MUSCLE PHYSIOLOGY

Detailed explanation-1: -A bands (or anisotropic bands): It is also called the dark band and contains the whole thick filament (myosin). I bands (or isotropic bands): it is called the light band that contains only the thin filament (actin). The thin filament lies between the two thick filaments.

Detailed explanation-2: -The I band consists of actin-based thin filaments; these filaments also extend into the AI band, where they overlap with the thick filaments, which explains why the AI bands appear darker than the H zone (where only thick filaments are present).

Detailed explanation-3: -The striated appearance of skeletal muscle tissue is a result of repeating bands of the proteins actin and myosin that are present along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes the entire cell to appear striated or banded.