Muscles

• Slow twitch fibres

  • Mainly aerobic respiration
  • reddish colour -> lots of myoglobin + capilleries
  • lots of mitochndria
  • can carry out long periods of mild activity -> fatigue resistant
  • few sarcoplasmic reticulum
  • low glycogen content, as have more capilleries to supply glucose
• Fast twitch fibres

  • Mainly anaerobic respiration
  • whittish colour -> few capilleries
  • fatigues quickly
  • little mitochondria
  • high sarcoplasmic reticulum -> quickly releases Ca2+ - muscle contraction
  • high glycogen content, store of glucose, can be used in respiration, ATP for muscle contraction