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HMS, BM EQ-Bank 34

Outline TWO structural characteristics of slow twitch muscle fibres.  (3 marks)

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Answers could include TWO of the following:

Slow twitch fibres have:

  • Abundant mitochondria
    • They contain numerous mitochondria throughout the muscle fibre to support aerobic metabolism.
    • These organelles enable efficient ATP production through oxidative pathways, allowing sustained energy generation for prolonged endurance activities.
  • Rich blood supply:
    • Possess an extensive capillary network surrounding each fibre, providing continuous oxygen delivery for aerobic respiration.
    • This vascular density supports the high oxygen demands of endurance activities and contributes to their red appearance.
  • High myoglobin content:
    • Store significant amounts of myoglobin, an oxygen-binding protein within the muscle fibres.
    • This gives them their characteristic red colour and provides an oxygen reserve for sustained aerobic metabolism during prolonged activities.
  • Smaller diameter:
    • Slow twitch fibres have a smaller cross-sectional area compared to fast-twitch fibres.
    • While this limits maximum force production, the smaller size allows for more efficient oxygen diffusion throughout the fibre, enhancing endurance capacity.
Show Worked Solution

Answers could include TWO of the following:

Slow twitch fibres have:

  • Abundant mitochondria
    • They contain numerous mitochondria throughout the muscle fibre to support aerobic metabolism.
    • These organelles enable efficient ATP production through oxidative pathways, allowing sustained energy generation for prolonged endurance activities.
  • Rich blood supply:
    • Possess an extensive capillary network surrounding each fibre, providing continuous oxygen delivery for aerobic respiration.
    • This vascular density supports the high oxygen demands of endurance activities and contributes to their red appearance.
  • High myoglobin content:
    • Store significant amounts of myoglobin, an oxygen-binding protein within the muscle fibres.
    • This gives them their characteristic red colour and provides an oxygen reserve for sustained aerobic metabolism during prolonged activities.
  • Smaller diameter:
    • Slow twitch fibres have a smaller cross-sectional area compared to fast-twitch fibres.
    • While this limits maximum force production, the smaller size allows for more efficient oxygen diffusion throughout the fibre, enhancing endurance capacity.