3. Draw a relaxed and contracted sarcomere (see Textbook, p. 286, Fig, 11,6):

A sarcomere is the basic unit of muscle fiber. In the **relaxed state**, the thin filaments extend from the Z-disks towards the center, and the thick filaments are partially overlapping in the A-band. The I-band is wider, and the H-zone exists where only thick filaments are present. In the **contracted state**, the thin and thick filaments slide past each other, increasing the overlap. The I-band becomes narrower as the thin filaments are pulled inward, and the H-zone diminishes. Overall, the sarcomere shortens. **Relaxed Sarcomere:** ``` Z |----I----|====|----I----| Z ``` **Contracted Sarcomere:** ``` Z |==I==|====|==I==| Z ``` These diagrams show the structural differences between a relaxed and contracted sarcomere, highlighting how muscle contraction occurs through the sliding of filaments.