KINE 2011 Lecture Notes - Lecture 17: Motor Neuron, University Of Manchester, Motor Unit
17 Sep 2017
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Action potential lasts 1-2 msec: no mechanical activity during action potential. Mechanical activity following action potential lasts for ~100 msec. Contraction time: going through the cross-bridge cycles, going towards peek (pulling actin towards center). Relaxation time: brought binding sites and the myosin lets go, the actin must slip back. Contractile response; both contraction time and relaxation time that follows one action potential. Single action potential causes a brief and weak contraction = muscle twitch. 1 twitch doesn"t have any real effect on the muscle. Motor unit = one motor neuron and all the myofibre it innervates. Size of motor units (how many myofibre are innervated by one motor neuron) varies depending on muscle. Motor neuron if it based on all the signals from cns, an action potential is released, it then releases acetyl colane that starts the contraction process. Action potential comes to all the axons, releases acetyl co. More cells in one motor unit, means stronger.
