One of the reasons you might struggle to lift a heavy object with your arm fully extended is because

A.  in extension, the proximity of Z discs to thick filaments restricts the sliding  movement within sarcomeres.
B.  full extension results in decreased overlap between thick and thin filaments in the muscle.
C.  in that posture, some  myosin heads overlap actin in the wrong orientation and  tug actin in the wrong direction.
D.  motor neurons cannot release as much ACh in that posture.


B

Anatomy & Physiology

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Fill in the blank(s) with the appropriate word(s).

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