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ageing - Coggle Diagram

- - - - types
        
        extracellular
        
        Vitamin E
        
        intracellular
        
        superoxide dismutase, catalase
- - - - death
- - - - nature
        
        high sensitivity
        
        short half-life
        
        propagate chain reactions
      - types
        
        hydroxyl radical (OH black dot)
        
        superoxide radical (O2 black dot)
        
        Nitric oxide (NO black dot)
      - sources
        
        phagocytic cells
        
        ionising radiation
        
        smoking
        
        oxidation-reduction reactions
        
        hyperglycaemia
      - Damage
        
        DNA/RNA
        
        Proteins
        
        enzymes
        
        membrane lipids
        
        cells
      - free radicals in ageing
        
        increased free radical damage withage
        
        decreased antioxidant defences with age
    - - elderly are susceptible because
        
        decreased glucose tolerance
        
        increased incidence of diabetes
      - effects on proteins
        
        increased cross-linking
        
        increased fluorescence
        
        altered of activity of enezymes
        
        altered immunogenicity
        
        alterd half-life
        
        altered recognition by receptor
    - - lipofuscin (lipid-rich pigment)
        
        produced by membranes/organelles or free radical peroxidation
        
        effects - unknown
    - - theory
        
        abnormal proteins produced by random errors of transcription and translation
        
        accumulation of abnormal proteins impairs cellular function
  - - - number of cell divisions is fixed (hayflick limit)
      - limit not affected by external environment
      - cells can memorise divisions undertaken
      - telomeres shorten and limit cell division
      - telomerase can extend cellular divisions
    - - errors in replication of DNA which are not repaired will affect viability of cells
      - repair systems for DNA decrease with age