Chapter5

TheIntegumentarySystemSkinanditsaccessorystructuresstructurefunctiongrowthandrepair1第1頁GeneralAnatomyAlargeorgancomposedofall4tissuetypes22squarefeet1-2mmthickWeight10lbs.2第2頁Overview3MajorlayersofskinEpidermisisepithelialtissueonlyDermisislayerofconnectivetissue,nerve&muscleHypodermis(subcutaneous)islayerofadipose&areolartissues3第3頁OverviewofEpidermisStratifiedsquamousepitheliumContainsnobloodvessels4typesofcells5distinctstrata(layers)ofcells4第4頁CelltypesoftheEpidermisKeratinocytes--90%producekeratinMelanocytes-----8%producesmelaninpigmentmelanintransferredtoothercellswithlongcellprocessesLangerhancellsfrombonemarrowprovideimmunityMerkelcellsindeepestlayerformtouchreceptorwithsensoryneuron5第5頁Layers(Strata)oftheEpidermisStratumcorneumStratumlucidumStratumgranulosumStratumspinosumStratumbasale6第6頁StratumBasaleDeepestsinglelayerofcellsCombinationofmerkelcells,melanocytes,keratinocytes&stemcellsthatdividerepeatedlyCellsattachedtoeachother&tobasementmembranebydesmosomes&hemidesmosomes7第7頁StratumSpinosum8to10celllayersheldtogetherbydesmosomesDuringslidepreparation,cellsshrinkandlookspinyMelanintakeninbyphagocytosisfromnearbymelanocytes8第8頁StratumGranulosum3-5layersofflatdyingcellsShownucleardegenerationContaindark-stainingkeratohyalingranulesContainlamellargranulesthatreleaselipidthatrepelswater9第9頁StratumLucidum

Seeninthickskinonpalms&solesoffeetThreetofivelayersofclear,flat,deadcellsContainsprecursorofkeratin10第10頁StratumCorneum25to30layersofflatdeadcellsfilledwithkeratinandsurroundedbylipidsContinuouslyshedBarriertolight,heat,water,chemicals&bacteriaFrictionstimulatescallusformation11第11頁Keratinization&EpidermalGrowthStemcellsdividetoproducekeratinocytesAskeratinocytesarepusheduptowardsthesurface,theyfillwithkeratin4weekjourneyunlessouterlayersremovedinabrasionHormoneEGF(epidermalgrowthfactor)canspeedupprocessPsoriasis=chronicskindisordercellsshedin7to10daysasflakysilveryscalesabnormalkeratinproduced12第12頁SkinGraftsNewskincannotregenerateifstratumbasaleanditsstemcellsaredestroyedSkingraftiscoveringofwoundwithpieceofhealthyskinautograftfromselfisograftfromtwinautologousskintransplantationofpatientsskingrowninculture13第13頁DermisConnectivetissuelayercomposedofcollagen&elasticfibers,fibroblasts,macrophages&fatcellsContainshairfollicles,glands,nerves&bloodvesselsMajorregionsofdermispapillaryregionreticularregion14第14頁PapillaryRegionTop20%ofdermisComposedoflooseCT&elasticfibersFingerlikeprojectionscalleddermalpapillaeFunctionsanchorsepidermistodermiscontainscapillariesthatfeedepidermiscontainsMeissner’scorpuscles(touch)&freenerveendings(painandtemperature)15第15頁

