Which muscle tissue is characterized by non-striated fibers?

Smooth muscle is characterized by non-striated fibers, which means it lacks the visible banding pattern seen in other muscle tissues. This tissue is typically found in the walls of hollow organs, such as the intestines, blood vessels, and the bladder, where it plays a crucial role in involuntary movements.

The absence of striations in smooth muscle fibers occurs because the arrangement of actin and myosin filaments is different compared to skeletal and cardiac muscle. In smooth muscle, the filaments are organized more randomly, allowing for a contraction that can be sustained over longer periods and varying degrees of contraction.

This feature is essential for its function in regulating internal processes without conscious control, in contrast to skeletal muscle, which has striations, is under voluntary control, and is primarily responsible for movement of the skeleton. Cardiac muscle also has striations but is involuntary, operating under a different mechanism unique to the heart. The term "striated muscle" refers generally to both skeletal and cardiac muscle, both of which exhibit this characteristic. Thus, smooth muscle is the only type among the options that is defined by its non-striated structure.