the integumentary system the skin, hair, & nails… the “underappreciated” system

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The The Integumentary Integumentary System System The skin, hair, & nails… The skin, hair, & nails… The “underappreciated” The “underappreciated” system system

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  • The Integumentary SystemThe skin, hair, & nailsThe underappreciated system

  • Objectives:List the components of the integumentary system & describe their physical relationship to each other & to the subcutaneous layer.Specify the general functions of the integumentary systemDescribe the main structural features of the epidermis, and explain their functional significanceExplain what accounts for individual and racial differences in skin, such as skin colorDiscuss the effects of ultraviolet radiation on the skin and the role played by melanocytes.Describe the structure and functions of the dermisDescribe the structure and functions of the subcutaneous layerDiscuss the various kinds of glands in the skin and the secretions of those glandsExplain how the sweat glands of the integumentary system play a major role in regulating body temperature.Explain how the skin responds to injury and repairs itselfLearn selected clinical terminology

  • Integumentary OverviewThe integument includes the cutaneous layer or skin which includes the epidermis & dermis. The accessory structures include hair, nails, and multicellular exocrine glands.Deep to the dermis, the loose connective tissue of the subcutaneous layer, or hypodermis.

  • Functions of the IntegumentProtectionExcretionTemperature maintenanceNutrient StorageVitamin D3 synthesisSensory Detection

  • The EpidermisThin skin formed by 4 layers of keratinocytes covers most of the bodyThick skin covers palms of hands & soles of feet.Provides mechanical protection, prevents fluid loss, keeps out bugs

  • The Epidermis

  • Layers of the EpidermisStratum corneumStratum lucidum (in thick skin)Stratum granulosumStratum spinulosumStratum basale or germanitivum

  • Layers of the Epidermis

  • Stratum germinativumInnermost layerForms epidermal ridges - extend into the dermis, increasing area of contact Dermal papilla extend between ridgesRidges = fingerprints; increase surface area of skin and increase friction. Unique to individuals!!

  • Germinative cells dominate layerThese cells undergo mitosis (stem cells)Merkel cells (touch receptors) found on skin surfaces which lack hair.Melanocytes present in layer. These cells contribute to skin color.

  • Stratum Spinosumspiny layerConsists of 8-10 layers of cellsSpiny appearance due to tissue prepLangerhans cells present - these cells participate in the immune response.They stimulate defense against 1) microorganisms & 2) superficial skin cancers

  • Stratum GranulosumGrainy Layer3-5 layers of karatinocytesCells have stopped dividing by nowMake lots of keratin. - protein, waterproof

  • Stratum LucidumFound only in thick skinPalms of hands & Soles of feetClear layerCells are flattened, densely packed, and filled with keratin.

  • Stratum CorneumTop layer15-30 layers of keratinized cellsCells shed from this layer in large groups15-30 days for a cell to move from s.germinativum to s. corneum.Cells remain in S. corneum approx. 2 weeks before shed or washed away.Water resistant layer, not waterproof

  • Skin colorInteraction between epidermal pigmentation and dermal circulationCarotene & melanin important pigmentsCarotene = orange-yellow pigmentCarotene converted to Vitamin AMelanin = brown, yellow-brown, or black pigmentation made by melanocytes

  • MelanocytesLocated in the stratum germinitivumRegardless of ethnic variation, the ratio of melanocytes to germinative cells ranges between 1:4 and 1:20, depending on region of the body.Variation in skin color due to synthetic activity of the melanocytes, not numberMelanin protects against UV damage.

  • Images of Melanocytes..