Ultra-violet rays

Ultraviolet rays have a very largeenergy. 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 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.

Shortwave exposure provokesdenaturation 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 against the effects of UV radiation.

Average wave action contributes toactivation of the processes of vitamin formation. Thus, 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 a spiked layerskin. At the same time, 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 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. Short-wave radiation provokes erythema more quickly, leaving a slight pigmentation.

Maximum pigment-forming influencelongwave UV rays. In melanoblasts located in the basal layer of the epidermis, melanin is formed from tyrosine, adrenaline degradation products, and dioxyphenylalanine. Its (melanin) gigantic molecules prevent fragments of protein molecules destroyed by UV radiation from penetrating deep into the dermis. In addition, melanin molecules absorb infrared rays and the visible spectrum. Thus, the skin is protected from overheating and burns. In the areas of ultraviolet rays, the lymph flow and blood flow increase, the regeneration of the cover improves, and the synthesis of collagen fibers increases. With intensely erythema, chronically and acutely inflammatory processes are intensified.

UV exposure is quite wideused in cosmetology. So, in the solarium get a smooth and beautiful tan. In this case, long-wave beams are used, and filters are used for short-wave and medium-wave radiation in tanning beds.

It should be noted that excess stay onthe sun can lead to premature aging, a decrease in the elasticity of the skin. In addition, the formation of free radicals, which contribute to the development of oncology, can be activated.

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