The senses refer to the physiological mechanism of sensation and allow us to obtain information about what is happening around us, as well as about 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 devices allow us to locate our figure and act in 3 dimensions, with all that that implies.
Even though smell and taste seem less relevant than sight itself, can you imagine how we humans could have evolved without a feeling that warns us that what we ingest is dangerous? Disgust is a primitive sensation present in many animals, as regurgitation of a poisonous or harmful element, in many cases, can save an individual’s life.
Therefore, taste buds and the sense of taste in general play a much larger role in evolution than one might expect in the beginning. If you want to know all about taste buds, keep reading.
What are taste buds?
Taste buds are defined as a collection of sensory receptors, specifically called taste receptors. They are found in the tongue and are the main promoters of taste, this sense that allows us to appreciate food and discriminate between elements that are inedible. The papilla refers to the skin fold we have on the tongue, but what really encodes the “understanding” of taste is the taste buds there.
On the average, a healthy adult individual has around 10,000 taste buds distributed among the taste buds, which regenerate approximately every 2 weeks. Unfortunately, over time, these structures deteriorate. An older person has half the buds than a younger one, which is why it sometimes costs older people more to identify certain flavors. Smokers have the same problem because exposure to tobacco smoke decreases the proportion of these cells.
What are taste buds?
As we mentioned in the previous lines, taste buds are the sensory cells present in the taste buds responsible for transmitting the signals that result in the taste itself. Each taste bud is formed by the association of about 50 to 100 cells, called taste receptor cells (TCRs). In mammals, the taste buds are widely distributed over the tongue, soft palate, and oropharynx.
These curious buttons have an ovoid shape, between 50 and 60 microns high and 30 to 70 high. In each taste button we find 3 types of cells, the characteristics and functions are different. We present them to you in the following list:
- Type I: they are thin and dense, with a supporting function. They also function as glia and have ionic currents involved in the transduction of salty taste (60% of the total).
- Type II: clear and fine, with small hairs at its apical end. They have transducing receptors for sweet, bitter, and umami flavors (30% of total).
- Type III: similar to the above, but with synaptic vesicles in the central area. They involve the transduction of sour taste (10% of the total).
In general, two possible neural models are described to explain how taste buds work. To simplify matters, we will say that the first postulates that a cell receiving taste by itself detects a single basic taste mode and is innervated by individual nerve fibers which transmit signals from this single mode (one speaks of marked line). Once these cells are stimulated, information is sent as a potential action to the brain.
In the other model, known as the computational model, individual taste receptor cells detect one or more taste modalities, and fibers transmit signals from several modalities simultaneously. It is therefore a more complex activity complex than in the previous case.
Types of taste buds
Once we have explored the world of the taste buds, we can come back to the taste buds. It’s time to clarify that there are 4 types of them, and we’ll explain them briefly below.
1. Fungiform papillae
They are so named because they are mushroom shaped, no more and no less. They are rare in many animals and they are located at the end of the tongue. It is interesting to know that they are found not only in humans, but also in other mammals. They are much more numerous in carnivores and reduced in appearance in cattle and horses.
Composed of a head and a pedicel, these types of papillae are very visible, due to the reddish color given to them by the blood vessels that supply them. These types of taste buds are stimulated much more in old age and the early stages of development, such as they are mainly specialized in the treatment of sweet taste. According to various sources, this type is the most represented taste nature in the human species.
2. Chalciform papillae
Also known as circumvalent papillae, they are a large and underrepresented type of papillae, but of vital importance: they detect bitter taste. These are found in a number of 11s in a V-shaped arrangement on the back of the tongue, near the tonsils, and can be clearly seen as “bumps” or bundles.
In addition to their detection of bitter flavors, they also exhibit a number of minor salivary glands that aid the digestion process. We say that these are the most important taste buds because they detect the bitter taste, which in many cases can be dangerous ingestion. In addition, being 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 parallel series that go obliquely from the middle groove of the tongue to the edges of the same. They are the most abundant type in the language but, oddly enough, their function is not to interpret flavors.
The filiform papillae act as a cover for the tongue. They give it a rough and abrasive structure, which helps us clean our mouths, swallow and speak. In simpler terms, they act as physiological “grabbers” in multiple oral processes. Its thermal and tactile function is especially stimulated during the adult period of the individual.
4. Leafy taste buds
Leaves or foliate papillae they appear in the form of short vertical folds, present in parallel on either side of the back of the tongue. These appear in the form of symmetrical ridges, numbered 4 to 5 times, depending on the individual. Its receptors capture salty flavors.
A glimpse of the language
Let’s do a little final review, as we have introduced a lot of terms that require a “mind map”. Imagine your own tongue in the mirror. At the tip, the fungiform papillae are agglutinated, responsible for interpreting the sweet flavors.
If you step back, near the bell, you will find 11 large taste buds arranged in a V-shape, responsible for treating bitter taste and promoting vomitingor when the ingested element could be harmful to the organism.
On the sides and looking at the base of the tongue, we will find a series of folds in which the leafy papillae are located. These are responsible for capturing the salty flavors.
However, as we saw above, each taste button contains several cells responsible for identifying different types of flavors and, depending on the computer model, each button would send information about more than one taste of the relevant nerve ending. In this case, the “card taste “described here would be of little use to us, since it is postulated that each papilla may contain all or part of the cells which interpret certain flavors. In any case, the lingual map helps to understand the arrangement of the types of papillae and we gives a general idea of their function.
As you may have read these lines, the world of taste buds has a lot to talk about. There are some differences and debates, because the truth is that even today we do not know some of the peculiarities of the sense of taste..
However, it is clear that this has been essential for the development and permanence of the human species over time. Taste buds have allowed us to distinguish these dangerous foods from nutritious foods, allowing us to develop physically through adequate calorie intake. In the human body, every cell counts.
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- Hernández Calderón, ML and Díaz Barriga Arceo, S. (2020). The biochemistry and physiology of taste. Journal of Biochemical Education, 38 (4), 100-104.
- Oral, IC and Pharynx, I. Physiology of taste
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