1. Functions of the skin
    barrier system (water, microorganisms, UV light), thermoregulation, plasticity, elasticity
  2. three layers of skin
    dermis, epidermis, hypodermis (subcutaneous tissue)
  3. skin types
    thick skin (hands, soles of feet), thin skin (everywhere else)
  4. layers of the epithelium
    stratum basale, spinosum, granulosum, lucidum, corneum
  5. stratum basale description/function
    single layer of cuboidal cells forming the basal layer sitting on the basement membrane. function - intense mitotic division for use in skin
  6. stratum spinosum description/function
    filled with keratin and desmosomes to bind cells tightly together (f - resists abrasion)
  7. stratum granulosum description/function
    3-5 layers squamous cells that secrete lipid rich cellular "cement" (cements/seals skin)
  8. stratum lucidum
    more in thick skin, translucent layer packed with keratin and no organelles (resists abrasion)
  9. stratum corneum
    the "dead layer," a layer of organelleless keratinized cells that slough off constantly (desquamation)
  10. cell types of skin
    keratinocytes (cell in any/all layers), melanocytes (UV protection), langerhans (immunity)
  11. melanocytes
    synthesize melanin in deeper layers of skin
  12. melanocytes and skin color
    melanocyte number constant, melanin granule count not constant. When tanning, melanocytes create more melanin granules and existing granules become darker
  13. langerhans
    macrophages of the skin regions. Found in basale and spinosum, bone marrow derived, can bind/present antigens for immunity building
  14. dermis - subcutaneous layer - definition
    aka hypodermis and superficial fascia, fat cells, neurovascular networks, loose CT binding underlying structures
  15. epithelial glands
    holocrine (entire contents of cell), merocrine (exocytosis), apocrine (a portion of cytosol released)
  16. sebaceous glands
    epithelial cells with sebum (lipids) conc. in face/scalp. secrete sebum onto hair follicles for anti fungal, bacteria
  17. sebaceous glands - mechanism
    they release the sebum along with dead cells, basal layer of gland regenerates cells
  18. merocrine sweat glands - description
    coiled glands that release sweat onto skin surface (thermoregulation)
  19. apocrine sweat glands
    release viscous odorless fluid that smells when bacteria digest it. Released in armpits, anus, genitals
  20. nails
    nail bed is spinosum and basale only, modified epithelium, cuticle is stratum corneum
  21. hair follicle
    epidermis invagination, dermal papilla contains cells for growth and blood supply, arrector pillae = goosebumps, melanocytes provide pigment
  22. hair growth cycles
    catagen (2-3 week phase of no growth), anagen (growth phase 30days to 6 years), telogen (resting phase, no growth, possible hair loss)
  23. aging effects on skin
    decreased elasticity, atrophy of strata, reduced sweating
  24. blood flow to skin
    • during activity - less, shunted to muscles except altered in hot environments
    • during rest - is allowed more
  25. effects of activity on skin
    hyperplasia (callous) increased sweat ability, blisters (fluid deposition between dermis, epidermis by excessive shearing)
  26. effects of immobilization
    skin breakdown (decubitus ulcer) at bony prominences (heels, sacrum, greater trochanter, scapula, elbows, back of head)
Card Set
Covering the fourth histo PP presentation