Connective Tissue

Connective Tissue

1. General

   • Relatively few cells, separated by intercellular substance
     • Ground substance
   • Functions
     • Connection
     • Structural support
     • Protection
     • Transport
     • Insulation
   • All organs supporting specialised tissue
   • Main structures
     • Cells
     • Fibres
     • Ground substance
     • Blood & Lymphatic vessels
     • Nerve fibres

2. Cells

   • Fibroblasts
     • Star-shaped cells
     • Produce
       • Collagen fibres
       • Elastic fibres
       • Ground substance
   • Fat cells
     • Store fat
     • Vary in shape & size
   • Melanocytes
     • Product pigment melanin
   • Macrophages
     • Irregular shaped
     • Many granules in cytoplasm
     • Phagocytic
       • Fixed - Histiocytes
       • Motile - Macrophages
   • Mast cells
     • Produce & store granules containing chemicals
       • Histamine
       • Serotonin
       • Heparin
   • Plasma cells
     • Develop from B-Lymphocytes
     • Produce antibodies
   • Mesenchymal cells
     • All cells of connective tissue derive from this
     • Most abundent in embryo
   • Leucocytes
     • Small number in healthy tissue
       • Increase if damage
     • Main types
       • Neutrophils
       • Lymphocytes

3. Fibres

   • Elastic
     • Yellow fibres
     • Capable of considerable extension and recoil
   • Reticular
     • Very fine, immature collagen fibre
     • Basement layer of epithelium
   • Collagen
     • Long colourless fibres
     • Great tensile strength, resistance to stretching
     • Small degree of flexibility

4. Ground Substance

   • Fluid, jelly-like, rigid
   • Contains fibres
   • Constituents influence properties of tissue
   • Holds cells and fibres together
   • If not fluid - made of large negatively charged molecules
     • Proteoglycans
   • Functions
     • Control movement of water, ion and molecules
     • Structure to tissue
     • Bind connective tissue fibres to eachother

5. Types

   • Areolar
     • Loose textured
     • Mix of all cell & fibre types
     • Rich in ground substance
     • Provides freedom of movement
     • Sites
       • Under skin
       • Between muscles
       • Supporting blood vessels
       • Supporting secretory cells in glands
   • Adipose
     • Mainly fat cells
     • On framework of areolar tissue
     • Close association with blood vessels
     • Functions
       • Energy store
       • Thermal insulation
       • Padding
     • Sites
       • Supporting organs
       • Supporting eyeball
       • Between muscle fibres
       • Under skin
   • Fibrous
     • Bundles of collagen fibres tightly packed
       • Little ground substance
     • Mainly fibroblasts and fibrocytes
       • Lie in rows between fibres
     • White in appearance
     • Regular
       • Collagen fibres in one direction
       • Ligaments, tendons
     • Irregular
       • Irregular interwoven collagen
       • Periosteum, organ capsules
   • Elastic
     • Closely packed elastic fibres
     • Mainly fibroblasts, little ground substance
     • Sites
       • Walls of large arteries
       • Vocal cords
       • Epiglottis
     • Yellow
     • Capable of extension & recoil