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2011-03-15 09:07:34
Human Physio

Chapter 19
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  1. what are the layers of connective tissue?
    epimysium, perimysium, endomysium
  2. what are the 4 functions of connective tissue?
    • 1. perimysium provides a conduit for blood vessels and nerves
    • 2. resist passive stretching
    • 3. distribution of contractile forces
    • 4. elasticity enables the muscle belly to regain shape when forces are removed
  3. where is most of the calcium stored?
    terminal cisternae
  4. satellite cells are responsible for what?
    replacing damaged fiber/muscle
  5. what are myotubes?
    immature muscle fibers
  6. what is proliferation?
    satellite cells are activated resulting in the formation of myoblasts
  7. what is differentiation?
    myoblasts fuse together to form a multi-nucleated cell type called a myotube
  8. what is maturation?
    myotubes grow to form myofiber
  9. what are the stages of myogenesis?
    satellite cells - proliferation - myoblasts - differentiation - myotubes - maturation - myofibers
  10. name 3 cytoskeletal proteins
    contractile (actin and myosin), regulatory (troponin and tropomyosin) and structural
  11. where are troponin and tropomyosin found?
    actin (thin filament)
  12. what are the 4 functions of exosarcomeric proteins?
    • 1. link sarcomeres to the sarcolemma
    • 2. transmission of contractile force to the sarcolemma
    • 3. spatial arrangement of the myofibrils
    • 4. anchor for organelles
  13. what is dystrophin?
    cytoseletal filaments that cross together combined with actin and spectrin
  14. what is the function of endosarcomeric proteins?
    • 1. transmission of contractile forces to the Z lines
    • 2. spatial arrangement of the actin and myosin filaments
  15. what are considered endosarcomeric proteins?
    nebulin (helps align actin), titin (provides elasticity and stability to myosin expanding from one Z disk to the M line)
  16. explain the steps to a power stroke
    • 1. myosin head engergized before attaching to actin
    • 2. cross bridge to actin
    • 3. releasing of Pi causes change in myosin
    • 4. power stroke causes fliaments to slide, ADP is released
    • 5. new binding of ATP to myosin allows the release of actin
    • 6. ATP is hydrolyzed causing cross bridge to return to its original orientation
  17. what provides the energy for cross bridge formation?
    hydrolysis of ATP
  18. what does calcium do for the myosin?
    exposes the binding site by binding to the troponin complex
  19. 2 types of ion channels and what they respond to
    • 1. voltage - membrane potentials
    • 2. chemically - neurotransmitters
  20. where are voltage ion channels found?
    axon of motor neurons and sarcolemma
  21. where are chemically regualted ion chennels found?
    dendrite and motor end plate
  22. what is the axon hillock?
    region of a neuron capable of generating an action potential
  23. how does the action potential travel?
    always from axon hillock to axon terminal
  24. what is a refractory period?
    degree of readiness of an axon to generate an action potential
  25. what is absolute refractory period?
    portion is incapable of generating an action potential
  26. what is relative refractory period?
    portion is capable of generating an action potential provided that the stimulus is strong enough
  27. what part of the motor neuron is exposed to extracellular fluid?
    the axon at the node of ranvier
  28. what are the components of the neuromuscular junction?
    axon terminal, synaptic cleft, motor end plate
  29. what happens to ACH at a NMJ?
    released from axon terminal, binds to receptor on motor end plate resulting in entry of Na, then degraded by acetylcnolinesterase which is found on the endomyosium
  30. T-tubules contain what receptor?
    dihydropyridine (DHP)
  31. what is the channel called that is connected from the T-tubule to the SR?
    ryanodine channel
  32. when Ca is released from the ryanodine channel, what happens?
    power stroke
  33. type 1 muscle fiber
    slow twitch
  34. type 2a muscle fiber
    fast twitch (anaerobic/aerobic)
  35. type 2b muscle fiber
    fast twitch (anaerobic)
  36. small motor unit innervates what muscle fiber?
    type 1
  37. fast fatigue resistant innervates what muscle fiber?
    type 2a
  38. fast fatigable innervates what muscle fiber?
    type 2b
  39. what muscle type has a high glycogen content?
    type 2b
  40. why are there differences in twitch contraction times?
    motor neuron conduction velocity, myosin ATPase activity
  41. which muscle fiber generates the fastest twitch tension? why?
    type 1 - smaller motor units
  42. what are the anaerobic capacity differences in the fatigue index?
    creatine phosphate and glycolytic enzymes activity
  43. what are the aerobic capacity differences in the fatigue index?
    oxidative enzymes, myoglobin content, number of mitochondria, capillaries