integumentary system & glands - mt. sac faculty...
TRANSCRIPT
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
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
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