Explain mechanism of muscle contraction in 120-150 words.


Muscle contraction takes place in following steps:
  • Nerve impulse travels through a motor nerve to its endpoints on muscle fibers.
  • A little amount of acetylcholine (neurotransmitter) is secreted on the fiber from the nerve ending.
  • The membranes of muscle fiber open up by the action of acetylcholine.
  • The sodium ions enter inside the membrane through this opening.
  • The sodium channels also get opened.
  • This initiates action potential inside the membrane.
  • The action potential runs along the muscle fiber
  • Due to this action potential the sarcoplasm releases calcium ions.
  • These calcium ions result in attractive forces between actin and myosin filaments of muscles that cause contraction.


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