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Neuromuscular Junction

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Nervous System

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Action Potential

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Muscle Control

  • nerves run from spinal cord to muscles
  • nerves connect to muscles at neuromuscular junction

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Brain → Spinal Cord → Muscles

  • Brain decides
  • Spinal cord receives message from brain
  • Spinal cord sends impulse to the muscle

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Neuromuscular Junction

Nerve impulse from the spine travels to neuromuscular junction and stimulates release of neurotransmitter ACh

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Neuromuscular Junction

  • ACh gets released into synaptic cleft via exocytosis
  • ACh then binds to receptors which stimulates muscle impulse

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Muscle Impulse ---> Muscle Contraction

Muscle Impulse triggers the release of Ca ions into muscle cytosol

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Muscle Impulse ---> Muscle Contraction?

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How does Ca cause muscle to contract?

Ca binds and changes shape of binding site, allowing myosin heads to bind to actin

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Now What?

ATP binds to actin myosin complex and causes myosin heads to contract

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Actin and Myosin

  • actin = the rope
  • myosin = the hands on the rope
  • powered by ATP

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Muscle Shortening

Each band shortening causes the whole muscle to shorten

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Flexion

  • muscle shortens and pulls radius up
  • causes flexion