Epithelium tissues

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  • Created by: Saoirse
  • Created on: 22-10-14 14:49

Tissues form all the organs in the body and work together to accomplish a physiological function. Many organs form a system.

 There are 4 types of tissue;

    • Epithelial
    • Connective
    • Muscle
    • Nervous

There are 2 types of epithelium tissue:

  • Membranous epithelium:
    • Found: skin, lining cavities, tubes, ducts and the viscera
    • Role: protection from pathogens, physical injury, toxins and dehydration
    • Always has a free surface exposed to; gases (in lungs), liquids (blood vessels), semi solids (in the gut) and urine (bladder)
    • Cells continually regenerate to replace dead or damaged cells
  • Glandular epithelium:
    • Found in the secretion portion of glands (thyroid, adrenal and sweat glands)

Features of epithelial tissue

    • Closely packed cells forming continuous sheets
    • Cells sit on a basement membrane
    • Have an apical (upper) free surface
    • Avascular (without blood vessels) so nutrients diffuse in from underlying connective tissue
    • Good nerve supply
    • Rapid cell division

Naming epithelium

  • Number of cell layers:
    • Simple = 1
    • Stratified = more than 1
    • Pseudostratified = single layer that looks like more as the cells all reach the apical surface and nuclei are found at different levels
  • Shape of cells
    • Squamous= flat squares
    • Cuboidal = cube like
    • Columnar = tall and thin columns
    • Transitional = shape varies with stretching tissue


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