Topic 6: Muscular System Part 1

• What is the scientific study of muscles called?

  Myology
• What are the types of muscular tissue and their characteristics?

  • Skeletal: Striated, voluntary, attached to bones
  • Cardiac: Striated, involuntary, wall of heart
  • Smooth: Non-striated, involuntary, viscera
• What are the five key functions of muscular tissue?

  1. Producing body movements
  2. Stabilizing body positions
  3. Regulating organ volume
  4. Moving substances within the body
  5. Releasing heat
• What covers an entire muscle?

  Epimysium
• What covers muscle fascicles?

  Perimysium
• What covers individual muscle fibres?

  Endomysium
• What are tendons?

  Extensions of connective tissue attaching muscle to bone
• How are skeletal muscles supplied?

  Well supplied with nerves and blood vessels
• What are muscle fasciculi?

  Groups of skeletal muscle fibres
• What is a skeletal muscle fibre?

  A multinucleated cell acting as a contractile unit
• What is the plasma membrane of a skeletal muscle fibre called?

  Sarcolemma
• What do transverse tubules (T-tubules) do?

  Tunnel from surface toward muscle fibre center
• What is the functional unit of striated muscle fibres?

  Sarcomere
• What are the thick and thin filaments in muscle fibres?

  Thick: Myosin; Thin: Actin, tropomyosin, troponin
• What is the role of the sarcoplasmic reticulum?

  To store calcium ions for muscle contraction
• What happens when calcium ions are released from the sarcoplasmic reticulum?

  They bind to troponin, exposing myosin-binding sites
• What are the phases of a muscle twitch?

  1. Latent period: Action potential propagation
  2. Contraction phase: Tension increases, cross-bridges form
  3. Relaxation phase: Tension decreases, Ca++ ions pumped out
• What is muscle tension?

  The force generated by a contracting muscle
• What are the two main types of skeletal muscle contractions?

  • Isotonic contractions: Tension stays constant
  • Isometric contractions: Tension without length change
• What is muscle fatigue?

  The inability to contract forcefully after prolonged activity
• What is recovery oxygen uptake?

  Elevated oxygen use after exercise
• What are the sources of ATP production in skeletal muscle fibres?

  1. Creatine phosphate
  2. Anaerobic glycolysis
  3. Aerobic respiration
• How long can creatine phosphate and ATP provide energy for muscle contraction?

  About 15 seconds
• How long can anaerobic glycolysis provide ATP for muscle activity?

  About 2 minutes
• What does aerobic respiration yield from each glucose molecule?

  About 32-38 molecules of ATP
• What is the sliding-filament mechanism of muscle contraction?

  • Sliding of filaments
  • Shortening of sarcomeres
  • Requires Ca2+ and ATP
• What is the contraction cycle in muscle contraction?

  1. Splitting ATP
  2. Forming cross-bridges
  3. Power stroke
  4. Binding ATP & detaching
• How does muscle tension change when muscles are stretched beyond resting length?

  Muscles produce less tension
• What is the ideal length of a sarcomere for maximal tension?

  When thick and thin filaments optimally overlap
• What are the effects of exercise on skeletal muscle tissue?

  • Increases muscle strength
  • Enhances endurance
  • Promotes muscle hypertrophy