PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Graded PotentialsSlide 26Slide 2716-1DermisPapillary layerThin areolar CTSuperficial blood vessels and nervesDermal papillae folded into epidermis16-2Reticular layerDense irregular CTThick collagen fibersElastinStrong but stretchyPacinian corpuscle detects pressure16-3Sudoriferous glandsEccrine sweat glands: Coiled, tubular epithelial glandAll skin, hands, feet, foreheadSecrete dilute, acidic fluidAcid mantle protects skinEvaporative heat lossActivated by nervesincreased temperatureremove heat from blood16-4Apocrine: larger sweat glands in genital, axillary areasFluid, lipids, proteinsPain, stress, Ceruminous: ear canal, wax protection16-5Sebaceous glandsHolocrine secretion: lysed cell contentsSebum: dead cells, lipidsSecreted into hair follicle, ductsLubricationAntibiotic16-6Hair structureHair shaftProjects filament of dead, keratinized cellsHard keratin: tough, won't flakeHair rootForming filament in skinHair follicleSupporting cells forming shaft16-7layers of cells in shaftMedulla Large cells, airCortexFlattened cellsCuticleSingle cell layer which compacts and contains inner cells16-8Integumentary System (skin)FunctionsProtectionMechanical: physical barrier to bacteria, Chemical: secretions destroy bacteriaBiological: skin cells destroy invaders16-9HomeostasisWater: reduced exchange with environmentThermal: important heat loss surfaceSecretionSweat: heat lossOil: antibiotic, lubricationHormones: Vitamin DSensoryMechanical: touch, painThermal: heat16-10EpidermisAvascular Keratinized stratified squamous epitheliumSpecialized cell typesKeratinocytesSoft keratin (protein)DesmosomesMigrate upward and shrivel until dead keratin is left16-11MelanocytesMelanin (pigment)Insert melanin granules in superficial surface of keratinocytes16-12Dendritic (Langerhans) cellsBlood cellsMacrophage-likeMerkel cellTouch receptor16-13Cell layers(Epidermis)Stratum basaleBasal layerActive mitosis of keratinocytesMelanocytes and Merkel cells16-14EpidermisCell layersStratum spinosumDesmosomes and intermediate filaments for strength, barrierUpward moving keratinocytes are flatteningLangerhans cells16-15EpidermisCell layersStratum granulosumKeratinocytes flatten, become granular and disintegrateGranuleskeratin fibersglycolipid waterproofingFar from blood16-16EpidermisCell layersStratum lucidumThick skin only (palms, soles)Clear, flat, dead keratinocytesAdditional strength16-17Stratum corneumDead cell keratin, membranes, glycolipid, DNAMechanical protectionBarrier to water and solute movementFlakes ofEpidermisCell layers16-18Classes of neurons: Structural16-19Glial (neuroglia, indispendible supporting) Cellsmost of weight and cell number of CNSbrain cancers are usually gliomasastrocytes-star-shaped cells in CNSconnect neurons to capillariesnourish, control ECF compositionscafolding16-20ependymal cellsciliated epithelium between neurons and fluid-filled cavities in CNS (ventricles)cushioning, control ECF composition16-21oligodendrocyteswrap membranes around multiple axons in CNSinsulate axons with compressed membranesSchwann cells-wrap cell membranes around axons, growth16-22Myelinated nervesbundled groups of myelinated axons in nerveswhite matter in CNSperipheral nervesUnmyelinated axons, dendrites, cell bodies are gray matter in CNS16-23Voltage across membrane can be measuredfirst done in LoligoVoltmeterPlasmamembraneMicroelectrodeinside cellGround electrodeoutside cellAxonNeuronOhms LawV=IR16-2416-25Graded Potentials16-26 Action potentials (nerve impulses)If depolarization great enough, graded potentials elicit action potentialsmembrane depolarizes, reverses polarity to positive16-27 Action potentials (nerve impulses)Threshold potential: membrane potential at which special class of voltage gated Na+ channels openNa+ entry depolarizes