Muscles & muscle contraction

• What are the three types of muscles in the human body?

  Smooth, Skeletal (Striated), Cardiac
• What is the definition of a muscle?

  A bundle of fibrous tissue in a human that contracts, producing movement or maintaining position
• What are the elements, functions, and locations of the three muscle types?

  • Skeletal: Long, Voluntary, Attached to bones
  • Cardiac: Short, Pumps blood, Heart
  • Smooth: Short, Involuntary, Walls of major organs
• What is the anatomy of skeletal muscle from muscle to myofibrils?

  1. Muscle
  2. Epimysium
  3. Fascicles
  4. Perimysium
  5. Muscle fibres (cells)
  6. Endomysium
  7. Myofibrils
  8. Thick & thin filaments (myofilaments)
• What are the two types of myofilaments in skeletal muscle?

  Myosin and Actin
• What are the zones of a sarcomere?

  • Z line
  • I band
  • A band
  • H zone
• What is the sliding filament theory of muscle contraction?

  It describes how myosin interlocks with actin to shorten the sarcomere
• What triggers the opening of calcium ion channels in muscle contraction?

  A nerve impulse traveling along a neuron to the muscle cell
• What happens when calcium ions diffuse into the sarcoplasm?

  Calcium ions bind to troponin, causing tropomyosin to move
• What is the role of ATP in muscle contraction?

  ATP binds to myosin head, causing it to detach from actin
• What happens to myosin heads during muscle contraction?

  They change shape and pull actin filaments along
• What is the result of myosin heads detaching from actin?

  Myosin heads attach to the next binding site along the actin filament
• What occurs when calcium ions are released during muscle contraction?

  The process of muscle contraction continues as long as calcium is present
• How does the sarcomere change during muscle contraction?

  The sarcomere shortens as actin filaments are pulled towards each other
• What are the steps involved in muscle contraction?

  1. Nerve impulse travels to muscle cell
  2. Calcium channels open, calcium ions diffuse in
  3. Calcium binds to troponin, moving tropomyosin
  4. Myosin binds to actin, forming cross-bridges
  5. Myosin heads pull actin, releasing ADP
  6. ATP binds to myosin, causing detachment
  7. Process repeats if calcium is present