MUSCLE PHYSIOLOGY

Detailed explanation-1: -Smooth muscle cell contraction squeezes the cell from every direction since the myofibrils are not arranged in a pattern as in other muscles. Hence, light and dark bands are absent in smooth muscles.

Detailed explanation-2: -Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (bands or stripes).

Detailed explanation-3: -The light bands are called I bands and contain only thin filaments. The dark bands are called A bands and contain thick and thin filaments, with the thick filaments running the entire length of the A band. Thus the length of the thick filament determines the length of the A band.