Skeletal muscle

• What are the three types of muscle?

  Skeletal, cardiac, smooth
• What are muscles made up of?

  Myofibrils
• What gives myofibrils strength?

  Arranged parallel

  Fused together to form muscle fibres which share a sarcoplasm
• What is a sarcoplasm?

  A nucleus and a cytoplasm
• What are the two types of filament that make up a myofibril?

  Actin and myosin
• What is the structure of actin?

  Thinner, two strands twister around each other
• What is the structure of myosin?

  Thicker and consists of rod-shaped tails that project to the side
• What are the bands of the myofibrils?

  I band

  A band

  H zone

  Z line
• What are I bands?

  Actin and myosin do not overlap

  ’I am a thin filament’
• What are the A bands?

  Actin and myosin

  ’All the filaments’
• What is the H zone?

  The center of the A band of the sarcomere, where only myosin is present

  ‘Help I’m stuck in the middle of the sarcomere’
• What is a Z line?

  The boundary between sarcomeres

  ’Z-ee end of the sarcomere’
• What is another important protein involved with muscles?

  Tropomyosin, forms a fibrous strand around the actin filament
• What are slow-twitch fibres?

  Contract slowly and less powerfully over a long period of time

  Used for endurance work eg marathon running
• What are fast-twitch fibres?

  Contract rapidly for a short period of time

  Used for intense exercise eg weight lifting