Ultra-violet rays

Ultraviolet rays have very high energy. In this connection, significant changes occur in the process of their absorption in molecular and atomic structures. Absorbed energy, which was allocated by ultraviolet rays, can be used in the rupture of weak bonds of protein molecules. This process is called photolysis. Its course is accompanied by the release of active substances under the influence of medium-wave ultraviolet irradiation.

Short-wave action provokes denaturation of protein polymers, which, losing their activity, precipitate. Ultraviolet rays have a special effect on DNA molecules. In the process of influence there is a violation of DNA doubling and cell division. Along with this, ultraviolet rays cause oxidative destruction in protein structures. This leads to cell death. But the damaged nuclei have the ability to recover (dark repair). This is possible under the influence of long-wave UV radiation and the energy of visible light. Certain enzymes participate in these processes.

Dark and photoreactive reparation belong to the category of protective-adaptive reactions. They are inherent in nature in the human body and provide protection from the effects of UV radiation.

The medium-wave effect promotes activation of the processes of vitamin formation. So, ultraviolet rays transform the provitamins contained in the skin into vitamin D. Penetrating only one-tenth of a millimeter, the effect provides the formation of a large amount of energy in comparison with other electromagnetic oscillations of the infrared and visible spectrum.

Photolysis and denaturation take place in the spine-like layer of the skin. Along with this, histamine, acetylcholine, biogenic amines are released. These compounds provoke the development of erythema. It occurs after 2-8 hours. Protein decomposition products contribute to vasodilation, migration of leukocytes, and swelling of the skin. All these phenomena are complicated by irritation of the skin receptors, receptors of internal organs, with the appearance of neuroreflex reactions. The products of disintegration diverge along the bloodstream, exerting a humoral effect. Ultraviolet irradiation of the medium-wave spectrum provokes an aseptic inflammatory reaction in the skin. By the second day it reaches its maximum. On the seventh-ninth day the inflammatory reaction passes, instead of it there is a sunburn. Shortwave radiation quickly provokes erythema, leaving a slight pigmentation.

The maximum pigment-forming effect is produced by long-wave UV rays. Melanin forms in the melanoblasts located in the basal layer of the epidermis, from tyrosine, adrenaline decomposition products and dioxyphenylalanine. Its (melanin) giant molecules prevent the ingress of protein fragments destroyed by UV radiation into the dermis of the dermis. In addition, melanin molecules absorb infrared rays and the visible spectrum. Thus, the skin is protected from overheating and burns. In areas of influence of ultraviolet rays, lymph flow and blood flow increase, regeneration of the cover improves, synthesis of collagen fibers increases. With intensively flowing erythema, chronically and acutely inflammatory processes increase.

Ultraviolet exposure is widely used in cosmetology. So, in the solarium receive a smooth and beautiful tan. In this case, long-wave beams are used, and short-wave and medium-wave radiation in solariums are filters.

It should be noted that excessive exposure to the sun can lead to premature aging, a decrease in the elasticity of the skin. In addition, the process of formation of free radicals, which contribute to the onset of oncology, can be activated.

To determine the boundary between the "harmful" and "useful" sun, the ultraviolet index is used. This parameter signals the level of radiation on the Earth.