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Anatomy and Physiology 121: The Integumentary SystemFunctions of the IntegumentarySystem1. Protection2. Body Temperature Regulation3. Metabolic Functions4. Blood Reservoir5. Excretion6. Cutaneous SensationIntegumentary system = skin, hair, nails, sweat and oil glandsIntegument = covering (like the skin)Composed of two regions:1.Epidermis = outermost layer composed of epithelial tissue (cells)2.Dermis = underlying tough , leathery layer composed of fibrousconnective tissueEpidermis = thick keratinized stratified squamous epitheliumConsists of:4 distinct cell types4-5 distinct layersCells of the Epidermis:1.Keratinocytes = bulk of epithelial cells, produce keratin2.Melanocytes = produce the pigment melanin, found in basal layer ofepidermis3.Langerhan’s cells = macrophagesthat help activate the immune response4.Merkel cells = found at epidermal-dermal junction, associated withsensory nerve endingsMerkel disc= functions as sensory receptor for light touchLayers of the Epidermis: from deepest to most superficialThin Skin: consists of 4 layersStratum BasaleStratum SpinosumStratum GranulosumStratum Corneum
Thick Skin: consists of 5 layersStratum BasaleStratum SpinosumStratum GranulosumStratum LucidumStratum CorneumStratum Basale (Basal Layer)•Deepest epidermal layer•Consists of a single row of cells•Only layer to undergo continuous mitosis•10-20% of cells are melanocytes•Some Merkel CellsStratum Spinosum (Prickly Layer)•Thickest layer, several cell layers thick•