309a0dbd-77d4-46ec-ab2e-00737451b865.pdf - INTEGUMENTARY...

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INTEGUMENTARY SYSTEMFunctions of the Integumentary System1.ProtectionAgainst abrasion and UV lightPrevents entry of microorganismsPrevents dehydration2.SensationSensory receptors that can detect heat, cold, touch, pressure, and painTemperature regulation by controllingBlood flow through the skinSweat gland activity3.Vitamin D productionThe ultraviolet rays stimulates the production of Vitamin D4.Excretion of small amounts of waste productsComponents of the Integumentary SystemskinhairnailsglandsThe SkinWeighs 9 lbs.Used to determine body fatConsists of three major regions1.Epidermis:outermostregion (superficial)Resists abrasionReduces water loss2.Dermis:middle region(bulk of skin)Responsible for most ofthe structural strength ofthe skinLeather is produced fromthe dermis of animals3.Subcutaneoustissue(hypodermis):deepest regionNot really part of the skinConnectstheskintounderlying muscle or boneEpidermisComposed of keratinized stratified squamous epithelium, consisting of four distinct celltypes and four or five layers
Cell types include keratinocytes, melanocytes, Merkel cells, and Langerhans’ cellsOuter portion of the skin is exposed to the external environment and functions inprotectionCells of the Epidermis1.KeratinocytesMost abundant cell typesProduce the fibrous protein keratinGives skin its protective properties2.MelanocytesProduce the brown pigmentmelaninFound in the deepest layers of the epidermis3.Langerhans’ cellsEpidermal macrophagesHelp activate the immune system4.Merkel cellsTouch receptors in association with sensory nerve endingsEpidermal Layers1.Stratum Basale(Basal Layer)Deepest epidermal layer firmly attached to the dermisStructural strength is provided by desmosomes and hemidesmosomesConsists of a single row of the youngest keratinocytesCells undergo mitotic divisions ~every 19 days10-25% are melanocytes2.Stratum SpinosumMelanin granules and Langerhans’ cells are abundant in thislayerMelanin is taken up by the keratinocytes and accumulates on the “sunny side” toprotect the nucleus from UV damage3.Stratum GranulosumDrastic changes in keratinocyte appearance occursKeratohyalin and lamellated bodies (waterproofing) accumulate in the cells of thislayerAbove this layer the epithelial cells die because they are too far from the dermis4.Stratum Lucidum

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Term
Fall
Professor
N/A
Tags
Ultraviolet, Stratum Corneum, Skin anatomy

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