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Skin Notes

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					                   Ch 5 Skin & Integumentary System


Skin maintains homeostasis by:
       *providing protective covering
       *regulating body temperature
       *retarding water loss
       *housing sensory receptors
       *synthesizing biochemicals
       *excreting wastes


Skin has 2 layers:
     (1) epidermis
     (2) dermis
Subcutaneous layer is below skin.

                                        EPIDERMIS

*Stratified Squamous Epithelium
*Lacks Blood Vessels
Keratinization - older cells that are pushed to the surface
       harden when their cytoplasm fills with tough
       water-proof protein called keratin
Stratum Corneum is layer of tightly packed dead cells
     in outermost epidermis.

Calluses are thickened areas caused by cell growth
      stimulated by rubbing or pressing.

Skin color is affected by melanin production, blood flow,
      diet, and biochemical imbalances.
melanin
      -produced by melanocytes
      -absorbs UV radiation to prevent DNA mutations
      -all people have same # of melanocytes
      -abundant melanin production determines skin color
                               DERMIS

*Connective tissue with collagen and elastic fibers
*Epithelial tissue
*Muscle tissue
*Nervous tissue
*Blood vessels supply nutrients to skin cells and
     help to regulate body temperature.
*Dense connective tissue binds epidermis to
     underlying tissues.

Nerve Cell Processes:
    (1) Motor processes carry signals from brain or
          spinal cord (SC) to dermal tissues and glands.
    (2) Sensory processes carry signals from
          specialized receptors to brain or SC.

               SUBCUTANEOUS

*Adipose tissue insulates
*Loose connective tissue binds skin to underlying organs
*Major blood vessels feed skin and adipose tissue
*Collagenous and elastic fibers are continuous with
      those of the dermis so there is no sharp boundary
      to separate the "layers"

				
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posted:11/13/2011
language:English
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