgust are a primal sensation present in many animals, taste buds and the sense of taste in general play a much more important role at the evolutionary level than one might initially expect. at first. If you want to know all about taste buds, read on.
What are taste buds?
Taste buds are defined as a set of sensory receptors, specifically referred to as taste receptors.. They are located on the tongue and are the main promoters of taste, that sense that allows us to enjoy food and discriminate those elements that are not edible. The papilla refers to the skin fold on the tongue, but what really encodes the "understanding" of taste are the taste buds found there.
On average, a healthy adult individual has about 10,000 taste buds distributed in taste buds, which regenerate approximately every 2 weeks. Unfortunately, as time goes by, these structures degrade. An elderly person has half as many buttons as a young person, which is why it is sometimes more difficult for older people to identify certain tastes. Smokers have the same problem, as exposure to tobacco smoke reduces the proportion of these cells.
What are taste buds?
As mentioned above, taste buds are the sensory cells of the taste buds, taste buds are the sensory cells present in the papillae responsible for transmitting the signals that translate into taste itself.. Each taste bud is formed by the association of about 50-100 cells, known as taste receptor cells (TCR). In mammals, taste buds are widely distributed throughout the tongue, soft palate and oropharynx.
These curious taste buds are ovoid in shape, 50 to 60 microns high and 30 to 70 microns high. In each taste bud we find 3 cell types, whose characteristics and functions are different. We present them in the following list:
- Type I: they are thin and dense, with a supporting function. They also function as glia and present ionic currents involved in the transduction of salty taste (60% of the total).
- Type II: clear and thin, with small villi at their apical end. They have transduction receptors for sweet, bitter and umami taste (30% of the total).
- Type III: similar to the previous ones, but present synaptic vesicles in the central area. They mediate the transduction of sour taste (10% of the total).
In general, two possible neuronal models are described to explain the functioning of the taste buds. To keep things simple, the first postulates that a taste receptor cell by itself detects a single basic taste modality and is innervated by individual nerve fibers that transmit the signals of that single modality (this is known as a labeled line). Once these cells are stimulated, the information is sent as an action potential to the brain.
In the other model, known as the computational model, individual taste receptor cells detect one or more taste modalities, and the fibers transmit signals from multiple modalities at once. It is, therefore, a more intricate complex of activity than the previous case.
Types of taste buds
Once we have explored the world of taste buds, we can return to the papillae. It is time to clarify that there are 4 types of them, and we will tell you about them briefly below.
1. Fungiform papillae
They are so called because they have the shape of a mushroom, no more and no less. They are rare in many animals and are located on the tip of the tongue.. It is interesting to know that they are not only found in humans, but also in other mammals. They are much more numerous in carnivores and of reduced occurrence in bovids and horses.
Composed of a head and a pedicel, this type of papillae are very visible, due to the reddish color given by the Blood vessels that irrigate them. This type of papillae are much more stimulated in old age and early stages of development, because are mainly specialized in the processing of sweet taste.. According to various sources, this type is the one of gustatory nature most represented in the human species.
2. Calciform papillae
Also known as circumvallate papillae, are a large and underrepresented type of papilla, but with a vital importance: they detect bitter taste.. They are found in a number of 11 in a V-shaped arrangement on the back of the tongue, near the tonsils, and can be clearly seen as "bumps" or lumps.
In addition to their detection of bitter tastes, they also have a number of minor salivary glands that aid in the digestion process. We say that they are the most important papillae because they detect the bitter taste, which, in many cases, can represent a dangerous ingestion. In addition to this, as they are located in the farthest part of the tongue, they contribute to the gag reflex.
3. Filiform papillae
Filiform papillae have a conical/cylindrical shape and end in a crown of filaments, which gives them their characteristic name. They are distributed over the entire surface of the tongue, always arranged in a parallel series, running obliquely from south to south. running obliquely from the middle groove of the tongue to the edges of the tongue. They are the most abundant type within the tongue but, curiously, their function is not to interpret flavors.
Filiform papillae act as a covering for the tongue. They make the tongue present a rough and abrasive structure, which helps us to clean the mouth, swallow and speak. Simply put, they act as physiological "handles" in multiple oral processes. Their thermal and tactile function is mainly stimulated during the adult period of the individual.
4. Foliated papillae
Foliated papillae or foliaceous papillae appear as short vertical folds, present parallel to each other on both sides of the back of the tongue. These appear in the form of symmetrical ridges, in a numbering of 4-5 folds, depending on the individual. Their receptors capture salty tastes.
An overview of the tongue
Let's do a little final review, as we have introduced a lot of terminology that requires a "mind map". Imagine your own tongue in the mirror. At the tip, the fungiform papillae, which are responsible for interpreting sweet tastes, are agglutinated.
If you move to the back, near the bell, you will find 11 large papillae arranged in a V-shape, which are in charge of processing the bitter taste and promote vomiting when the ingested item can be ingested.They are responsible for processing the bitter taste and promoting vomiting when the ingested element may be harmful to the organism.
On the sides and looking at the base of the tongue, we find a series of folds in which the foliated papillae are a series of folds, in which the foliated papillae are located.. These are in charge of capturing salty tastes.
However, as we have seen above, each taste bud contains multiple cells in charge of identifying different types of tastes and, according to the computational model, each taste bud would send information from more than one taste bud, each button would send information about more than one taste to the relevant nerve ending.. In that case, the "taste map" described here would be of little use to us, since it is postulated that each papilla may contain all or some of the cells that interpret certain tastes. In any case, the lingual map helps us to understand the arrangement of the types of papillae and to get a general idea of their function.
Summary
As you may have read in these lines, the world of taste buds gives a lot to talk about. There are certain discrepancies and debates, because the truth is that, even today, we still do not know some of the particularities of the sense of taste..
Even so, it is clear that it has been essential for the development and permanence of the human species throughout time. Taste buds have allowed us to discriminate dangerous foods from nutritious ones, allowing us to develop physically thanks to an adequate caloric intake. In the human body, every cell counts.
Bibliographic references:
- Ariza, A. C., Sánchez-Pimienta, T. G., & Rivera, J. A. (2018). Taste perception as a risk factor for childhood obesity. public health of mexico, 60, 472-478.
- Fuentes, A., Fresno, M. J., Santander, H., Valenzuela, S., Gutiérrez, M. F., & Miralles, R. (2010). Gustatory sensoperception: a review. International journal of odontostomatology, 4(2), 161-168.
- Hernández Calderón, M. L., & Díaz Barriga Arceo, S. (2020). The biochemistry and physiology of taste. Journal of Biochemical Education, 38(4), 100-104.
- Oral, I. C., & Faringe, E. Physiology of taste.
- Smith, D. V., & Margolskee, R. F. (2001). The sense of taste. Research and Science, 296, 4-12.
(Updated at Apr 13 / 2024)