integumentary system. facts about your skin inegument = means covering integumentary system- skin,...

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I n t e g u m e n t a r y S y s t e m

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  • Integumentary System

  • Facts about your SkinInegument = means covering

    Integumentary System- skin, nails, hair, membranes, sweat, & oil glands

    Surface Area = 1.2 to 2.2 square metersWeight = 4 to 5 kgThickness 1.5 - 4.0 mm 7% of average body weight for an adult

  • Functions of SkinProtectionCushions and insulates and is waterproofProtects from chemicals, heat, coldNot helpful against organic solvents, heavy metals or plant oils from poison oakScreens UVAcid Mantel keeps down bacteria ~pH 5Macrophages gobble up invaders Synthesizes vitamin D with UV

  • Functions of the SkinRegulates body heatSweat 500ml a day if about 31-32 Cvessel dilate & constrict Prevents unnecessary water lossBut Lipid soluble Vitamins and steroids inSensory reception (nerve endings)ThermoreceptorsPacinian receptors Bumps and deep pressureMeissners corpuscles & Merkel disksAware of caress of clothing

  • Layers of the SkinEpidermisDermisHypodermis

  • 1) EpidermisEpi = UponKeratinized stratified squamous epithelium

    nutrients reach by diffusion/ avascular

    Outer layer of dead skin cells called cuticle with living level underneath. Ashiness is caused by this layer of dead skin cells being very rough and raggedy

    DUST you see around is made up of dead skin cells!

  • Epithelium: layers (on left) and cell types (on right)

  • RememberFour basic types of tissue

    Epithelium epidermis just discussedConnective tissue - dermisMuscle tissueNervous tissue

  • 2) DERMISThick, tough, leathery, flexible layer Made of connective tissueVascularized contains blood vesselsAnchors the epidermisCritical in Temperature regulation contract and expand

    In the dermis:Oil glandsSweat glandsHair folliclesFat tissueNervesConnective tissueBlood vessels

  • Two layers Papillary areolar connective tissue; includes dermal papillae Reticular rticulum (network) of collagen and reticular fibers

  • Fingerprints, palmprints, footprintsDermal papillae lie atop dermal ridgesElevate the overlying epidermis into epidermal ridgesAre sweat films because of sweat poresGenetically determined

    Flexion creasesDeep dermis from continual folding

  • Finger Print

  • 3) HYPODERMISSubcutaneous Tissue /Hypodermis / superficial fascia not really part of skin, but helps with protective functionssuperficial to connective tissue around bonesloose enough for free movementAdipose tissue different patters of accumulation for men and women (grows when we gain weight)shock absorber & insulatorDeep pressure receptors

  • Cells of the Epidermis Keratinized stratified squamous epithelium

    Four distinct cell types KeratinocytesMelanocytes Merkel CellsLangerhans/ Epidermal Dendrite Cells

  • KeratinocytesMost epidermal / superficial cellsProduce keratin kera= horn . Fibrous protein that gives stretchConstantly in mitosis & pushed upwardsBy the time they are on the surface they are deadNew epidermis every 25-45 daysFriction= keratin formation is accelerated therefore callus- a thickening of the epidermis

  • Melanocytes Spider shaped epithelial cells that make MelaninDeepest layers of the epidermisMelanin made & collects in granules called melanosomesActin filaments move them along till they are taken up by Keratinocytes

    Granules accumulate on the superficial sunny side of the Keratinocytes nuclei & protect nucleus from harmful UV rays

  • Merkel CellsShaped like a spiky hemisphereHelp with sensory of touch

  • Langerhans Cells / Epidermal Dendrite CellsMacrophages (pac mans) that help activate our immune system

  • Layers of the EpidermisThick skin= covers palms, fingertips, and soles of the feetFIVE layers/ strata

    Thin Skin= rest of the bodyFOUR layers (no stratum lucidum)

    Deep to Superficial:

    stratum basalstratum spinosumstrata granulosumstrata lucidum strata corneum

  • Epidermis and dermis of (a) thick skin and (b) thin skin(which one makes the difference?)

  • Stratum basale/ stratum germinativum/ Basal LayerDeepest epidermal layer Single row of cells Attached to dermis w/ a wavy boarder line10-25% of cells are melanocytes & their branches undergoing mitosis

  • stratum spinosum/Prickly Layer several cell layers thickkeratinocyte in this layer are spiny

  • strata granulosum/ Granular Layer 3-5 cell layerkeratinocyets flatten & start to dienot enough oxygen and nutrients b/c pushed away from blood source

  • strata lucidum/ Clear Layer

    o thin translucent bando only in thick skino start making distinct layer

  • strata corneum/ Horny Layer

    20-30 cells thick of epidermal thicknessthickened plasma membrane of cells protects from abrasion & penetrationglycolipid acts as a water proofprotects body from heat and water lossdandruff 18kg= 40 lbs in a lifetime

  • Skin Color1. Melaninsame # of melanocytes

    kind + amount of melanin made & retainedDarker = more darker melanosomes & retain longer

    Freckles & pigment moles are accumulation of melanin

    Sunlight causes melanin buildupto protect from UV

  • Skin Color2. CaroteneYellow-orange pigmentAccumulate in the stratum corneumPalms of hands, soles of feetEat lots of rich carotene foods- becomes more obvious3. HemoglobinPinkish hue of light skin b/c can be seen through light skin

  • Skin AppendagesDerived from epidermis but extend into dermisIncludeHair and hair folliclesSebaceous (oil) glandsSweat (sudoiferous) glandsNails

  • HAIRHair growth: averages 2 mm/weekActive & Resting phase then ShedAt the base of the follicle, hair papillaContains blood vessels and nervesBulbContains matrix epithelial cells responsible for growthContains melanocytes

  • Functions of hairWarmth Sense light touch of the skinProtection scalp

    Hair colorAmount of melanin for black or brown; distinct form of melanin for redWhite: decreased melanin and air bubbles in the medullaGenetically determined though influenced by hormones and environment

  • Hair and hair follicles: complexDerived from epidermis and dermisEverywhere but palms, soles, nipples, parts of genitalia

    *arrector pili is smooth muscle*Hair papilla is connective tissue________________Hair bulb: epithelial cells surrounding papilla

  • Nailshard keratinCorresponds to hooves and clawsGrows from nail matrix

  • Sebaceous (oil) glandsEntire body except palms and solesOils and lubricates

  • Sweat GlandsEntire skin surfaceexcept nipples and part of external genitaliaPrevent overheating500 ml to 12 L /day! Humans most efficient (only mammals have)Produced in response to stress as well as heat