Sliding Filament Theory

• How do the sarcomeres contract?


  Myosin and actin filaments slide over one another to make the sarcomeres contract - the myofilaments themselves do not contract
• What means that the myofibrils and muscle fibres contract?


  The simultaneous contraction of lots of sarcomeres means the myofibrils and muscle fibres contract
• What happens as the muscle relaxes?


  Sarcomeres return to their original length
• Contracted sarcomeres- describe?


  • A-bands stay the same length
  • I-band gets shorter
  • H-zones get shorter