Slide 1Intro to the IntegumentThe IntegumentIntegument FunctionsThe EpidermisEpidermal StrataLayers of the StrataCells of the Stratum CorneumThick and Thin SkinEpidermal Variation: Skin ColorAbnormal Skin ColorsEpidermal Variation: Skin MarkingsFingerprintsThe DermisDermisThe Papillary LayerThe Reticular LayerLines of CleavageLines of CleavageInnervationBlood SupplyThe HypodermisHypodermis (Subcutaneous Layer)Slide 24Epidermal DerivativesNailsNailsStructure of a HairHairOther Hair StructureSlide 31Structure of a HairFunctions of Hair3 Types of HairSkin Exocrine GlandsSweat GlandsMerocrine Sweat GlandsApocrine Sweat GlandsSebaceous GlandsSlide 40Integumentary SystemIntro to the IntegumentIntegument = skinlargest organ (7% to 8% of body weight)Thickness ranges between 1.5 and 4mm or moretwo layersepidermis: superficial layer of stratified squamous epitheliumdermis: deeper layer of areolar and dense irregular connective tissueshypodermis (not part of the skin) lies under dermis, mostly adipose connective tissueThe IntegumentFigure 5.1Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Hair shaftSweat poreEpidermal ridgeDermal papillaArrector pili muscleSebaceous (oil) glandSweat gland ductMerocrine sweat glandSensory nerve fiberApocrine sweat glandVeinArteryAdipose connective tissueAreolarconnective tissueSubcutaneouslayerSensoryreceptorsHair follicleEpidermisDermisPapillarylayerReticularlayerIntegument FunctionsProtectionPrevention of H2O lossTemperature regulationMetabolic regulation through Vit. D productionImmune defenseSensory receptionExcretion/SecretionThe EpidermisMost superficial layerAvascularKeratinized stratified squamous epitheliumkeratin is a water-insoluble protein4 to 5 layers (strata) of distinct cell typesEpidermal StrataEpidermis has several layersFrom superficial to deep:stratum corneumstratum lucidum (found only in thick skin)stratum granulosumstratum spinosumstratum basaleLayers of the StrataFigure 5.2Cells of the Stratum CorneumFigure 5.3Thick and Thin SkinAround body skin averages 1-2 mmClassified as thick or thin based upon number of layers of the epidermisThin skin covers most of the body, but only has 4 layersLacks stratum lucidumThick skin is on the palms of the hand, soles of the feet and corresponding parts of the fingers and toes. Contains sweat glands but no hair follicles or sebaceous glandsEpidermal Variation: Skin ColorSkin color is determined by three pigments:hemoglobin: blood pigment; causes light complexions to look pink (or blue)melanin: pigment produced by melanocytes; increases in people exposed to more UV lightcarotene: yellow-orange pigment from food that builds up in the skinAbnormal Skin ColorsEpidermal Variation: Skin MarkingsNevus: localized overgrowth of melanocytesa.k.a. moleHemangioma: proliferation of blood vesselsmay disappear (strawberry) in childhood or may persist (port-wine) through adulthoodFriction ridges: folds of epidermis/dermis on fingers, palms, soles, and toes for graspingcause us to leave fingerprintsFingerprints Figure 5.5The DermisLies deep to the epidermisTwo layers of connective tissues:Papillary: superficialContains sensory receptors and gives nutrients to the epidermis Reticular: deepermainly collagen fibers – gives dense network to:blood vessels, glands, hair follicles, nail roots, sensory nerve endings, and smooth muscleDermisFigure 5.6The Papillary LayerDirectly below epidermisdermal papillae-projections of dermis towards dermisepidermal ridges –deep projections of epidermisBoth interlock, increasing the surface area between epidermis and dermisdermal papillae contain capillaries that supply nutrients to the avascular epidermal cellsThe Reticular LayerForms majority of the dermisComprised mainly of dense irregular connective tissue with large bundles of collagen fibers, blood vessels, glands, hair follicles, and nervescollagen bundles help connect dermis to underlying hypodermisLines of CleavageLines in the deep dermis formed by the orientation of collagen bundlesimportance to surgeons: incisions across these lines heal more slowly than incisions alo ng the linesLines of CleavageFigure 5.7Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.An incision parallelto cleavage lines is morelikely to heal quickly andnot gape open.An incisionperpendicular tocleavage lines maygape and delay healing.InnervationNerve fibers are present in dermisFunctions:tactile (touch) receptorscontrol blood flowcontrol glandular secretionBlood SupplyEpidermis: avascularDermis: contains blood vesselsimportant in controlling body temperaturevasoconstriction: narrowing blood vessels preserves core body heatvasodilation: widening blood vessels releases body heat, lowering body temperatureThe HypodermisA.K.A. subcutaneous layerdeep to, not really part of, the integumentadipose and connective tissuesFunctions:padding protects underlying structuresstores energythermal insulationHypodermis (Subcutaneous Layer)Figure 5.6Epidermal DerivativesStructures that grow from the epidermis:NailsHairsGlandsHypodermas not part of integuityNailsDerived from the stratum corneum of the epidermisCells densely packed together filled with parallel fibers of hard keratinThe nail plate has a whitish free edge, a pinkish nail body, and a nail rootThe nail body covers a layer of epidermis called the nail bedThe nail bed appears pink because of the underlying capillariesNailsProtective structures on digitsPartsnail body: flat keratinized cells protecting digitnail bed: live epidermal cells under nail bodynail root: region hidden by cuticlenail matrix: thickened growing part of the nail bedStructure of a HairFigure 5.9Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.(a)RootShaft(beyond epidermis)Sebaceous(oil) glandHair follicleArrectorpili muscleMatrixHair bulbMelanocyteHair papillaHairColumns of keratinocytes growing from follicles deep in dermis or hypodermisRegions of a hair from deep to surface:Hair bulb – hair origination with blood and nerve supply Hair root – hair found within the follicle (under the skin)Hair shaft – hair that extends