ANATOMY

Detailed explanation-1: -I bands are composed of thin actin filaments and proteins that bind actin and they are bisected by the Z line. The thin filaments extend in each direction from the Z-disk, where they do not overlap the thick filaments, they create the light I band.

Detailed explanation-2: -The sarcomere is split into the H-zone, A-band, I-band, M line and Z line. The H-zone consists of myosin only, the I-band consists of actin only and the A-band contains both actin and myosin. The M-line holds together the thick myosin filaments.

Detailed explanation-3: -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-4: -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.