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• Four major types

  1. Epithelial

  2. Connective (many components)

  3. Muscle

  4. Nervous
• EPITHELIAL TISSUES

  CHARACTERISTICS

   Cells are closely

  packed without any

  intercellular spaces

   Lie on basement

  membrane
• General characteristics of epithelial tissues:

  • Cover organs and the body
  • Line body cavities
  • Line hollow organs
  • Have a free surface
  • Have a basement membrane
  • Avascular
  • Cells readily divide
  • Cells tightly packed
  • Cells often have desmosomes
  • Function in protection, secretion, absorption, and excretion
  • Classified according to cell shape and number of cell layers
• Types of simple epithelium tissues:

  Simple squamous:

  • Single layer of flat cells
  • Substances pass easily through
  • Line air sacs
  • Line blood vessels
  • Line lymphatic vessels

  Simple cuboidal:

  • Single layer of cube-shaped cells
  • Line kidney tubules
  • Cover ovaries
  • Line ducts of some glands

  Simple columnar:

  • Single layer of elongated cells
  • Nuclei usually near the basement membrane at the same level
  • Sometimes possess cilia
  • Sometimes possess microvilli
  • Often have goblet cells
  • Line uterus, stomach, intestines

  Pseudostratified columnar:

  • Single layer of elongated cells
• Different types of simple epithelium tissue:

  Squamous epithelium:

  • Cells are thin, flat, irregular cells which fit like floor tiles to form delicate lining called Pavement epithelium
  • Nuclei in the centre
  • Found in the oesophagus, lining of the mouth, alveoli of the lungs, blood vessels
  • Protects the underlying tissue from injury germs
  • Exchange of gases in lungs and materials between cells and blood