ReticularRegionDenseirregularconnectivetissueContainsinterlacingcollagenandelasticfibersPackedwithoilglands,sweatglandducts,fat&hairfolliclesProvidesstrength,extensibility&elasticitytoskinstretchmarksaredermaltearsfromextremestretchingEpidermalridgesforminfetusasepidermisconformstodermalpapillaefingerprintsareleftbysweatglandsopenonridgesincreasegripofhand16第16頁SkinColorPigments(1)Melaninproducedinepidermisbymelanocytessamenumberofmelanocytesineveryone,butdifferingamountsofpigmentproducedresultsvaryfromyellowtotantoblackcolormelanocytesconverttyrosinetomelaninUVinsunlightincreasesmelaninproductionClinicalobservationsfrecklesorliverspots=melanocytesinapatchalbinism=inheritedlackoftyrosinase;nopigmentvitiligo=autoimmunelossofmelanocytesinareasoftheskinproduceswhitepatches17第17頁SkinColorPigments(2)Caroteneindermisyellow-orangepigment(precursorofvitaminA)foundinstratumcorneum&dermisHemoglobinred,oxygen-carryingpigmentinbloodcellsifotherpigmentsarenotpresent,epidermisistranslucentsopinknesswillbeevident18第18頁AccessoryStructuresofSkin

EpidermalderivativesCellssinkinwardduringdevelopmenttoform:hairoilglandssweatglandsnails19第19頁

StructureofHairShaft--visiblemedulla,cortex&cuticleRoot--belowthesurfaceFolliclesurroundsroot20第20頁HairRelatedStructuresArrectorpilismoothmuscleindermiscontractswithcoldorfear.formsgoosebumpsashairispulledverticallyHairrootplexusdetecthairmovement21第21頁HairColorResultofmelaninproducedinmelanocytesinhairbulbDarkhaircontainstruemelaninBlondandredhaircontainmelaninwithironandsulfuraddedGrayinghairisresultofdeclineinmelaninproductionWhitehairhasairbubblesinthemedullaryshaft22第22頁Functionsof

HairPreventsheatlossDecreasessunburnEyelasheshelpprotecteyesTouchreceptors(hairrootplexus)senseslighttouch23第23頁GlandsoftheSkinSpecializedexocrineglandsfoundindermisSebaceous(oil)glandsSudiferous(sweat)glandsCeruminous(wax)glandsMammary(milk)glands24第24頁Sebaceous(oil)glandsSecretoryportioninthedermisMostopenontohairshaftsSebumcombinationofcholesterol,proteins,fats&saltskeepshairandskinfromsoft&pliableinhibitsgrowthofbacteria&fungi(ringworm)Acnebacterialinflammationofglandssecretionsstimulatedbyhormonesatpuberty25第25頁

Sudoriferous(sweat)glandsEccrine(sweat)glandsmostareasofskinsecretoryportionindermiswithducttosurfaceregulatebodytemperaturewithperspirationApocrine(sweat)glandsarmpitandpubicregionsecretoryportionindermiswithductthatopensontohairfolliclesecretionsmoreviscousfunctionafterpuberty,“coldsweat”26第26頁

CeruminousglandsModifiedsweatglandsproducewaxysecretioninearcanalCerumincontainssecretionsofoilandwaxglandsHelpsformbarrierforentranceofforeignbodiesImpactedcerumenmayreducehearing27第27頁StructureofNailsTightlypackedkeratinizedcellsNailbodyvisibleportionpinkduetounderlyingcapillariesfreeedgeappearswhiteNailrootburiedunderskinlayerslunulaiswhiteduetothickenedstratumbasaleEponychium(cuticle)stratumcorneumlayer28第28頁NailGrowthNailmatrixbelownailrootproducesgrowthCellstransformedintotightlypackedkeratinizedcells1mmperweek29第29頁TypesofSkinThinskincoversmostofbodythinepidermis(.1to.15mm.)thatlacksstratumlucidumlacksepidermalridges,hasfewersweatglandsandsensoryreceptorsThickskinonlyonpalmsandsolesthickepidermis(.6to4.5mm.)withdistinctstratumlucidum&thickstratumcorneumlackshairfolliclesandsebaceousglands30第30頁GeneralFunctionsoftheSkinRegulationofbodytemperatureProtectionasphysicalbarrierSensoryreceptorsExcretionandabsorptionSynthesisofvitamin31第31頁SkinCancer1millioncasesdiagnosedperyear3commonformsofskincan