Question

We are able to produce smoothly graded contractions:

Select one:

a. because of feedback from muscle spindles.

b. because muscle fibers are able to fatigue.

c. because the recruitment threshold of large motor neurons is higher than that of smaller motor neurons.

d. because of the action of the tendon jerk reflex.

e. because we have a well-developed sense of will.

Answer 1

We are able to produce smoothly graded contractions-(c) because the recruitment threshold of large motor neurons is higher than that of smaller motor neurons.

Muscle contraction is caused by increasing the number of motor neurons involved which in turn increases the amount of motor units activated in a muscle. This is referred to as recruitment. This is how muscles produce smoothly graded contractions.