Tissues Epithelial by lanyuehua

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									            Tissues




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Cells
  Tissues
      Organs
        Organ systems
          Organisms




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                   Tissues
   Groups of cells with a common structure
    and function—similar cells work together
    at one job.




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            Epithelial Tissues




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            Introductory Questions
 What is the function of epithelial tissue?
 List some locations in which it is found.




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                 Epithelial Overview
 General definition
 Structure
 Function
 Types
  Simple
             Squamous, cuboidal, columnar
     Stratified
             Squamous, columnar, transitional

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It takes about 27
days for the
outer lay of skin
to shed and be
replaced; that
works out to 1.5
pounds of skin
cells per year.

Where
does all
the dead
skin you
shed go?
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                Epithelial Tissues
   Structure
Tightly-packed cells
Little material between cells
Cover or line organs or body
   cavities
Has free side
Basement layer—non-living
   and separates epithelial
   from underlying
   connective tissue


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                Epithelial – Structure
     – Classified by:
             1) Number of layers
               – Simple – single layer
               – Stratified – multiple
                 layers




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                  Epithelial – Structure
            Classified by:
            2) Shape of cells
            Squamous – fried egg,
              tiles
            Cuboidal – cube
            Columnar - brick




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                     Epithelial Tissues
   Function
Protective—Barrier to:
         -water loss
         -microbes
         -mechanical
         injury
    --Secretion
    --Absorption
    --Sensory
        reception
    --Movement
            -Cilia




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                Types of Epithelial Cells
   1) Simple
     A) Squamous
            Single layer
            Flat cells
            Passage ways such as
              lungs, arteries,
              mesentary
            Places of diffusion &
              secretion—alveoli,
              capillaries, lymph vessels




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        Types of Epithelial—Simple
     – B) Cuboidal
               Single layer
               Cube-shaped
               Covers and lines
               Forms tubes/glands
                 – Pancreas, kidney,
                   salivary glands




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        Types of Epithelial—Simple
     – C) Columnar
             Single Layer – nuclei
              often on same level
             Tall, elongated cells
             Lining tissues
                – Digestive, uterine
             Secretion – goblet cells
              secrete protective
              mucus




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                     Types of Epithelial
   2) Stratified
   A) Squamous
     – Layered
     – Often keratinized (protein
       hardens—water stays
       inside & chemicals &
       microorg. kept out)
     – Areas of high stress
             Mouth, rectum, vagina,
              outermost skin




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The ink of tattoos must be injected
below the basement membrane.




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     Types of Epithelial—Stratified
   B) Transitional
     –      Many cells thick
     –      Elastic
     –      Bladder, ureters
     –      Appearance
              Stretched or relaxed




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     Types of Epithelial—Stratified
   C) Columnar, pseudo-
    stratified
     – Appears layered due
       to nuclei on multiple
       layers
     – Often ciliated
             Moves product
             Respiratory tract
             Fallopian tubes
     – Goblet cells secrete
       mucus & cilia sweeps
       away.

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            http://www.youtube.com/watch?v=7z2vYr
            5YjD8




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