_ch_05_lecture_presentation (1) - CHAPTER 5 INTEGUMENTARY...

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INTEGUMENTARY SYSTEMCHAPTER 5
Integumentary SystemIt consist of Cutaneous Membraneand Accessory Structures
Skin (Integument)Consists of two distinct regionsEpidermisDermisHypodermis
Figure 5.1Skin structure.Hair shaftEpidermisPapillarylayerDermisReticularlayerHypodermisDermal papillaeSweat poreCutaneousplexusAdipose tissueNervous structuresSensory nerve fiberwith free nerve endingsLamellar corpuscleHair follicle receptor(root hair plexus)Appendages ofskinSweat glandArrector pili muscleSebaceous (oil)glandHair follicle
EpidermisKeratinized stratified squamous epitheliumFour or five distinct layersStratum basaleStratum spinosumStratum granulosumStratum lucidum(only in thick skin)Stratum corneumFour cell typesKeratinocytesMelanocytesDendritic (langerhans) cellsTactile (merkel) cells
Figure 5.2aThe main structural features of the skin epidermis.DermisStratum spinosumSeveral layers of keratinocytes unified by desmosomes.Cells contain thick bundles of intermediate filaments made ofpre-keratin.Stratum basaleDeepest epidermal layer; one row of actively mitotic stemcells; some newly formed cells become part of the moresuperficial layers. See occasional melanocytes and dendriticcells.Stratum granulosumTypically five layers of flattened cells, organelles deteriorating;cytoplasm full of lamellar granules (release lipids) andkeratohyaline granules.Stratum corneumMost superficial layer; 20–30 layers of dead cells, essentiallyflat membranous sacs filled with keratin. Glycolipids inextracellular space.
Keratinization is theformation of a layerof dead protectivecells with protectiveprotein KeratinKeratinocytesTightlyconnected bydesmosomes
Melanocytes10–25% of cells indeepest epidermisProduce pigmentmelanin– packagedinto melanosomes.
Tactile (merkel) cellsSensory touch receptorsAssociated with sensory neuron.
Dendritic(langerhans) cellsMacrophages – keyactivators of immunesystem
Thin skin covers most of thebody areas while thick skinis present in the plams ofthe hands and the soles ofthe feet
Cell Differentiation in EpidermisCells change from stratum basale tostratum corneumAccomplished by specialized form ofapoptosisControlled cellular suicideNucleus and organelles break downPlasma membrane thickensAllows cells to slough off as dandruff anddanderShed ~ 50,000 cells every minute
Stratum spinosumStratum basaleMelanocyteDendriticcellKeratinocytesStratum corneumDermisMelaningranuleSensorynerveendingTactile(Merkel) cellDesmosomesStratum granulosum.Figure 5.2bThe main structural features of the skin epidermis.
DermisStrong, flexible connective tissueCellsFibroblasts, macrophages, and occasionally mast cellsand white blood cellsFibers in matrix bind body togetherContains nerve fibers; blood and lymphatic vesselsContains epidermal hair follicles; oil and sweatglandsTwo layersPapillaryReticular

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Term
Spring
Professor
A. Ebrahim
Tags
Physiology, Anatomy, Stratum Corneum, Stratum Granulosum, root hair plexus, hair follicles, Hair follicle receptor

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