Relationship between myocardial sarcomere length and tension

Top panel (A) is a schematic of a sarcomere. The thin filaments (actin, shown in black) are attached at the Z band. The length of two actin filaments as they extend from the Z band is indicated by "b." The length of a thick filament (myosin, shown in maroon) is denoted by "a." Panels B and C show the correlation between sarcomere stretch and tension. Position number 1 shows extreme sarcomere stretch (as occurs in the volume-overloaded ventricle) where neither actin filament can interact with the myosin filament; as a result, tension development is 0. Points 2 and 3 demonstrate situations of maximum actin myosin overlap with maximal tension production.