Sliding Filament Model
| Type | Responds to | Some Locations |
|---|
| 1. When a muscle is relaxed, myosin and actin filaments are not attached. | Actin Myosin | Relaxed myofibril Z line - Z line Sarcomere |
| 2. During contraction, myosin attaches to binding sites on actin, forming cross-bridges. Using ATP, the cross-bridges pull the actin toward the center of the sarcomere. | Binding sites→ Cross-bridge ATP | Contracting myofibril → ← |
| 3. The cross-bridges break, myosin binds to another site, and the cycle begins again until the muscle fiber is contracted. | → | Contracted myofibril |