motor units

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  • Created by: Zina_
  • Created on: 30-04-18 14:55
what is a motor unit?
functional element of a muscle compromising of an alpha motor neuron and the group of muscle fibres the neuron innervates
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how do muscles control limb movements?
neurons in ventral horn of the spinal cord, axons leave ventral to the periphery via peripheral neurons,each neuron branches to specific fibre, AP in neuron stimulates contraction in all fibres of the unit
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what does low unit freq stimulation cause?
single isolated twitches
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what does inc unit freq stimulation cause?
somation = unfused tetanus
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what does 30-40 max unit freq stimulation cause?
fused tetanus, complete max tetanus force
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how do muscle units differ depending on function of the muscle?
muscle requiring fine skilled movements has large number of motor units with few muscle fibres/ muscles requiring large amount of force have units composed of large number of fibres
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what is the physiological properties of a slow motor unit?
well vascularised, oxidative metabolism, small amount of force
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what is the physiologyical properties of a fatigue resistant motor unit?
oxidative metabolism, may also respire glycolytically, inc force, less resistant to fatigue
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what is the physiological properties of a fast fatigue motor unit?
poorly vascularised, respires through glycolysis, max force, quick to fatigue
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Card 2

Front

how do muscles control limb movements?

Back

neurons in ventral horn of the spinal cord, axons leave ventral to the periphery via peripheral neurons,each neuron branches to specific fibre, AP in neuron stimulates contraction in all fibres of the unit

Card 3

Front

what does low unit freq stimulation cause?

Back

Preview of the front of card 3

Card 4

Front

what does inc unit freq stimulation cause?

Back

Preview of the front of card 4

Card 5

Front

what does 30-40 max unit freq stimulation cause?

Back

Preview of the front of card 5
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