Unit VII: Integumentary System (Skin, Nail & Hair)

At the completion of this unit, learners will be able to: 1. Describe the structure of two layers of skin  Epidermis  Dermis 2. Briefly discuss the structure & function of skin derivatives.  Sweat gland  Sebaceous gland  Hair  Nail
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3. Discuss the following functions of skin  Protection  Regulation of body temperature  Sensation  Absorption  Excretion

1. 1
The Skin: Anatomy &
Physiology
By
Syed Yousaf Shah

2. 2
Introduction
Largestorganinthebody
Variesinthicknessatdifferentparts(<0.5mmateyelidsto>5
mmonmiddleofupperback)

3. Anatomy Of The SkinBeneath epidermis
Thicker layer
Connective tissue
Dermis
Outermost layer
Epithelial tissue
Epidermis
Skin
3

4. 4
Epidermis
Stratifiedsquamousepithelium
Nobloodvessels
Inpalmsofhandandsolesoffeet,epidermisisthicker
Composedoffivelayers:
[1]Stratumcorneum
[2]Stratumlucidum
[3]Stratumgranulosum
[4]Stratumspinosum
[5]Stratumbasale

5. 5
[1]StratumBasale
Singlelayerofcolumnarorcuboidalcells
Lowersurfaceofcellsattachedtodermis
Receivesnutrientsfrombloodinthedermalvessels
Mitosisoccursinthislayer
Oldercellsexpelledtoouterlayer
Melaninisproducedinthislayer

6. 6
Stratum Basale

7. 7
[2]StratumSpinosum
Pricklecelllayer
Severallayersofpolyhedral(many-sided)cells
Interlockingspine-likeprojectionshelpbindingofthislayer
Activeproteinsynthesistakesplace(indicatescellgrowthand
division)
Obtainnutrientsthroughfineelements
Keratinizationbeginsinthislayer
Nuclei-containingcellschangeintoflatcellscomposedofhard
durableprotein)

8. 8
Stratum Spinosum
Contain Desmosome

9. 9
[3]StratumGranulosum
Granular+2to4cellsthick
Cellscontainkeratohyalineingranules
Finalstagesofkeratinizationoccur
Lossoffluid,nucleusdisintegrates
[4]StratumLucidum
Transparentlayer
Flat+translucentdeadcells
ProtectionagainstUV
Lucidumappearsinpalmofhandsandsolesoffeettoprotect
againstsunburn

10. 10
[5]StratumCorneum(HornyLayer)
Thicklayerofdeadcells
Softkeratin(keepskinelastic)
Cellsbelowcontainfattysubstratekeepskinwaterproof+
preventskincrackingandallowingbacteriainside

11. 11
Epidermis

12. 12
Dermis
Trueskin
Highlyelastic,toughandflexibletissue
Meshworkofcollagenous,reticularandelasticfibres
CollagenousFibres
Providesupportforskin
ReticularFibres
Thinner,yetstillprovidesupport
ElasticFibres
Skinflexibility

13. 13
CellsOfTheDermis
a) Fibroblasts
b) Fatcells
c) Macrophages
Dermissubdividedintotwomainlayers:
{1}Upperpapillarylayer
{2}Reticularlayer

14. 14
[1]UpperPapillaryLayer
Looseconnectivetissue
Containprotrusionsintoepidermiscalled“PAPILLAE”
Finecapillariestocarrywasteaway+providenourishmentand
oxygen
Nerveendingsforheat,pain,cold,pressureandtouch
(Meissner’scorpuscles)
Doublerowofpapillaebettergrippingbyhandsandfeet+
distinctivefingerprintpatterns

15. 15
[2]ReticularLayer
Elasticnetworkoftoughcollagenfibresinterwovenwithelastic
fibres
Collagenousfibresarrangedinspecialpattern
Incisionsmadeparalleltotheselinesduringsurgerywound
healsfaster
Containssebaceousandsweatglands,arrectorpilimuscleand
hairfollicle
Paciniancorpusclesaredistributedthroughthedermisand
functionaspressurereceptors
Stretchmarksandpregnancyduetobreaksincollagenand
elasticfibres

16. 16
Dermo-epidermal Junction

17. 17
Dermo-epidermal Junction

18. 18
Hypodermis
“Subcutaneous”layer
Thickerthandermis
Thickerinfemales
Ductsofsweatglandsandbasesofhairfollicles
Areaforformationandstorageoffatdueto:
@ Adiposetissue–containingfatcells
@ Areolartissue–tissueelasticity

