Review bio Exam #2 - 1 Chapter 5 The Integumentary System...

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1 Chapter 5 The Integumentary System integument skin, hair, nails, sweat glands, sebaceous glands functions of integumentary system protection against abrasion, chemical  elements, and water loss; temp.  regulation, sense organ (receptors detect  pain, hot, cold, itch, tickle, pressure, etc.); synthesize and store Vitamin D; keeps  out UV light and prevents genetic  mutations; diagnostic organ (excessive  itching can be diabetes); organ of sexual  attraction (pheromones) two tissue layers of skin epidermis and dermis epidermis epithelial surface layer of the skin; 5  layers; renewed every 20-30 days;  stratified keratinized squamous dermis deeper connective tissue layer of the skin; binds epidermis to hypodermis hypodermis (subcutaneous layer) not considered part of the skin; loose CT  mainly in the form of adipose that  attaches the dermis to deeper tissues 4 cell types in epidermis keratinocytes, melanocytes, Langerhans  cells, Merkel cells keratinocytes produce keratin melanocytes produce melanin Langerhans cells part of immune system; derived from  bone marrow, function in presenting  foreign substances to lymphocytes Merkel cells ends of sensory neurons
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2 how many layers of the epidermis? 4 or 5, depending on the degree of friction and mechanical pressure applied to the  skin; thick skin found in smooth non hairy  parts (soles of feet/palms) & thin skin  found everywhere else layers of epidermis (deep --> superficial) stratum basale or germanitivum; stratum  spinosum; stratum granulosum; stratum  lucidum; stratum corneum stratum basale/germanitivum includes cells: keratinocytes,  melanocytes, Merkel cells *keratinocytes rest upon the basal lamina  of the basement membrane *melanocytes use an enzyme (tyrosinase) to produce melanin: melanin granules  accumulate in these cells and exit by  pinching off- they’re distributed through  epidermis and surround the nucleus  protecting DNA from genetic mutation *Merkel cells are most numerous in the  stratum basale of the fingertips (rapid  mitosis) stratum spinosum cells : keratinocytes, Langerhans *8-10 layers of closely packed  keratinocytes (cuboidal &held together by  desmosomes) *cells accumulate keratohyalin *Langerhans cells are immunologically  active *in areas exposed to friction and  abrasion, they don’t separate, they  produce and accumulate keratohyalin  (protein) *provides flexibility and strength
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3 stratum granulosum *lamellar granules: secrete a water  repellent lipid sealant in cytoplasm * 3-5 layers of dying keratinocytes  ( shrunken nucleus) * keratohyalin granules are present in  cytoplasm (condense and referred to as  lamellar granules that act as a sealant) stratum lucidum *only found in thick skin
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