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1、皮肤的结构及护理（Structureandnursingofskin）Theskinisthelargestorganofthehumanbody,thetotalweightofthebodyweightof5%to15%,thetotalareaof1.5to2squaremeters,thethicknessvariesfrompersontoperson,orfromplacetoplace,0.5to4millimeters.Theskincoversthewholebody,whichpreventsthetissuesandorgansofthebodyfro
2、mphysical,mechanical,chemical,andpathogenicmicrobialinvasion.Theskinhastwobarriers:ontheonehand,itpreventslossofwater,electrolytesandothersubstancesinthebody;ontheotherhand,itpreventstheinvasionofharmfulsubstancesfromtheoutside.Maintainingthestabilityofthehumanbodyenvironment,playsanimport
3、antprotectivefunctioninphysiology,andtheskinalsoparticipatesinthemetabolismprocessofthehumanbody.Thereareseveralcolorsofskin(white,yellow,red,brown,black,etc.),mainlyduetorace,ageandlocationvary.Theskiniscomposedofepidermis,dermisandsubcutaneoustissue,andcontainsappendages(sweatglands,seba
4、ceousglands,nails,toenails),aswellasbloodvessels,lymphatics,nervesandmuscles.Theepidermisistheoutermostlayeroftheskin,withanaveragethicknessof0.2mm.Accordingtothedifferentstagesofdevelopmentandmorphologicalcharacteristicsofthecells,theepidermiscanbedividedinto5layers.1.stratumcorneum:compo
5、sedofseverallayersofkeratinocytes,containingkeratin.Itcanresistfriction,preventleakageandchemicalimmersionfluid.Strongkeratinwaterabsorptioncapacity,watercontentisgenerallynotlessthan10%,inordertomaintaintheskinsoft,iflessthanthisvalue,theskinisdry,chappedorscalyappearance.Becauseofdiffere
6、ntparts,thethicknessdifferenceisverylarge,suchastheeyelids,foreskin,forehead,abdomen,andotherpartsofthecubitalfossaisthin,metacarpalandmetatarsalthickparts.Thereisnonucleusinthestratumcorneum.Ifthereisanuclearremnant,itiscalledkeratosis.2.transparentlayer:composedof2-3layersofflatclearcell
7、sthatcontainthenucleus.Itcanpreventthepermeationofwater,electrolyteandchemicalsubstances,soitisalsocalledbarrierbelt.Thislayerismostobviousatthepalmsandsoles.3.granularlayer:composedof2-4layersofspindlespindlecells,containingalargenumberofbasophilictransparent
