The integumentary system

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The integumentary system

  1. 1. T- 1-855-694-8886Email- info@iTutor.comBy iTutor.com
  2. 2. The integument as anorgan, and is an alternative name forskin.The integumentary systemincludes the skin and the skinderivatives hair, nails, andglands.The integument as an organ:
  3. 3. The IntegumentIs the largest system of the body 16% of body weight, 1.5 to 2m2in area, The integument is made up of two parts:1. Cutaneous membranea. Epidermis– Superficial epitheliumb. Dermis – underlying CT with blood supply2. Accessory structuresa. Hairb. Nailsc. Exocrine Glands
  4. 4. Protection First line of defense against Bacteria Viruses Protects underlying structures from Ultraviolet (UV) radiation DehydrationVitamin D production Needed for calcium absorptionSensation Sensory receptors
  5. 5.  Body temperature regulationIf too hot Dermal blood vessels dilate Vessels carry more blood to surface so heat can escapeIf too cold Dermal blood vessels constrict Prevents heat from escaping ExcretionSmall amounts of waste products are lost throughperspiration
  6. 6.  Understanding how the skin can function in these manyways starts with understanding the structure of the 3layers of skinThe EpidermisEpithelial tissueDermisDense connective tissue proper – irregularHypodermisSubcutaneous tissue- loose connective tissue properand adipose tissue
  7. 7. EpidermisDermisHypodermisorsubcutaneous layer
  8. 8. The EpidermisIs a vascular stratified squamous epitheliumNutrients and oxygen diffuse from capillaries in the dermisCells of the EpidermisKeratinocytesContain large amounts of keratinAre the most abundant cells in the epidermis
  9. 9. The structural relationship andinterface between the epidermisand underlying dermis. Theproportions of the various layersdiffer with the location sampled.DermisEpidermisEpidermalridgeDermalpapilla
  10. 10. Thin SkinCovers most of the bodyHas four layers of keratinocytesThick SkinCovers the palms of the hands and soles of the feetHas five layers of keratinocytes
  11. 11. Structures of the Epidermis The five strata of keratinocytes in thick skin From basal lamina to free surface1. Stratum basale2. Stratum spinosum3. Stratum granulosum4. Stratum lucidum5. Stratum corneum
  12. 12. Thick skin LM  210SurfaceStratumcorneumStratumlucidumStratumgranulosumStratumspinosumStratum basaleBasementmembraneDermisPapillary layer of dermisEPIDERMIS
  13. 13. Stratum BasaleIs attached to basement membrane byhemidesmosomesForms a strong bond between epidermis and dermisForms epidermal ridges (e.g., fingerprints)Dermal papillae (tiny mounds)Increase the area of basement membraneStrengthen attachment between epidermis and dermisHas many basal cells or germinative cells
  14. 14. Thick skin SEM  25EpidermalridgePores of sweatgland ductsEpidermal ridges
  15. 15. Stratum Spinosum — the ―spiny layer‖Produced by division of stratum basaleEight to ten layers of keratinocytes bound bydesmosomesCells shrink until cytoskeletons stick out (spiny)Continue to divide, increasing thickness of epitheliumContain dendritic (Langerhans) cells, active inimmune response
  16. 16. Stratum Granulosum — the ―grainy layer‖Stops dividing, starts producingKeratinA tough, fibrous proteinMakes up hair and nailsKeratohyalinDense granulesCross-link keratin fibers
  17. 17. Stratum Lucidum — the ―clear layer‖Found only in thick skinCovers stratum granulosumStratum Corneum — the ―horn layer‖Exposed surface of skin15 to 30 layers of keratinized cellsWater resistantShed and replaced every 2 weeks
  18. 18. The Dermis Located between epidermisand subcutaneous layer Anchors epidermal accessorystructures (hairfollicles, sweat glands) Two components1. Outer papillary layer2. Deep reticular layer Dermis
  19. 19.  The Papillary LayerConsists of areolar tissueContains smaller capillaries, lymphatics, and sensoryneuronsHas dermal papillae projecting between epidermal ridges The Reticular LayerConsists of dense irregular connective tissueContains larger blood vessels, lymphatic vessels, and nervefibersContains collagen and elastic fibersContains connective tissue proper
  20. 20. An inflammation of the papillary layerCaused by infection, radiation, mechanical irritation, or chemicals(e.g., poison ivy)Characterized byitch or painCharacteristicsStrong, due to collagen fibersElastic, due to elastic fibersFlexible
  21. 21. HairPapillarylayerReticularlayerCutaneousplexusPapillaryplexusEpidermalridgesDermalpapillaeCapillary loopof papillaryplexus
  22. 22. The Hypodermis (Subcutaneous Layer)Lies below the integumentStabilizes the skinAllows separate movementMade of elastic areolar and adipose tissuesConnected to the reticular layer of integument byconnective tissue fibersDeposits of Subcutaneous FatDistribution patterns determined by hormonesReduced by cosmetic liposuction (lipoplasty)
  23. 23. The Hair Follicle Hair follicles are the organs that form the hairs.Hair follicles are the organs that form the hairs.Located deep in dermis.Produces nonliving hairs.Wrapped in a dense connective tissue sheath.Base is surrounded by sensory nerves (root hair plexus).Control bacteria
  24. 24. Exposedshaftof hairSebaceousglandArrectorpilimuscleConnectivetissue sheathRoot hairplexusAccessory Structures of HairArrector piliInvoluntary smooth muscleCauses hairs to stand upProduces ―goose bumps‖Sebaceous glandsLubricate the hair
  25. 25. Regions of the HairHair rootLower part of the hairAttached to the integumentHair shaftUpper part of the hairNot attached to theintegumentBoundarybetweenhair shaftandhair rootHair shaftSebaceousglandArrectorpili muscleHair rootConnectivetissue sheathHair bulbHair matrixHair papilla
  26. 26.  Hair Shaft Structure Medulla Core, dead cells contain soft keratin and air to provideflexible Cortex Middle layer, dead cells contain hard keratin to providestiffness Cuticle Outermost, overlapping dead keratinized cells formshiny surface
  27. 27. Head:UV protectionCushion from traumaInsulationNostrils, Ear canals, Eyelashes:Prevent entry of foreign materialBody Hair:sensory detectionRoot hair plexus:Sensory nerves at base of hair follicle that detect slightmovement of hairArrector pili muscle:Attached to every hair follicleContract to stand hair perpendicular to skin surface
  28. 28. NailsProtect fingers and toesMade of dead cells packed withkeratinMetabolic disorders can changenail structureNail ProductionOccurs in a deep epidermal foldnear the bone called the nail rootFree edgeof NailBody ofNailLaternalNail foldLunulaEponychium(cuticle)
  29. 29. Structure of a NailNail bodyThe visible portion of the nailCovers the nail bedLunulaThe pale crescent at the base of the nailSides of nailsLie in lateral nail groovesSurrounded by lateral nail folds
  30. 30. A cross-sectionalviewLateral nail foldNailbodyLateralnailgrooveNailbedPhalanx(bone offingertip)
  31. 31. A longitudinal sectionEponychiumProximal nail foldNail rootLunula Nail bodyEpidermis Dermis Phalanx Hyponychium
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