Integumentary SystemThe Skin!

Integumentary SystemAnatomyEpidermal layerDermal layerPhysiologyRegulates body temperatureProtects internal tissuesSensation touch, temperature, pressure, painExcretion water, salts, heatImmunityBlood reservoir many tiny blood vesselsMakes vitamin D

Cross Section of Skin

Skin has 2 layersEpidermis outer, thinner portion composed of epitheliumDermis inner, thicker part composed of connective tissue

EpidermisKeratinized stratified squamous epithelium cellsKeratinocytes produce protein keratinKeratin fibrous protein for protection and waterproofingMelanocytes produce melaninMelanin pigment for skin color and absorbs UV light

Epidermis deep to superficial layersThin skin most of the bodyStratum basale (stratum germinativum)Stratum spinosumStratum granulosumStratum corneum (thin layer)Thick skin palms, soles of feetStratum basale (stratum germinativumStratum spinosumStratum granulosumStratum lucidumStratum corneum (thick layer

Stratum Germinativum (basale)Basal (base) cell layer (germinal) undergoes continuous mitotic divisionProduces all the other layersMade up of stem cellsSimple cuboidal or columnar

Stratum spinosumWhen prepared, shrink to have thorn-like projectionsHave melanocytes and Langerhans cellsHelp with skin immunity to microbes

Stratum granulosumCell apoptosis occurs hereContains lamellar granules provide waterproof sealant to skinTransition between alive layers and dead layers of skin

Stratum lucidumConsists of flattened, dead, clear keratinocytes

Stratum corneumKeratinization accumulation of keratin by moving through epidermal layersDead cells are sloughed off (shed) and replaced by newly dead cells from deeper layersMade up of dead stratified squamous cellsCallus abnormal thickening of stratum corneum

DermisComposed of connective tissueBlood vessels, nerves, glands, hair follicles2 regionsPapillaryReticular

Papillary regionConsists of areolar C.T with elastic fibersDermal papillae projections into the dermis create ridges: fingerprintsContain tactile receptors corpuscles of touchNerves sensitive to touch Pacinian corpuscles sensitive to pressureFree nerve endings sensitive to temperature

Reticular regionMade of connective tissue, mainly collagen and elastic fibersAlso containsAdipose tissueHair folliclesNervesOil glandsSweat glands

Skin colorGenetically determinedMelanin brown-black pigment, number the same in all races; production of melanin differsCarotene yellow-orange pigmentHemoglobin reddish/pinkish tint in Caucasians

Skin PhysiologyVitamin D DeficiencySkin needs UV rays to initiate production of vitamin DVitamin D is turned into calcitrol which helps in absorption of calcium in intestinesLack of vitamin D leads to rickets or osteomalacia

Skin PhysiologyRegulates body temperatureDone with sweat glands (sudoriferous)Water/salt comes to surfaceAs water evaporates, heat is taken away with the waterEccrine function when hotApocrine function during stressful times

Skin PhysiologyOil Glands (sebaceous)Released onto shaft of hairGoes to surface of skin to:Protect, lubricate, and waterproof skinProblemDrainage becomes blocked pimplesProduction of sebum (oil) is controlled by sex hormones

Skin PhysiologyCeruminous (wax) glandsSecrete wax into ear canalFunctions:Insect repellantKeeps eardrum flexibleProblemExcess ear wax can interfere with hearing

Hair

Hair and HormonesHisutismHigher than normal levels of androgen (hormone) cause excessive hair on lip, chin, chest, thighs, abdomenMale-pattern baldnessAndrogen inhibits hair growth for genetically predisposed males

Skin Wound HealingEpidermal Wound Healing near the surface (abrasion scrape), 1st/2nd degree burnsDetached, basal cells migrate till they meet each otherCell division fills in the spaceNo bleedingEpidermal growth factor (EGF) protein hormone that stimulates growth of dermal cells and fibroblasts

Epidermal Wound Healing

Skin Wound HealingDermal (deep) Wound Healing4 phasesInflammatory phaseMigratory phaseProliferative phaseMaturation phaseScar formation

DWH - PhasesInflammatoryclot forms (platelets)WBC arrive for defenseMigratoryclot becomes a scab by fibroblast productionEpithelial cells begin to regrow

DWH - PhasesProliferativeEpithelial cells grow beneath scabCollagen fibers depositedTissue is reformedMaturationSloughing off of scabCollagen fibers organize

DWH What would I see between these 2 phases?

Skin DisordersCancerWartsBurns

Skin CancersOver 1 million diagnosed each yearArizonans have 3-7x more risk than people in other states3 common typesMelanomaBasal cell carcinomaSquamous cell carcinoma

MelanomaMost dangerous form of skin cancerAppears as:Change in existing moleSmall, dark multicolored spot with irregular borders, elevated or flat, bleed or form scabCluster of shiny, firm, dark bumpsLarger than a pencil eraser

MelanomaBenign not cancerousMalignant - cancerous

Basal Cell CarcinomaCome from cells in stratum basale of epidermisAppear on sun-exposed skin as:Pearly or flesh-colored oval bump with a rolled border, may develop into bleeding ulcerSmooth red spot indented in centerReddish, brown, or bluish black patch of skin on the chest or back

Basal Cell Carcinoma

Squamous Cell CarcinomaArise from squamous cells of epidermisArise from damaged tissueAppear on sun-exposed skin as:A firm, reddish, wart-like bump that grows graduallyFlat spot that becomes a bleeding sore and wont heal

Squamous Cell Carcinoma

SymptomsAny change in size, color, shape or texture of a mole or other skin growthOpen or inflamed skin wound that wont healABCDS of melanomaA asymmetryB borderC colorD diameter

Burns1st, 2nd, 3rd degreeNamed according to severity1st degreeLeast severeRedness or discolorationSwelling and painUsually overexposure to sunOnly epidermis is damaged

Burns2nd degreeAffect epidermis and dermisMay blisterScarring may resultMost painful because nerves are intact but tissue is damagedMay involve loss of skin function

Burns3rd degreeWorst burnMay look white or charredExtend through all skin layers epidermis, dermis, subcutaneous layerSevere to no pain depending on nerve damageRequires skin grafts

Burns