Our whole idea 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 the smell, but the tactile sensations will remain.
Mechanoreceptors are responsible for them, one of which are Meissner bodies. And although our ideas about the functioning of the sensory organs are quite wide, it is precisely the most primitive tactile sensitive receptors that remain an unsolved mystery.
Receptors - the basis of worldview
Receptors are specialized cells capable of perceiving stimuli. For example, photoreceptors (light), chemoreceptors (taste, smell), mechanoreceptors (pressure, vibration), thermoreceptors (temperature). These cells convert the stimulus energy into a signal that excites sensory neurons. The excitation mechanism is associated with the emergence of an action potential on the cell membranes and the operation of the sodium-potassium pump. They are like encoders that translate information into the right code. In addition, each receptor is tuned to a specific signal and its strength. They capture signals on the principle of "all or nothing," and to form a clear sensation, our nervous system simultaneously uses many receptors.
Mechanoreceptors
This group of sensitive cells includes pressure receptors. They are of several types:
- Plate bodies (Fatera Pacini).
- Merkel cells.
- Meissner Taurus.
- Flasks Krause.
Tactile receptors are located in the epidermis and dermis, about 25 receptors of various 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 the tactile bodies of Meissner at the so-called G point that women are obliged to the emergence of erotic susceptibility.
Taurus Fatera Pacini
These receptors are located in the deeper layers of the dermis and are responsible for the perception of pressure and vibration. They consist of a bulb (bulb), inside of which sensitive nerve fibers are branched. The flask is covered with a capsule with liquid and myofibrils. Pressure is transmitted through fluid to the myelin-free 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 tactile sensitivity, they are also considered neuroendocrine. It is proved that in embryogenesis it is they that secrete substances that stimulate the growth of nerve fibers and skin derivatives.
Meisner Taurus
At the tips 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 myofibril fibers. The slightest pressure on the epidermis is transmitted to the nerve endings.
Flasks Krause
Spherical formations, which are especially numerous on the oral mucosa. Their susceptibility is tuned to cold and pressure perception. The structure is similar to Meisner's bodies and has not been studied much. 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 conceal many more mysteries. Empirically, so far only certain functions of the mechanoreceptors of our skin have been established. The function of Meisner's bodies is the perception of subtle sensitivity, Fater-Pacini - a rough and one-time assessment of the pressure force, Krause flasks - cold sensations and pressure assessment. And we owe Merkel cells to the sensations of stroking the head.
How it works
The sensitivity of tactile analyzers is high only to pressure changes. That is why we only feel clothes and watches when they are put on. The ability to distinguish between individual touches is related to the frequency of their effects. The fingertips are capable of distinguishing touches with a frequency of up to 300 per second. In addition, all receptors have their own threshold of sensitivity - this is the pressure at which we feel the impact. For example, for the fingertips, this is 3 mg / mm, and for the soles of the feet - 250 mg / mm.
Our fingers think too
Fingerprints formed by papillary lines presented 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. Recent research evidence suggests that these reliefs are designed to “bounce” on surface irregularities and turn them into acoustic vibrations that can pick up receptors. But not all of these data are transmitted to the brain by the receptors, as if filtering the important is not important. Studies have 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 lend themselves to training and learning. There are many examples of this, ranging from raising the threshold of sensitivity in blind people to high sensitivity of professional crackers. This property of a sensitive analyzer is based on the effect of summation. It is based on the connection of several adjacent receptors with one sensory neuron. Thus, a signal would not cause excitation upon receipt from a single receptor, but upon receipt from several, the excitation of a neuron is caused by the total information of the receptors.