Question

Smooth muscles are
A. Involuntary, cylindrical, striated
B. Voluntary, spindle-shaped, uninucleate
C. Involuntary, fusiform, non-striated
D. Voluntary, multinucleate, cylindrical

Answer 1

Hint: 1)Smooth muscles are a class of muscle which are associated with various organ systems.
2)They exert pressure by contracting movements.

Complete answer:
Option A: The actin and myosin filaments of smooth muscle are arranged as stacked patterns across the cell. Smooth muscle appears without striation because of this. This staircase-like arrangement is different from that of cardiac muscle and skeletal muscle in which the actin filaments are attached to the Z band and appear as distinct striated patterns. Also, smooth muscles are not cylindrical. They are involuntary muscles and this is the only correct point among the three. Therefore, this is the incorrect option.

Option B: Voluntary muscles are those which can be controlled by our will. Smooth muscles are involuntary muscles. Their movements cannot be controlled consciously. Smooth muscles are uninucleate and spindle-shaped, but not voluntary. Therefore, this is the incorrect option.

Option C: Smooth muscles are involuntary muscles. They are associated with slow and regular contraction and relaxation patterns of movement. Fusiform muscles are spindle-shaped muscles where muscle fibers are arranged parallelly. Smooth muscle cells are fusiform. This increases the degree of contraction of the muscle. Also, smooth muscles are non striated. Therefore this is the correct answer.

Option D: Smooth muscles are not voluntary muscles. They are composed of uni-nucleated unbranded cells. They are not cylindrical but spindle. All three characteristics are wrong. Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: 1)The fusiform structure of the muscle increases the range of contraction of the muscle. Therefore they can perform strong movements.
2)The cardiac muscle is an example of an uninucleate muscle. Whereas skeletal muscles are multinucleated.