7 junio, 2024

Sense of touch: what it is, parts, how it works, functions

What is the sense of touch?

He sense of touch It is one of the five senses that allow us to relate to our environment and perceive qualities of our environment. Through it, we can feel characteristics such as temperature, hardness, pressure, or texture. Some experts also include the perception of pain.

The most important sensory organ for the sense of touch is the skin. In it, we can find different types of nerve receptors, which translate the information received from the outside into impulses that the brain can understand and interpret. On the other hand, it is possible to find some of these receptors in other body organs.

The sense of touch is vital to our survival. Some scientists believe that without its functions, it would be impossible for human beings to survive, contrary to what happens with sight, hearing, taste or smell. However, researching about him is quite complicated, so we don’t have as much data as one might expect.

The main difficulty in investigating touch is that its main sensory organ (the skin) spans the entire body, rather than there being a single location where the receptors are isolated, as is the case with the other senses. .

Parts (organs)

The main element related to touch is the skin, that membrane that covers the entire body. Therefore, it is the largest organ, and one of the most important. All existing tactile receptors are concentrated in the skin.

On the other hand, today we also know that there are touch receptors in other areas of the body. These are not as abundant as those of the skin, but they fulfill the fundamental function of informing us about the state of our internal organs.

Fur

The skin is the organ that covers our entire body externally. Among its functions are protection against external agents, such as microbes, maintaining the temperature of our body, and the perception of tactile stimuli and their transformation into impulses that the brain can interpret.

The skin is made up of three layers: epidermis, dermis and subcutis. The epidermis is the outermost, and is approximately two-tenths of a millimeter thick. It is made up of a large number of layers of flat epithelial tissue, and it produces melanin, a substance that gives our skin its color.

Then there is the dermis. It is a more elastic layer than the first, due to the collagen fibers it incorporates. In it we can find a large number of blood vessels and components of the lymphatic system. In this layer are also all the skin glands (scent, sweat and sebaceous).

Likewise, in the dermis are the nerve endings and the receptors that allow us to perceive tactile sensations.

Finally, the subcutis is a layer made up of connective tissue. Its main function is to maintain body temperature and serve as an energy store, which is why adipose tissue also accumulates in this area. Depending on the area of ​​the body, the accumulation of fat will be greater or less.

Types of receptors in the skin

In the dermis we can find different receptors that allow us to receive tactile information and convert it into electrical signals that the brain will interpret.

free nerve endings

The simplest tactile receptors are simple nerve endings that end in the dermis and help us perceive sensations such as touch, temperature, itching, and pain. These are neurons whose dendrites end in the middle layer of the skin, as well as in the connective tissue below the dermis.

Free nerve endings are the most abundant tactile receptors in the entire body, and the ones that help us perceive most of the sensations related to this sense.

Pacinian corpuscles

These receptors are also found in the dermis and in the connective tissue below the skin. However, they can also be found in some internal structures, such as viscera or bones. These are large, oval-shaped receivers.

Pacinian corpuscles are made up of a single nerve cell, covered by a capsule. Its main function is to allow us to perceive stimuli related to touch and pressure.

Meissner corpuscles

Meissner’s corpuscles are very sensitive receptors to the different sensations related to touch. They are found in very high concentrations in the most perceptive areas of our body, such as the tip of the tongue or the fingertips.

These receptors are made up of a capsule inside which are several cells superimposed one on top of the other.

Ruffini’s corpuscles

Ruffini’s corpuscles are located both in the dermis and in the connective tissue that we have under the skin. They are formed by neurons with many ramifications, covered by a capsule. They are mainly in charge of detecting temperature variations (specifically, heat) and identifying continuous deformations of the skin.

Krause’s corpuscles

It was previously thought that these skin receptors, located in the dermis, had the main function of allowing us to detect cold. Currently, its function is not known.

They have a similar shape to those of Pacini, but smaller, being formed by a nerve ending with many ramifications, which in turn is covered by a club-shaped capsule. They are located in the submucosal tissues of the mouth, nose, genitals and eyes.

Merkel discs

They are a set of mechanoreceptors responsible for the perception of textures and pressure. They are between the mucosa and the skin, they are one of the most sensitive and acute receptors, capable of obtaining extremely detailed information from the stimuli they receive.

receptors in other parts of the body

Some of the receptors for the sense of touch are not only located in the skin, they are also in other areas of the body. Thus, organs such as muscles or viscera have certain nerve endings intended to provide information about the internal state of the organism.

nociceptors

Some researchers consider that the detection of pain is also part of the functions of the sense of touch. Due to this, to the receptors that we have already seen, one last type should be added: the nociceptors.

These tactile receptors are located throughout the dermis, as well as in some internal organs. Its main function is to perceive harmful stimuli, and translate them into nerve impulses that are transmitted to the brain. Once there, he interprets them as pain.

How does the sense of touch work?

The functioning of the sense of touch is very similar to that of the other four main senses. Tactile receptors (mechanoreceptors, thermoreceptors, and nociceptors) are distributed throughout the skin, like a network, and detect stimuli related to factors such as pressure, texture, temperature, or pain. These stimuli can come from both outside the body and from within the organism.

Once a receptor has detected a stimulus to which it is sensitive, it sends a signal to the brain via afferent neurons. These connect the sensory organs with the central nervous system through the spinal cord.

The signals collected by the sense organs are then interpreted in the corresponding areas of the brain. The processing of tactile stimuli occupies a large percentage of the brain surface, because the information collected by this sense is essential for survival.

Finally, the brain sends a response through the efferent neurons to the corresponding effector organs, depending on the type of stimulus that has been received and what it implies for the organism.

functions

The sense of touch fulfills a series of fundamental functions for our survival.

It allows us to know where the limits of our body are, by perceiving sensations such as pressure, heat or pain when coming into contact with objects external to our body.
It allows us to know if there is any kind of problem within our body, especially in our internal organs, muscles or bones. This is why we have certain pain receptors in our viscera and other internal tissues.
It also helps to perceive external dangers, such as objects that can harm us in some way. Thanks to this sense, we can react to threats and avoid suffering very negative consequences.
It allows us to collect valuable information about our environment and about the objects and living beings with which we interact.

References

Sense organs: touch. Retrieved from abc.com.py.
Organ of the sense of touch. Retrieved from academia.edu.

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