MUSCLE PHYSIOLOGY

Detailed explanation-1: -The Z-band (or Z-disk) is a dense fibrous structure made of actin, -actinin, and other proteins. Thin filaments (or actin filament) are anchored at one end at the Z-band. Titin is anchored to both the Z-band and the M-line. Thick filaments are anchored in the middle of the sarcomere at the M-line.

Detailed explanation-2: -An essential and major component of the Z-disc, -actinin, is responsible for cross-linking actin filaments as well as anchoring the protein Titin, which controls sarcomere length.

Detailed explanation-3: -Titin anchors myosin filaments to the Z-disc, and two titin molecules connect to each actin filament within the Z-disc [24]. Because the ratio of actin to myosin filaments is 2 : 1 in regular overlap (figure 3a, cross section **), the ratio of titin proteins to myosin filaments is 4 : 1.

Detailed explanation-4: -A sarcomere is defined as the segment between two neighbouring Z-lines (or Z-discs). In electron micrographs of cross-striated muscle, the Z-line (from the German “zwischen” meaning between) appears in between the I-bands as a dark line that anchors the actin myofilaments.