Animation of energy release during muscle contraction involving the proteins myosin orange and actin green. Calcium ions purple bind to troponin T. This moves tropomyosin red out the way and allows the myosin head to bind flash to the actin myofilament. ADP adenosine diphosphate and Pi phosphate are attached to the myosin head, and when the binding occurs to form cross_bridges the Pi is released. Energy stored in the head of the myosin filament orange is used to move the head. This causes the actin myofilament green to slide past the myosin myofilament. The ADP is released from the myosin as it moves. The bond between the actin and myosin head is broken when an ATP adenosine triphosphate molecule binds to the myosin head. The ATP is broken down to ADP and Pi, releasing energy, which is stored in the myosin head and will be used later for movement. Master same as original.