Question

select the correct answer.
a skeletal muscle is a composition of several components bundled one into the other. at which structural level in the muscle does contraction occur to bring about contraction in the whole muscle?
a. myofibri
b. muscle fiber
c. myoneural junction
d. tendon
e. fascicle

Explanation:

Muscle contraction occurs at the level of the myofibril. Myofibrils are the basic units within muscle fibers that contain the contractile proteins (actin and myosin). When a muscle is stimulated to contract, it is the myofibrils within the muscle fibers that undergo the sliding - filament mechanism (where actin and myosin filaments slide past each other) to cause contraction. A muscle fiber (B) is a single muscle cell that contains many myofibrils. A fascicle (E) is a bundle of muscle fibers. A tendon (D) is a connective tissue that attaches muscle to bone. The myoneural junction (C) is the synapse between a motor neuron and a muscle fiber, which is involved in the initiation of muscle contraction (by transmitting the nerve impulse to the muscle fiber) but not the actual site of contraction within the muscle.

Answer:

A. myofibri