All our understanding of the world around us is formed indirectly through the senses. The main ones are sight, hearing, smell and touch. You can close your eyes and ears, turn off your sense of smell, but the tactile sensations will remain.
Mechanoreceptors are responsible for them, one of which is Meissner's little bodies. And although our understanding of the functioning of the organs of perception is quite broad, it is the most primitive tactile sensory receptors that still remain an unsolved mystery.
Receptors are the basis of the worldview
Receptors are specialized cells capable of receiving stimuli. For example, photoreceptors (light), chemoreceptors (taste, smell), mechanoreceptors (pressure, vibration), thermoreceptors (temperature). These cells convert stimulus energy into a signal that fires sensory neurons. The excitation mechanism is associated withthe occurrence of an action potential on cell membranes and the operation of the sodium-potassium pump. They are like encoders who translate information into the desired code. In addition, each receptor is tuned to a specific signal and its strength. They capture signals on an all-or-nothing basis, and our nervous system uses many receptors simultaneously to form a clear sensation.
Mechanoreceptors
This group of sensitive cells includes pressure receptors. They come in several types:
- Lamellar bodies (Vatera-Pacini).
- Merkel cells.
- Meissner's corpuscles.
- Krause flasks.
Tactile receptors are located in the epidermis and dermis, there are about 25 receptors of different types per 1 square centimeter of skin. But on the hands and soles of the feet, face and mucous membranes, their number increases dramatically. In addition, it is precisely the presence of Meissner's tactile bodies in the so-called G-spot that women owe the emergence of erotic susceptibility.
Vater-Pacini corpuscles
These receptors are located in the deep layers of the dermis and are responsible for the perception of pressure and vibration. They consist of a bulb (flask), inside which sensory nerve fibers are branched. The flask is covered with a capsule with liquid and myofibrils. Fluid pressure is transmitted to unmyelinated nerve endings.
Merkel cells
These are sensitive cells located at the base of the hair follicle and in the epidermis of the skin (most of all on the palms of the hands). In addition to tactilesensitivity, they are also considered neuroendocrine. It has been proven that in embryogenesis they secrete substances that stimulate the growth of nerve fibers and skin derivatives.
Meissner's corpuscles
In the tops of the papillae of the dermis are these clusters of sensitive cells. What are Meissner bodies? This is a group of tactile cells, the flat parts of which form perpendicular peculiar plates. All this is enclosed in a capsule, where the nerve fiber enters and branches. All components of the Meissner body are interconnected by myofibrils. The slightest pressure on the epidermis is transmitted to the nerve endings.
Krause flasks
Spherical formations, which are especially numerous on the oral mucosa. Their susceptibility is tuned to cold and pressure perception. They are similar in structure to Meissner's bodies and have so far been little studied. The perception of the notorious G-spot in the upper third of the vagina of women is also associated with the accumulation of these receptors.
Who is responsible for what
As already mentioned, tactile sensations and their occurrence are still fraught with many mysteries. So far, only some functions of the mechanoreceptors of our skin have been established empirically. The function of Meissner bodies is the perception of subtle sensitivity, Vater-Pacini is a rough and single assessment of the force of pressure, Krause flasks are cold sensations and pressure assessment. And to Merkel cells, we owe the feeling of being patted on the head.
How it works
Sensitivity of tactile analyzers is high only to changes in pressure. That is why we feelclothes and watches only at the moment of putting them on. The ability to distinguish individual touches is related to the frequency of their impacts. Fingertips are able to distinguish touches at a frequency of up to 300 per second. In addition, all receptors have their own sensitivity threshold - this is the pressure at which we feel the impact. For example, for fingertip receptors it is 3 mg/mm, and for the soles of the feet it is 250 mg/mm.
Our fingers think too
Fingerprints formed by papillary lines have presented their surprises to scientists. It has long been known that the pattern of these lines is formed in humans even in the womb and is formed by rows of skin papillae, under which there are Merkel cells and Meissner bodies. The latest research data prove that these reliefs are designed to “bounce” on uneven surfaces and turn them into acoustic vibrations that receptors can pick up. But not all of these data are transmitted by receptors to the brain, as if filtering what is important or not important. Research has confirmed that Meissner bodies process information, not just transmit it. Previously, this function belonged exclusively to the brain. Research in this area is ongoing, but now it is clear why these lines form such complex patterns.
Summation and training
Tactile analyzers are amenable to training and learning. There are many examples of this, ranging from an increase in the threshold of sensitivity in blind people to the high sensitivity of professional burglars. This is a property of a sensitive analyzerbased on the summation effect. It is based on the connection of several adjacent receptors with one sensory neuron. Thus, the signal would not cause excitation when coming from one receptor, but when coming from several receptors, excitation of the neuron is caused by the total information of receptors.
