LS2:Musculoskeletal Systems

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LS2:Musculoskeletal Systems
2012-06-13 05:38:15

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  1. 3 types of vertebrate muscle
    • 1.Skeletal:voluntary movement
    • 2.Cardiac:beating of the heart
    • 3.Smooth:Involuntary, movement of internal organs
  2. Skeletal muscle cells are...
    • 1.Muscle fibers
    • -large and multinucleate
  3. Skeletal muscles form from....
    fusion of embryonic myoblasts
  4. Epimysium
    wrap around muscle
  5. fasicicles
    inside muscle
  6. Perimysium
    wraps around Fasicles
  7. Endomysium
    wraps the muscle fibers
  8. How does Muscle get activated?
    • 1.Brain sends signals to muscles fiber
    • 2.Axon of neuron binds to skeletal muscle fibers
  9. Fine motor control
    one axon to one muscle fiber
  10. gross motor control
    one axon to many muscle fibers
  11. Actin
    thin filaments
  12. Myosin
    thick filaments
  13. Myofibrils
    Bundles of actin and myosin filament
  14. How actin filaments surround one myosin filament?
  15. Sarcomeres
    1. Repeating units of overlapping actin and myosin filaments
  16. each sarcomere is bounded by...
    Z lines
  17. what anchors actin?
    Z lines
  18. A band
    • 1.Center
    • 2.Contains myosin and no actin
  19. I band
    1.Actin, yet no myosin are present
  20. H zone
    • where actin and myosin do not overlap
    • -myosin but no actin
  21. Titin
    the largest protein in the body
  22. M band
    holds the myosin together
  23. What is muscle contraction initiated by?
    1.Initiated by action potentials from motor neuron at neuromuscular junction
  24. Myosin structure
    • 1.Two polypeptide chains coiled together
    • 2.Globular head
  25. Actin structure
    • Long twisted molecule
    • -tropomyosin twists around it
  26. Motor unit
    all the muscle fibers activated by one motor neuron
  27. To increase strength of muscle contraction....
    • 1.Increase rate of firing of motor neuron
    • 2.Recruit more motor neurons to fire
  28. what blocks the binding sites on actin?
    at rest, tropomyosin blocks the binding sites on actin
  29. Steps of muscle contraction
    • 1.Neuron action potential arrives at end of motor neuron
    • 2. ACH is released
    • 3. ACh binds to receptors on motor end plate
    • 4.Permeability of sarcolemma changes (Na rushes in)(an action potential is produced)
    • 5.Muscle action potential sweeps into the T tubules
    • 6. triggering release of Ca from the sarcoplasmic reticulum
    • 7.CA binds to troponin
    • 8.Troponin changes shape and shifts tropomyosin to expose binding sites of actin
    • 9. myosin binds to actin (ADP released from myosin)
    • 10. Myosin head pivots (pulling actin)
    • 11. Myosin releases from actin
    • 12. Myosin re-extends (ATP---ADP)
  30. what cells initiate and coordinate heart contractions>
    Pacemaker and conducting cells
  31. Myogenic
    Heartbeat is myogenic, generated by the heart muscle itself
  32. Smooth muscles have electrical contact by...
    gap junctions
  33. Smooth muscle contraction
    • 1.Ca2+ influx tp sarcoplasm, stimulated by stretching
    • 2.Ca2+ binds with calmodulin
    • 3.Activates myosin kinases, which phosphorylates myosin heads
    • 4.Bind and release actin
  34. Twitch
    minimum unit of contraction
  35. Tension generated by entire muscle depends on:
    • • Number of motor units activated
    • • Frequency at which motor units are firing
  36. Tetanus
    action potentials arrive so rapidly that the sarcoplasmic reticulum does not have time to reclaim the calcium ions.
  37. How long muscle fiber can sustain tetanic contraction depends on
    ATP supply
  38. To maintain contraction, actin-myosin bonds have to keep....
  39. ATP is needed to break the
    actin-myosin bonds, and“re-cock” the myosin heads
  40. Slow-twitch fibers
    • 1.Oxidative or red muslce
    • 2.Contain myoglobin:oxygen binding protein
  41. Slow-twitch fibers
    • 1.Have reserves of glycogen and fat
    • 2.Can produce ATP if oxygen is available
  42. muscles with high proportions of ______ are good for aerobic workout (e.g., long distance running, cycling, swimming, etc.).
    slow-twitch fibers
  43. Fast-twitch fibers
    • 1.Glycolytic or white muscle
    • 2.Fewer mitochondria, few blood vessels
    • 3. Good for sprints, fatigue quickly
    • 4.Largely genetic
  44. Muscles have three systems for supplying ATP for contractions:
    • 1.immediate system: uses preformed ATP and creatine phosphate
    • 2.Glycolytic system: metabolizes carbohydrates to lactic acid and pyruvate
    • 3.Oxidative system: metabolizes carbohydrates or fats to H2O and CO2