The trick to a muscle cell’s contraction is that these two fibers—actin and myosin—slide against each other, like two networks of ropes. When a cell is stimulated to contract, a part of the myosin fiber binds to a site on the actin fiber, like a hand from one rope gasping the other. It then unclutches it and reaches forward to bind to the next site—a man suspended on one rope, grasping and pulling on the other, one fist upon the next. Clutch. Pull. Release. Clutch. Pull. Release.
