Energy in muscle cells

• During vigorous exercise


  Oxygen debt builds up
• Oxygen debt


  Repaid once muscles come to rest and oxygen is available
• ATP converts to prevent the citric acid cycle and electron transfer chain, so cells have to rely on ATP produced by glycolysis
• Glycolysis produces 2 ATP and 2 NADH when hydrogen bonds to NAD
• lactate is converted back to pyruvate and glucose when o2 is available again - at rest
• Anaerobic respiration involves glycolysis followed by fermentation, resulting in the production of lactic acid or ethanol as end products.
• Slow twitch

  • slow long contractions
  • becomes slowly fatigued
  • fat storage used
  • glycolysis and aerobic pathways
  • large number of mitochondria present
  • high concentration of myoglobin in cells
  • high density of blood capillaries
  • e.g - endurance, back posture
• Lactic acid buildup can cause fatigue during intense exercise.
• Fermentation occurs when there is not enough oxygen present to complete aerobic respiration.
• Fast twitch

  • fast, short contractions
  • quickly fatigued
  • glycogen storage
  • glycolysis only
  • small number of mitochondria
  • low density of blood capillaries
  • low concentration of myoglobin
  • e.g - power activities, eye movement
• Myoglobin


  A protein which can store oxygen in muscle cells, and has a stronger affinity for oxygen than haemoglobin
• Myoglobin


  • Can extract oxygen from blood for use in muscle cells
• Myoglobin is a protein
• Myoglobin can store oxygen in muscle cells
• Myoglobin has a stronger affinity for oxygen than haemoglobin
• Myoglobin can extract oxygen from blood for use in muscle cells
• Muscle cells have a small number of mitochondria
• Muscle cells store 99% of their energy as glycogen