MEDICAL PHYSIOLOGY

Detailed explanation-1: -The myosin heads are known as cross-bridges because they can bind to and move along actin in the thin filament. It is this actin-myosin interaction that is the molecular basis for force generation and movement in muscle cells.

Detailed explanation-2: -As the myosin S1 segment binds and releases actin, it forms what are called cross bridges, which extend from the thick myosin filaments to the thin actin filaments. The contraction of myosin’s S1 region is called the power stroke (Figure 3).

Detailed explanation-3: -Myosin filaments (also called thick filaments) are key components of muscle and non-muscle cells. In striated muscle, they overlap with thin (actin-containing) filaments in an orderly array, making a repeating pattern of sarcomeres, the basic units of contraction [1] (Figure 1a).

Detailed explanation-4: -Cross-bridges at various angles are seen between the thick and thin filaments binding in the actin target zones at 38.7-nm axial intervals on the thin filaments. Some cross-bridges are also seen binding in between the target zones.