ABSTRACT
In Section 2.3, the basic structure of a muscle ber and its composition are described (see Figure 2.5). Muscle contraction occurs by a sliding lament mechanism whereby the sarcomeres as the structural units of the myo- brils shorten (the Z-lines come together, close to each other) by the action of the actin filaments sliding over the myosin filaments. A myosin lament head is large and looks like a golf ball. e force behind a muscle contraction is the ratchet movement of the myosin heads toward the center of their sarcomere. In fact, the ratchet movement is the muscle contraction itself (Figure 5.1).
