Summarize the major steps involved in producing a muscle contraction beginning with motor neuron activity and
ending with sarcomere shortening. What will be an ideal response?
ANSWER: Answers should be similar to this. Motor neuron releases ACh into neuromuscular junction.
ACh binds to receptors on the muscle membrane. Muscle produces electrical signal.
Electrical signal passes down the T-tubule and stimulates the sarcoplasmic reticulum to
release calcium. Calcium is the link between excitation and contraction. The calcium binds to
troponin, which in turn causes tropomyosin to change its shape, physically moving out of its
blocking position. Myosin can now attach to the exposed actin binding sites. The binding
triggers the power stroke which produces sarcomere shortening.
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What will be an ideal response?
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