First lets see if you remember what some of the structures are before we move on.
1. A cylindrical organelle running the length of the muscle fibre, containing Actin and Myosin filaments. Myofibril Actin Sarcomere Myosin
2. The functional unit of the Myofibril, divided into I, A and H bands. Myofibril Actin Sarcomere Myosin
3. A thin, contractile protein filament, containing 'active' or 'binding' sites. Myofibril Actin Sarcomere Myosin
4. A thick, contractile protein filament, with protusions known as Myosin Heads. Myofibril Actin Sarcomere Myosin
5. An actin-binding protein which regulates muscle contraction. Tropomyosin Actin Sarcomere Myosin
