Touch is the sense by which we recognize a certain object with our skin. Touch technically is not a single sense, but several. There are separate nerves in the skin that register whether something is cold, hot, or if we feel pressure, pain, light touch or even coarse touch. There are thousands of nerves within the human body that are specifically for the function of identifying what we feel outside the human body, and these nerves are unevenly distributed within the body. A nerve for light touch have an elongated bulb-shaped end, while those responsible for the response of cold feelings have squat bulb ends, those that register warmth have a twisted thread shape, and the nerve for deep pressure have an egg-shaped end. However pain receptors have no protective sheath. Sensory nerves are evenly distributed over the whole body, each 6.5 square cm of skin would have approximately around 8 cold receptors, 50 for heat, 100 for touch, and about 800 for pain. Sensitivity of any given spot on the body depends on the part and how thickly receptors of any kind are clustered in that given spot, and localization of a particular sensation depends on the concentration of the necessary nerve endings in that given area. Sensations of cold and heat are widely diffused within the body, while pressure, light touch and pain sensations can be quite localized. Touch is one of the five senses, along with taste, smell, hearing and sight. It is the sense responsible for the perception of stimuli affecting the outer surface of the human body, through which the brain receives information on the surrounding environment. The main organ for the sensation of touch is the skin.
What is touch?
Tact is therefore the sense which enables the recognition of certain physical characteristics of the object, such as hardness and shape, which come in contact with the outer surface of the body (skin and mucous membranes that communicate with the outside).
The transmission of the sense of touch from the outer surface of the body to the brain is made possible by the complex mechanisms that originate in highly specialized cells for this purpose, these are the receptors of touch. The latter are tiny organs each with its own characteristics and capabilities; Meissner corpuscles, Merkel discs, Pacinian corpuscles, corpuscles of Golgi-Mazzoni. The receptors of touch are present with very high density in the skin of the face and upper limbs, giving in these particular areas of the body sensitivity, while in the lower limbs and the spine they are present in minor amounts.
The tactile sensation may experience different types of alterations, both quantitative and qualitative. In the first group, they are distinguished by hypoesthesia (partial or total reduction of sensitivity in its various forms) and hyperesthesia (increased sensitivity to normal nerve impulses). Atmosphere is in the second group of dysesthesia, a disorder characterized by the deterioration of touch. These alterations are usually dependent disorders in the peripheral nerves or organs of the central nervous system which in turn are triggered by traumatic, viral, metabolic or inflammatory causes.
What function does touch serve?
The sense of touch is the member of the recognition of certain physical characteristics of the objects (hardness, shape) that come in contact with the outer surface of the body, allowing the brain to receive information on our surrondings.
