neuromuscular system

• Motor unit


  Nerve impulse + bunch of muscle fibres
• All or none Law

  When a motor unit contracts, either all the fibres will contract or none of them will
• Wave summation


  Repeated nerve impulses with no time to relax, which increases the force of contraction rather than twitches
• Tetanic contraction


  A sustained, powerful contraction
• Spatial summation

  A staggered activation of the motor units to maintain contraction and delay fatigue
• Muscle spindles


  Proprioceptors that detect how far and fast a muscle is being stretched and produce the stretch reflex
• Golgi tendon organs


  Sense the increase in muscle tension and send signals to the brain to allow the antagonist to relax and lengthen
• Autogenic inhibition


  Sudden relaxation of the muscle after high tension
• PNF (Proprioceptive Neuromuscular Facilitation)

  A passive stretch is performed and detected by the muscle spindles so a stretch reflex occurs, the partner then applies resistance to activate the Golgi tendon organs to delay the stretch reflex, the leg then stretches further
• Muscle fibre types


  • Slow oxidative (type 1)
  • Fast oxidative glycolytic (type 11a)
  • Fast glycolytic (type 11b/x)
• Muscle fibre types


  • Contraction speed: slow, fast, fast
  • Force produced: low, high, high
  • Fatiguability: low, medium, high
  • Mitochondrial density: high, medium, low
  • Myoglobin content: high, medium, low
  • Capillary density: high, medium, low
  • Aerobic capacity: high, medium, low
  • Anaerobic capacity: low, medium, high
  • Glycogen store: low, medium, high
  • Colour: red, pink, white
• Neurone size: type I small, type IIa large, type IIb/x large