Chapter_10.ppt - UNIT 2 Chapter 10: Skin and Its Appendages...

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UNIT 2Chapter 10: Skin and ItsAppendages
INTRODUCTIONSkin (integument) is the body’s largestorganApproximately 1.6 to 1.9 m2in average-sized adultIntegumentary system describes the skinand its appendages: hair, nails, and skinglands
STRUCTURE OF THE SKINSkin classified as a cutaneous membraneTwo primary layers: epidermis and dermis; joined bydermoepidermal junction (Figures 6-1 and 6-2)Hypodermis lies beneath dermisThin and thick skin (Figure 6-3)Thin skin covers most of the body’s surface (1 to 3 mmthick)Thick skin covers soles and palms (4 to 5 mm thick)
STRUCTURE OF THE SKIN: EPIDERMISEpidermisCell types (Figure 6-4)Keratinocytes: constitute more than 90% of cellspresent; principal structural element of the outerskin; sometimes calledcorneocytesafter they arefully keratinizedMelanocytes: pigment-producing cells (5% of thetotal); contribute to skin color and filter ultraviolet(UV) lightEpidermal dendritic cells: branched antigen-presenting cells; play a role in immune response;also calledLangerhans cellsTactile epithelial cells (Merkel cells): attach tosensory nerve endings to form “light touch”receptors
STRUCTURE OF THE SKIN:EPIDERMIS (cont.)Cell layersStratum basale (base layer): single layer ofcolumnar cells; only these cells undergomitosis and then migrate through the otherlayers .Stratum spinosum (spiny layer): cells arrangedin eight to 10 layers with desmosomes thatpull cells into spiny shapes; cells rich in RNAStratum germinativum (growth layer): anothername for stratum basale or stratum spinosumand stratum basale together
STRUCTURE OF THE SKIN:EPIDERMIS (cont.)Stratum granulosum (granular layer): cellsarranged in two to four layers and filled withkeratohyalin granules; contains high levels oflysosomal enzymesStratum lucidum (clear layer): cells filled withkeratin precursor calledeleidin;absent in thinskinStratum corneum (horny layer): mostsuperficial layer; dead cells filled with keratin(barrier area)

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Term
Spring
Professor
Araceli Rodriguez
Tags
Stratum lucidum, Skin anatomy, APOCRINE SWEAT GLANDS, stratum germinativum

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