Question

When there is a resistance to the movement produced by a given limb muscle, A) gamma motor neurons are inhibited by higher brain centers. B) there is a decrease in the amount of force generated by extrafusal muscle fibers. C) the muscle involved in the movement immediately shortens when stimulated. D) intrafusal fibers receive fewer action potentials from the gamma motor neurons. E) muscle tone is increased and more motor units are recruited to the contraction.

Answer 1

The correct answer is option E.

Muscles contract when stimulated by electrical impulses from motor neurons, which are controlled by the brain. When there is resistance to movement, the brain sends more motor unit commands, resulting in an increase in muscle tone and the recruitment of additional motor units, or muscles, to assist in the contraction.

The other options are either incorrect or are not specific enough.