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2011-03-16 12:39:16

HSP exam 2 muscles 1&2 study guides
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  1. Define a muscle fiber
    A muscle cell
  2. Define Sarcolemma
    a muscle cell's cell membrane
  3. Define sarcoplasm
    A muscle cell's cytoplasm
  4. Define fascicle
    A bundle of muscle fibers
  5. Define myofibrils
    Contractile/elastic protein bundles
  6. Define sarcoplasmic reticulum
    A modified endoplasmic reticulum found in muscle cells
  7. Define a motor unit
    A motor neuron and all the muscle fibers it innervates
  8. List the components of the muscle fiber
    • Sarcolemma
    • SR
    • T-tubules
    • Terminal cristernae
  9. What is the function on each component of the muscle fiber?
    • Scarcolemma-plasma membrane
    • SR-voltage modified ER
    • T-tubules-lumen is in contact with ECF
    • Terminal cristernae-direct Ca2+ release and allow AP form neuromuscular junction
  10. Describe the composition of Myosin
    Two chains wrapped around each other with a myosin head(crossbridge) which contains an actin binding site, ATP binding site, and ATPase
  11. Describe the composition of Actin
    Regulatory proteins troponin and tropomyosin
  12. What is the function of Titin?
    huge and connect the thick filaments in elastic way
  13. What is the function of Nebulin?
    Elastic giant molecule attaches to Z-disk and helps stabilize the thin filaments
  14. Describe the sliding filament theory of contraction
    The thin filaments slide of the thick filaments causing the sarcomere to shorten
  15. What happens to the lengths of the various bands and zones during contraction?
    • I-band: shortens
    • Z-disk: shortens
    • H-zone: shortens
    • M-line: remains the same
  16. Describe the basis of contraction
    • 1. Binding of myosin to actin
    • 2. Power strokes
    • 3. Rigor(low energy form)
    • 4. Unbinding of myosin/actin
    • 5. Cocking of myosin head (high energy form)
  17. Describe the regulation of contraction by tropomyosin and troponin
    tropomyosin lies on the top of the active binding site-then AP depolarizes the T-tubules and the SR releases Ca2+-Ca2+ binds to troponin-tropomyosin is pulled off the active site-myosin crossbridge binds to actin
  18. Describe skeletal muscle relaxation
    Cytosolic Ca2+ binds to SR Ca2+ channels--the channels close--Ca2+ is actively pumped back into SR by ATPase--cytosolic Ca2+ drops--Ca2+ unbinds from troponin--tropomyosin slides back over to cover the binding site--then the fiber relaxs
  19. List the sources of muscular ATP
    creatine phospate + ADP-----creatine +ATP
  20. Explain how exercise intensity affects muscle metabolism
    First it uses stored (very little) glycogen to make glucose. Then glucose and fatty acids are delivered through the blood stream. After approx. 30 min. the main energy sources is fatty acids.
  21. Describe how tension is generated in a single muscle fiber
  22. Describe Summation
    increased muscle tension
  23. Describe unfused tetanus
    stimuli are apart so this allows the muscle to relax in between segments
  24. Describe fused tetanus
    muscle reaches steady tension---this causes fatigue quickly
  25. Define isometric contraction
    muscle develops tension but doesn't change length----- standing
  26. Define isotonic contraction
    muscle shortens while the load remains constant-----picking up groceries
  27. Explain how fiber diameter affects force
    The greater the diameter of a fiber the more actin and myosin it has. the more actin/myosin in a cell, the more crossbridges that can be formed so the more force that fiber exerts
  28. Describe fast twitch glycolytic fibers
    Largest motor unit, least used, running/jumping
  29. Describe slow twitch oxidative fibers
    smallest motor unit, most used, posture
  30. Describe fast twitch oxidative fibers
    intermediate motor unit, standing/ walking
  31. List the possible causes of fatigue
    • psychological effects
    • protective effects
    • lowered neurotransmitter effects (Ach)
    • lowered receptor activation
    • change in muscle membrane potential
    • lowered Ca2+ release
    • lowered Ca2+ troponin reaction
    • depletion/accumulation theories
  32. Describe the composition of smooth muscle cells
    • not striated--parallel
    • coupled by gap junctions
    • behaves as a single unit
  33. Describe smooth muscle contraction
    Cell is depolarized--Ca2+ enters the cell from ECF--released from the SR--Ca2+ binds to protein calmodium--activates myosin kinase--phosphorylates light chains and myosin ATPase activity--activates myosin crossbridges--increase muscle tension
  34. Describe smooth muscle relaxation
    Ca2+ is pumped out of the cell into SR--Ca2+ unbinds from calmodium--myosin phosphatase removes phosphate--decreases ATPase activity--decreases muscle tension