A & P chapter 5

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A & P chapter 5
2012-09-29 17:33:38
Integumentary System

Integumentary System
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  1. Structures of the integument
    • Skin
    • Hair
    • Nails
    • Glands
  2. Functions of the integumentary system
    • Protection
    • Sensation
    • Temperature regulation
    • Vitamin D production
    • Excretion
    • Immunity
  3. Epidermis:
    Subcutaneous tissue:
    • Epidermis: superficial layer of epithelial tissue
    • Dermis: deep layer of connective tissue
    •     -structural strength
    • Subcutaneous tissue:
    •     -not part of skin
    •     -loose connective tissue that connects skin to underlying   muscle or bone
  4. Epidermis
    • -Avascular; nourished by diffusion from capillaries of the papillary layer of the dermis
    • -Composed of cells arranged into layers, or strata
    • -Separated from dermis by basement membrane
  5. Epidermal cell types
    • Keratinocytes: most cells. Produce keratin for strength and durability.  Give epidermis its ability to resist abrasion and reduce water loss.
    • Melanocytes: contribute to skin color.  Melanin produced by these cells then trasferred to keratinocytes.  Same number of melanocytes in all people.
    • Langerhan's cells: part of the immune system
    • Merkel's cells: associated with nerve endings, detect light, touch, and superficial pressure
  6. Desquamate
    cells of the deeper layers undergo mitosis; as they move toward the surface, older cells slough off
  7. Keratinization
    As cells move outward through the layers they fill with keratin, die, and serve as a layer that resists abrasion and forms permeability layer.
  8. Epidermal strata
    Stratum basale (germinitivum)
    Stratum spinosum
    Stratum granulosum
    Stratum lucidum
    Stratum corneum
    • Stratum Basale: deepest portion of epidermis and single layer.  High mitotic activity and cells become keratinized
    • Stratum Spinosum: limited cell division. Desmosomes break apart and new desmosomes form.  Additional keratin fibers & lamellar bodies (lipid-filled, membrane bound organelles) form inside keratinocytes...limited cell division takes place in the S.S.  Mitosis does not occur in the more superficial strata
    • Stratum granulosum: contains keratohyalin (nonmembranebound protein granules).  In superficial layers nucleus and other organelles degenerate and cell dies.
    • Stratum lucidum: thin, clear zone.  Found only in palms and soles.
    • Stratum corneum: most superficial. Consists of cornified cells.
  9. Epidermal layers and keratinization
    Cells move from deep to superficial
    • 1. In the stratum basale, cells divide by mitosis & some of the newly formed cells become the cells of the more superficial strata.
    • 2. In the stratum spinosum, keratin fibers and lamellar bodies accumulate.
    • 3. In the stratum granulosum, keratohyalin granules accumulate, & a hard protein envelope forms beneath the plasma membrane; lamellar bodies release lipids; cells die.
    • 4. In the stratum lucidum, the cells are dead and contain dispersed keratohyalin.
    • 5. In the stratum corneum, the dead cells have a hard protein envelop, contain keratin, and are surrounded by lipids.
  10. Thick Skin
    • -Has all 5 epithelial strata
    • -Found in areas subject to pressure or friction (palms, fingertips, soles of feet)
    • -fingerprints and footprints.  Papillae of underlying dermis in parallel rows.
  11. Thin Skin
    • -More flexible than thick skin
    • -Hair grows here
  12. Callus & Corn
    Callus: increase in number of layers in stratum corneum.  When this occurs over a bony prominence, a corn forms.
  13. Skin color determined by what 3 factors?
    • -Pigments
    • -Blood circulating through the skin,
    • -Thickness of stratum corneum
  14. Skin color: pigments
    (Melanin, melanocytes, Albinism, carotene)
    • Melanin: provides for protection against UV light.  Group of chemicals derived from aa tyrosine.  Colored brown to black, may be yellowish or reddish.
    • Melanocytes: produces melanin. Processes extend between keratinocytes of the stratum basale and the stratum spinosum.
    • Albinism: deficiency or absense of pigment.  Production determined by genetics, hormones, exposure to light.
    • Carotene: yellow pigment. From vegetables. Accumulates in stratum corneum, in adipose cells of dermis and in subcutaneous tissue. 
  15. Skin Color cont.
    • Blood circulating through the skin
    • -imparts reddish hue and increases during blushing, anger, inflammation
    • -Cyanosis: blue color caused by decrease in blood oxygen content

    • Thickness of stratum corneum
    • -thicker areas can be yellowish
  16. Dermis
    • -Gives structural strength. Connective tissue with many fibers, fibroblasts, macrophages.  Some adipocytes and blood vessels.
    • -Contains nerves, blood vessels, hair follicles, smooth muscles, glands, and lymphatic vessels.
    • -Sensory functions: pain, itch, tickle, temperature, touch, pressure, two-point discrimination.
  17. 2 layers of the Dermis
    Papillary: superficial. 1/5. Areolar with lots of elastic fibers.  Dermal papillae, capillary beds. Fingerprints. Whorls of ridges. Touch receptors (Meissner's), free nerve endings sensing pain

    Reticular: deep 4/5. Dense irregular connective tissue. Collagen and elastic fibers.  In the figure see: some adipose, hair follicles, nerves, oil glands, ducts of sweat glands, heat sensors.