ANATOMY

Detailed explanation-1: -The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments. The myosin and actin filaments overlap in peripheral regions of the A band, whereas a middle region (called the H zone) contains only myosin.

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: -Actin filaments extend from this region and are joined together by several complex protein structures. The M-line is the middle of the sarcomere, marking the central point of the myosin filaments. The I-band consists of actin filaments that are not overlapped by myosin; this region contains the Z-disc.

Detailed explanation-5: -Actin filaments are particularly abundant beneath the plasma membrane, where they form a network that provides mechanical support, determines cell shape, and allows movement of the cell surface, thereby enabling cells to migrate, engulf particles, and divide.