6.3.1 Structure of Skeletal Muscle

• H zone = only myosin
• I band = only actin; light
• A band = both actin & myosin; darker
• Z line = start and end 
• Structure of myofibrils

  • Contractile muscle fibres; Made up of repeating units called sarcomeres
  • Individuals muscle fibre cells are called the sarcoplasm (shared cytoplasm & nuclei)
  • A lot of mitochondria
  • Sarcomeres up of two types of protein: myosin and actin
• • Myosin is thicker
• • Actin is thinner
• • Tropomyosin forms a fibrous strand around the actin filament