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Cutaneous Membrane Accessory Structures

Ch 4: Integumentary System. Cutaneous Membrane Accessory Structures. Made up of all 4 tissue types . . . .??. Two Major Subdivisions. Cutaneous Membrane Epidermis Dermis Hypodermis Accessory Structures Excretory glands (?) ? ?. Epidermis. Type of Epithelium? _vascular

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Cutaneous Membrane Accessory Structures

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  1. Ch 4: Integumentary System Cutaneous Membrane Accessory Structures

  2. Made up of all 4 tissue types . . . .??

  3. Two Major Subdivisions • Cutaneous Membrane • Epidermis • Dermis • Hypodermis • Accessory Structures • Excretory glands (?) • ? • ?

  4. Epidermis • Type of Epithelium? • _vascular • Different layers (=strata) • 4 layers in thin skin • 5 layers in thick skin

  5. Stratum Germinativum Cell types: • Stem cells (basal cells) • Melanocytes • Merkel cells (touch receptors in hairless skin only) = stratum basale Stratum germinativum Innermost, single layer

  6. Stratum Spinosum • Stem cell daughter cells (some can still divide) • Melanocytes & Langerhans cells • Establishment of Desmosomes Stratum spinosum Several cells thick

  7. Stratum Granulosum • Cells displaced from stratum spinosum  Keratinocytes • Production of keratohyalin and keratin fibers • Cells start to die. Dehydration leaves interlocked layers of keratin, keratohyalin & PL membranes Stratum granulosum

  8. Stratum Lucidum • In palms of hands and soles of feet • Cells do not stain well  clear (lucid) looking Stratum lucidum

  9. Stratum Corneum • Many layers of flattened, dead cells, filled with keratin • Continually shed in sheaths • Water-resistant but not water proof ( insensible perspiration) • Relatively dry - advantage? • Keratinization occurs everywhere except for anterior surface of eye Stratum corneum 15-30 layers (much thicker in thick skin)

  10. Up to 6 x thicker Where?? Average 0.08 mm Rest of body Thin vs. Thick Skin Refers to epidermis

  11. Contour of skin surface follows pattern of epidermal ridges. Advantage ?? c c Unique fingerprints

  12. Skin Color depends on3 pigments • Hemoglobin (dermal blood supply) • Reddish tones • Pale, due to? • Bluish (=?), due to? • Melanin • Produced by melanocytes of stratum basale • Carotene • Obtained from plant foods

  13. Melanocytes Function ? Number of melanocytes same in all people, production levels differ !

  14. Papillary layer loose c.t. Reticular layer dense irregular c.t. Dermis

  15. Papillary Layer • Dermal papillae project between epidermal ridges. Consist of • Loose c.t. = _____ • Capillaries • Tactile receptors M

  16. Reticular Layer Consist of • ______________ c.t. • + ?? Pacinian corpuscule (deep pressure)

  17. Hypodermis • 2 other names ? • Indistinct boundary (c.t. fibers interwoven) Made up of • Loose c.t. + lots of . . . Function • Stabilization of skin while allowing for independent movement

  18. Clinical Brief: • Wrinkles • Stretch marks (lineae albicantes) • Decubitus • Transdermal medication • Advantage and disadvantage? • Examples? • Hypodermic needles Lines of cleavage

  19. Accessory Structures: Hair Follicles & Hair • 5 mio hair/hu body. (98% not on top of head) • Three hair types (vellus – intermediate – terminal) • Function ? • Hair color • Growth cycle

  20. Skin Glands: 1) Sebaceous Glands Holocrine Sebum discharged into hair follicles (lubrication & bactericidal) excessive shampooing leads to dry & brittle hair Sebaceous follicles, = Large sebaceous glands, discharge directly to epidermis Where ? Folliculitis; furuncle (boil); acne

  21. 2) Apocrine Sweat Glands • Have merocrine secretion!! • Empty into hair follicle • Location: armpits, groin, nipples • Viscous, cloudy secretion  good nutrient source for bacteria (odor !!) • Secretion may contain Pheromones • Secretion begins at puberty and is stimulated during emotional distress (cold sweat)

  22. 3) Merocrine Sweat Glands • Empty directly onto skin surface • Location: most all over body (esp. abundant on palms & soles: ~ 500/cm2) • Clear, watery secretion (99% H2O; rest NaCl + some waste products) • Sensible perspiration; Function: ?

  23. For purpose of completion: Other integumentary Glands: • Mammary glands: Modified apocrine sweat glands • Ceruminous glands: modified sweat glands in __________

  24. Nails not covered. Skin and Aging Process The End

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