AN SC 310 - 13

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ebacker
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180909
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AN SC 310 - 13
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2012-10-31 00:34:20
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AN SC 310
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Lecture 13 - Muscle Physiology
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  1. Who were the 2 most influential scientists of muscle physiology?
    • Luigi Galvani
    • Alessandro Volta
  2. What are the 3 classifications of muscles?
    • Skeletal
    • Smooth
    • Cardiac
  3. What is a muscle?
    Group of fascicles
  4. What are muscles fixed to?
    • Bones
    • Tendons
  5. What is muscle membrane called?
    Sarcolemma
  6. What is muscle cell plasm called?
    Sarcoplasm
  7. What is the reticulum in muscle called and what is it similar to?
    • Sarcoplasmic reticulum
    • Smooth endoplasmic reticulum
  8. What gives muscles a striated appearance?
    Myofibrils: actin and myosin
  9. What is thick filament?
    Actin
  10. What is thin filament?
    Myosin
  11. What is the smallest functional unit of muscle?
    Sarcomeres
    • 1. A band
    • 2. I band
    • 3. H band
    • 4. Crossbridges
    • 5. Actin
    • 6. Myosin
    • 7. Z line
    • 8. M line
    • 9. Sarcomere
    • 10. Myofibril
    • 1. Sarcomere
    • 2. Z line
    • 3. M line
    • 4. H band
    • 5. A band
    • 6. I band
  12. What is a contractile protein?
    Actin
  13. What are 2 regulatory proteins?
    • Tropomyosin
    • Troponin
  14. What are the 3 types of troponin and what do they do?
    • A - Actin binding
    • T - Tropomyosin binding
    • C - Calcium binding
  15. What are the 2 binding sites on actin heads?
    • Actin-binding site
    • ATPase site
  16. What is the "bare zone"?
    Site on thick filament that has no crossbridges (heads)
  17. Which line/band are myosin head and tail near?
    • Tail - toward M line
    • Head - toward I band
  18. What provides elasticity in muscles?
    Titin
  19. What is the sliding-filament model?
    Thick and thin filaments do not shorten, they overlap and slide past e/o
  20. What bands shorten during contraction?
    • I band
    • H band
  21. What are crossbridge cycles?
    Cyclical formation of links btwn actin and myosin resulting in the sliding of thin filaments toward the M ling of a sarcomere
  22. Crossbridge cycle
    What is the power stroke?
    Myosin head pivots, pulling the actin filament with it
  23. Crossbridge Cycle
    What is rigor?
    Myosin and actin are tightly bound
  24. Crossbridge Cycle
    What is binding?
    Pi is realeased from the ATPase site
  25. Crossbridge Cycle
    What is cocking?
    ATP is hydrolyzed; myosin is in its high-energy form
  26. Crossbridge Cycle
    What is unbinding?
    The myosin head detaches from the actin
  27. What is asynchronous cycling and why does it occur?
    • Crossbridge cycles are purposely out of step with e/o
    • Muscle cells can continuously generate force during contraction
  28. What is excitation-contraction coupling?
    Sequence of events whereby an AP in the sarcolemma causes contraction
  29. What are the 2 most important factors in muscle contraction?
    • Neural input from motor neuron
    • Ca2+ release from sarcoplasmic reticulum
  30. What is the role of Ca2+ in contraction?
    Binds to troponin = movement of troponin = movement of tropomyosin = exposed binding sites for myosin on actin = crossbridge cycle = contraction
  31. What are the 6 steps of excitation-contraction coupling?
    • 1. AP in sarcolemma
    • 2. AP down T tubules
    • 3. DHP receptors of T tubules open Ca2+ channels in lateral sacs of SR
    • 4. Ca2+ increases cytosol
    • 5. Ca2+ binds to troponin, shifting tropomyosin
    • 6. Crossbridge cycling occurs
  32. What are the 2 receptors involved in Ca2+ release?
    • DHP
    • Ryanodine
  33. What must happen to terminate contraction?
    • Ca2+ must leave troponin
    • Tropomyosin covers myosin binding site on actin
  34. How is Ca2+ removed from cytosol?
    Ca2+ ATPase in SR transports it from cytosol into SR

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