MEDICAL PHYSIOLOGY

Detailed explanation-1: -The actin filaments are attached at their plus ends to the Z disc, which includes the crosslinking protein -actinin. The myosin filaments are anchored at the M line in the middle of the sarcomere .

Detailed explanation-2: -Sarcomere ends, called Z-lines, are marked by electron-dense structures that serve as anchor sites for actin-based thin filaments, while the sarcomere center, or M-line, is characterized by a similar anchoring structure for bipolar myosin-based thick filaments (Figure 1).

Detailed explanation-3: -The Z disc serves to anchor the thin filaments to adjacent sarcomeres.

Detailed explanation-4: -At the Z-disc the barbed ends of the antiparallel actin filaments from adjoining sarcomeres interdigitate and are crosslinked primarily by layers of -actinin.

Detailed explanation-5: -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).