Sliding Filament Model

• Sliding Filament Model

  • Explains how muscle contraction works.
  • When muscles contract, the sarcomeres shorten.
  • This occurs because the actin and myosin filaments slide over one another.
• 1. A sarcomere runs from Z line to Z line
• 2. For contraction of muscle to occur, ATP (energy) is required
• 3. Calcium is released from sarcoplasmic reticulum
• 4. This calcium will diffuse onto the myofibril and attach to the troponin molecules which are located on the actin myofilaments.
• • 5. Actin is found inside the sarcomere which is attached to the Z lines (anchor points) and...
  • Is a thin filament
  • Actin is only located in the A Band
• 6. Myosin is thick filament

  • Myosin is also located in the A Band
• 7. For a muscle to shorten, the myosin filament head/cross bridge will attach to the actin filament and the myosin filaments will pull on the actin filaments
• 8. The actin filaments slide over the myosin filaments
• 9. The filaments do not change in length
• 10. Z lines become closer together/shortens
• 11. This caused the sarcomere to shorten
• 12. The I band/region where only actin occurs, shortens
• Sliding Filament Model Diagram