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Action potential and strength of muscle contraction?

  1. Apr 3, 2010 #1
    Hello guys,

    Although the response of a motor unit is all-or-none, the strength of the response of the entire muscle is determined by the number of motor units activated. Nerve impulses passing down a single motor neuron will thus trigger contraction in all the muscle fibers at which the branches of that neuron terminate. and this is a motor unit.

    1.My question is some organs are supplied only with one motor neuron, is it impossible for them to control the strength of their contraction?
    2.Also this is just about the central nervous system. Since CVS has many nerves which are branches of other nerves, when an action potential is sent how come this action potential doesn't travel through the branches and innervate unnessecary structures?

    Thanks for anyone who is going to help :smile:
  2. jcsd
  3. Apr 7, 2010 #2


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    1/ No.
    2/ idem.
  4. Apr 7, 2010 #3


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    I think you're confusing the terms nerve and neuron.

    A nerve is a bundle of neuron axons (surrounded by endoneurium, perineurium and epineurium, which are connective tissue layers that hold them together). You don't have a single NEURON innervating an organ, but you may have a single NERVE innervating it, with MANY neurons.

    Also, as soon as you're talking about nerves, by definition, you're talking about the peripheral nervous system, not the central nervous system, so your second question doesn't make sense to me.
  5. Apr 7, 2010 #4
    Yes you are absolutely correct. I went back and read from scratch about nerves,neurones and connective tissue you talked about and worked it out. Thanks for the help :smile:
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