MICROANATOMY

Detailed explanation-1: -The light band is also called the I band, and has a dark midline interruption called the Z disc. The Z disc marks the end of the sarcomere, and is formed by a disc-like membrane. The dark band is also called the A band, and has a lighter central area called the H zone (which contains the M line).

Detailed explanation-2: -The Z disk (or Z line) defines the boundaries of a muscle sarcomere. Two adjacent Z disks along the myofibril mark the boundaries of a single sarcomere. The Z disks are the attachment sites for the thin filaments. Therefore, from each Z disk, thin filaments extend to two neighboring sarcomeres.

Detailed explanation-3: -Z disc-is an area that traverses the I bands and marks the point of the connection between the two neighboring actin filaments. That said, the sarcomere can also be described as the structure between the two Z discs. M line-marks the middle of the sarcomere and contains the protein called myomesin.

Detailed explanation-4: -Z-discs serve three main functions in the sarcomere: (1) stabilizing F-actin filament structures, (2) allowing force transfer between individual sarcomeres, and (3) acting as signaling centers communicating with the nucleus (Clark et al., 2002; Knoll et al., 2011; Sanger and Sanger, 2008).