ANATOMY

Detailed explanation-1: -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.

Detailed explanation-2: -The anisotropic band contains both thick and thin filaments. Within the A-band is a paler region called the H-zone (from the German “heller", brighter). Named for their lighter appearance under a polarization microscope.

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. Z disc: it is the area where two actin filaments connect and transverse the I bands.

Detailed explanation-4: -An individual sarcomere contains many parallel actin (thin) and myosin (thick) filaments. The interaction of myosin and actin proteins is at the core of our current understanding of sarcomere shortening.

Detailed explanation-5: -The myofibrils contain thick and thin filaments. The arrangement of thick myosin filaments along the myofibrils and the cell cause them to refract light and produce a dark band which is known as an A band. The anisotropic band is composed of both thick and thin filaments.