19. 19
Hypodermis

20. 20
DevelopmentalAnatomyoftheSkin
Dermisandepidermisarederivedfromdifferentembryological
tissues
Epidermisderivedfrom“ECTODERM”
Dermisderivedfrom“MESENCHYME”

21. 21
GlandsOfTheSkin
Twotypes:EccrineandApocrine
EccrineGlands
Distributedalmostallroundthebody
Secretoryportioninhypodermis
ApocrineGlands
Armpitsanddarkregionsofnipple
Secretesfattysubstances
ThesereacttoairYOUSTINK
SweatGlands

22. 22
SebaceousGlands
Locatedinthedermis
Lubricationandprotection
Clusterofcells
Breakdownofinnercellsintheclustersebumformation
Connectedtohairfollicles
Sebumfightbacteriaandfungi
Blackheadsduetoblockedglands

23. 23
Hair
Shaft=protrudesfromskin
Root=embeddedinskin
Folliclesurroundshair
Arrectorpilimuscle=bundleofsmoothmuscle
Arrectorpilicauses:
a) Hairerection
b) Sebumreleasefromthesebaceousglands

24. 24
Anatomy Of The Skin

25. 25
Anatomy Of The Skin

26. 26
Burns
Seriousnessofburnsclassifiedaccordingto:
[1]Extent(sizeofbodyareainvolved)
[2]Depth(Howmanylayersoftissueareinjured)
FirstDegreeBurn
e.g.Sunburn
Epidermisdamagedbutnotdestroyed
Treatedbycoldwater
<10%ofbodysurfaceinvolved

27. 27
SecondDegreeBurn
Epidermisdestroyed
Dermispartlydestroyed
>15%ofbodysurfaceinvolved(10%forchild)
Bodycapableofregeneratingnewskin
ThirdDegreeBurn
Epidermis,dermisandunderlyingissueareinvolved
Burnstoface,eyelids,hands,feetand>20%ofbodysurfaces
Lesspainfulthanseconddegreeburnsbecausenerveendings
aredestroyed
Treatedbyskingraft

28. 28
Bedsores
Skinclosetoboneandunderconstantpressure
Bloodvesselscompresseddepriveaffectedtissuesofoxygen
andnutrients
e.g.shoulderblades,hipsandelbows
Firstsignisreddenedwarmspots
Spotsturnpurplish(indicateblockedbloodflow)
Skinbreaksandinfectionoccurs

29. 29
FunctionsOfTheSkin
Non-specificimmunity(detailstofollowinlaterlectures)
[1]Protection
Anatomicalbarrieragainstinfection
Melanin=screenoutexcessUVrays
Whenmelaninisdarkenedbythetantransferredtoouterskin
layers(suntan)skinlesssensitivetosunrays
Darkskinduetowiderdistributionofmelaninbeyondstratum
basaleintohigherlevelsofepidermis

30. [2]ThermoregulationControl of heat production
Shivering
Skeletal muscle
Motor neurons
Control of heat loss
Skin vasocontriction and vasodilation
Skin blood vessels
Sympathetic nervous system
Control of heat loss
Sweating
Sweat glands
Sympathetic nervous system
Hypothalamic thermoregulatory integrating centre
Peripheral Thermoreceptors (Skin)
Skin temperature
30

31. 31
[3]SensoryPerception
Millionsofnerveendings
Receptorforpain,heatandpressure
Therefore,maintainhomeostasis
[4]Excretion
Excretionoflacticacidandsodiumchloride
Urea(1gnitrogenouswasteeliminatedthroughskinperhour)

32. [5]Vitamin D Synthesis
32Promotes absorption of calcium and phosphate through intestine
Active vitamin D
Modification by liver and kidney enzymes
Vitamin D3 (Cholecalciferol)
Vitamin D precursor (in skin)

33. 33
Commonly UsedTermsDescribingSkin
Conditions
Intact“Skinisunbroken”
Contusion“Injuryinwhichskinisunbroken”
Excoriation“Removalofanareaoftheskin”
Abrasion “Spotrubbedbareofmucousmembraneorskin,
andtherebydamaged”
Cyanosis “Dusky,bluishcolourusuallyseeninthelipsandon
thenailbeds,causedbylackofoxygen”