2. Which band is the light band? 3. In which band do the actin and myosin overlap? 4. The myosin extends the length of the band. 5. The z lines are located in the middle of the bands. 6. The boundaries of a sarcomere are the 7. Which two regions of the sarcomere shorten when a muscle contracts? and 8. Which region of the sarcomere does not shorten when a muscle fiber contracts? 9. The H zone is located in the middle of the band. 10. The structural and functional unit of a muscle fiber is the