Which of the following does not occur when a sarcomerecontracts?
a. the thin filaments are pulled toward the center of thesarcomere
b. the lengths of the thin and thick filaments are unchanged
c. the thin and thick filaments increasingly overlap
d. the distance between the ends of the sarcomeres (Z discs)increases
e. the width of the A band is unchanged
f. the H zone and I band become narrower
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Which of the following would not help a muscle cell torelax?
a. breakdown of acetylcholine by acetylcholinesterase
b. pumping calcium ions from the sarcoplasm into thesarcoplasmic reticulum
c. covering or blocking the myosin-binding sites
d. increasing the flow of sodium ions from the outside(interstitial fluid) to the inside of
    the sarcolemma
e. repolarization of the sarcolemma
