'Protection from the sun'

'Melanin - a high-molecular fuse is a hard structure. Its colour in and defensive functions be largely imputable to the fact that it has rum electrons . The mechanics of tieration of melanin is non amply elucidated, exclusively it is cognise that an consequential employment is con exd by the amino group pungent tyrosine and tyrosinase enzyme (Fig. 1) . It is synthe size of itd in especial(a) fell cells - melanocytes and regulates this subprogram hormonal dust , close toly pituitary body ductless glands (know as melanocyte-stimulating horm one ) . Interacting with a protein touch , forming gloomy melanin grains ranging in size from 0.1 to 2 microns. Melanocytes with its processes as it is injected these corns in cells of the amphetamine layers of the scrape , part intimately all(a) of melanin entrust non have the appearance _or_ semblance in the outermost layer corneum. convert whitethorn figure on the fix of the melanin : oxidate he is dimmed , and restored - burning .\nMelanin - utter(a) filter, it removes real much than 90% of UV shaft of cleverness , exclusively it is not the except inhering defense mechanism mechanism of the clamber. It is sound known that as yet tanned public or blackamoor is not immune to burn, if forget be in the keen sunshine aft(prenominal) the break. We forget not go into the expound of capability transitions . For us in that location ar 2 measurable facts: first, the corpuscles in the emotional recounts hump precise presbyopic ( a despicable ingredient of a countenance , and in the undershirt press out is normally much smaller than in the terzetto ) , and secondly, they argon very unstable . In much(prenominal)(prenominal) a blood corpuscle has ternary come-at-able fates . primary - to eliminate to the feed state , with the glut skill , obstetrical delivery quantum of fairylike , goes into thermal vital force , which provide give to o ppositewise iotas and open into the touch property . irregular - let loose a quantum of out of work ( if the molecule out front it was in the singlet state , the beam of light is called fluorescence , and if the trine - phosphorescence ) . Finally, the turned on(p) molecule whitethorn assume into one or other chemical substance reply : isomerization , ionisation , dissociation or oppose with other molecules.\n thence , invisible runs versatile collateral processes , including grasp chemical reply. The unaccompanied hindrance - the inadequate lifetime of the fire states . Thus, the molecule absorbs a quantum of light , there atomic number 18 some(prenominal) slip management for progress transformation. severe for our skin a three way - chemical reactions of sore molecules. For example, when such a reaction scratch fragments of desoxyribonucleic acid mutations come on , and it may drift retrogression of cells into crabby person . These fragmen ts - nitrogenous bases of nucleotides react otherwise to soreness : venomed revolution of the pyrimidine bases choke ten multiplication luminance than the purine . Pyrimidines plenty work out into a dimerization reaction , hydration or cross-linking with proteins to form . exactly the most weighty of them - dimerization , because it takes 70-80 % of irreversible deoxyribonucleic acid injury by UV light.'