INTEGUMENTARYSYSTEM&GLANDS

HumanAnatomyUnit1

InAnatomyToday

IntegumentarySystem

• Components– Skin– integument• Dermisandepidermis• Supportedbyhypodermis

– Accessorystructures• Hair• Nails• Cutaneousglands

Functions• Protectionfromtraumaandinfection– Sensoryfunctions– Physicalbarrier– Immunecells

• Preventsdesiccationandwaterimbalance– Keratinandwaterproofing

• SynthesisofVitaminD– ImportantforuptakeofCa2+

• Regulationoftemperature– Insulation– Vasoconstrictionandvasodilation

ThickSkinvs.ThinSkin

• Thickskin– Palmsandsoles– Epidermis=4-6mmthick– 5layers– Hassweatglands– Nohairfollicles,sebaceousglands,arrectorpilimuscles

• Thinskin– Restofbody– Epidermis=.75-1.50mmthick

– Thinstratumcorneum– Stratumlucidumandgranulosumnotpresentindistinctlayers

SkinHistology

ThickSkin ThinSkin

StratumCorneum

• Upto30layersofdeadkeratinizedcells

• Waterresistant

StratumLucidum

• Onlyfoundinthickskin• Cellsareanucleateandlackorganelles

StratumGranulosum

• 3-5layersofflattenedkeratinocytes

• Containkeratohyalinegranules

StratumSpinosum

• Thickeststratuminthinskin

• Cellsflattenandfillwithkeratinasmovetothetop

• Connectedbydesmosomes=confersaspinyappearance

StratumBasale• Singlelayerofcells

restingonbasementmembrane– Stemcells– Keratinocytes– Merkelcells– Melanocytes

• Germinative layer• Mitosis

• Givesrisetocellsthataremovedtotheupperlayers

EpidermalCellTypes

• Keratinocytes• Nonkeratinocytes– Melanocytes– Merkelcells

• Tactileforshapesandtextures

• Stratumbasale

– Langerhanscells• Atypeodendriticcellintheskin

• Immunecell• APC

Keratinocytes

• 90%ofepidermalcells• Undergomitosisinstratumbasaleatnight• Lifeexpectancy:20-30days• Accumulationofkeratinfilamentscausesdeathandsloughingoff

• Cytomorphosisofkeratinocytesisresponsiblefor5tissuelayersinepidermis

Melanocytes

• Foundinthestratumbasale

• Sometimesinsuperficialdermis

• Melanosomes– Granulescontainingmelanin

TheDermis

• Papillarylayer– Foldedareaimmediatelydeeptotheepidermis

– AreolarCT

• Reticularlayer– Thedeepest,largestpartofthedermis

– DenseirregularCT

TheHypodermis

• Subcutaneouslayer• Deeptothedermis• ContainsadiposeandareolarCT

• Veryvascular• Function– Bindsskintounderlyingtissues

– padding

HumanSkinPigments

• Melanin– Eumelanin(Browntoblack)– Pheomelanin(Yellowtored)– ProtectionfromUVlight

• Carotene– Yellowishpigmentfoundincertainvegetables(carrots)accumulatesinthefattypartsofthedermis

• Hemoglobin– bloodpigment,adds“redness” toskincolor

EpidermalDerivatives

• Accessorystructuresassociatedwiththeskinareactuallyderivedfromtheepidermisduringdevelopment–Hair–Nails–Glands

Hair(Pili)• Hardkeratingrowingfromhairfollicle

• Glabrousskin– Hairless– Lips,nipples,soles,palms

• Function– Insulation– Protection

• Typesofhair– Lanugo– Vellus– Terminalhair

StructureofHairandFollicleLongitudinalSection

• HairFollicle– Papilla

• Accessforbloodsupply• HairRoot

– Bulb• Epithelialcellsthatsurroundthepapilla

– Matrix• Epithelialcells,melanocytes• Celldivisionproducesthehairfiber

• Rapidlydividingcells• HairShaft

– Aboveskinsurface– Cellspackedwithkeratin

HairFolliclederivedfromepidermis

StructureofHairandFollicleCrossSection

• Medulla– Pithormarrowofhair– Mostlyairspace

• Cortex– Thickestlayer– Pigmented– Pigmentdensernearthecuticle

• Cuticle– Outermostpartofhairshaft– Hardlayerofdeadcells– Mechanicalstrength– Waterresistant

• RootSheath– Stratumbasal/spinosumof

epidermis

Hair texture = cross sectional shape Hair color = pigment granules

Nails

CutaneousGlands

• Cutaneousmeansskin• Exocrineglands– Secretoryportionsecretesaproductintoaduct– Ductalportionopenstothesurfaceofskin–

includingahairfollicle

NameofGland SecretoryProductEccrine sweatglands Sweat

Apocrinesweatglands Sweat*

Mammaryglands Milk

Sebaceousglands Sebum(oil)

Ceruminousglands Cerumen (earwax)

ClassificationbyModeofSecretion

• Merocrine Secretion– Eccrinesweatglands

• ApocrineSecretion– Apocrinesweatglands– Mammaryglands

• Holocrine Secretion– Sebaceousglands– Ceruminousglands

MerocrineSecretion

• Secretionbyexocytosiswithoutanylossofcellularcomponents

• Majorityofglandsinbody

• Examples– Eccrinesweatglands

EccrineSweatGlands

• “Regular” sweatglands• Merocrinesecretion• Mostnumeroussweatglands

• Sensitivetobodytemperatureincreases

ApocrineSecretion• Apicalsurfaceofcellis

pinchedoff• Decapitationsecretion

• Productsaremilky• Cellularproductssupport

bacterialgrowth• Secretionsareoften

associatedwithanodor

• Examples• Apocrinesweatglands• Mammaryglands

ApocrineSweatGlands• Locatedintheaxillaryandpubicregions

• Apocrinesecretion• Productissecretedintoahairfollicle

• Productisanoilycompoundthatactsasapheromone (protein,lipid,steroids)

• Sensitivetoadrenaline• Reacttoanxiety,stress,fear,sexualstimulation,painMyoepithelial cells

MammaryGlands

• Mammaryglandsareamodifiedapocrinegland

• Modifiedinfemalestosecretemilk• Milk-secretingcuboidcells

• Apocrinesecretion

Myoepithelial cells

HolocrineSecretion

• Entirecellissecretoryproduct

• Oily,waxyproduct• Examples– SebaceousGlands– Ceruminousglands

SebaceousGlandsOilGlands

– Associatedwithhairfollicles

– Holocrinemodeofsecretion

– Ductopensintohairfollicle

– Secretessebum• Hairoil

CeruminousGlandsWaxGlands

• Modifiedapocrinesweatglands

• Secretecerumen– Earwaxisamixtureofless

viscoussecretionsfrommodifiedapocrinesweatglands,sebumanddeadepithelialcells

• Holocrinemodeofsecretion

• Foundonlyintheexternalauditorymeatus

• Drainintoguardhairsintheear