Vet histology readings pg 191-211

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Vet histology readings pg 191-211
2013-09-14 17:17:57
Vet histology readings pg 191 211

Vet histology readings pg 191-211
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  1. What are generally considered the 3 types of muscle
    • Smooth
    • Skeletal
    • Cardiac
  2. Describe skeletal muscles
    • Very long multinucleated cylindrically shaped with striations upon them
    • Has a sarcolemma surrounding them
  3. What is a group of muscle fibers called? What is it surrounded by?
    • Fascicle
    • Perimysium
  4. WHat makes up the inside of a muscle fiber?What would the contractile units of thes ebe called?
    • myofibrils composed of thick myosin and thin actin filaments
    • Sarcomere
  5. Are thick and thin filaments attached directly?
    No they interdigitate betweek eachother
  6. Which filament has a globular head? Where does it point too? Which proteins is it associated with mostly?
    • Myosin has the globular head
    • towards f actin
    • tropomyosin
    • troponin
  7. What seperates sarcomeres?
    Z discs or lines
  8. Which part of the Z disc do the thin filaments attach to
    The alpha actinin
  9. Light bands are called? Dark bands are called?
    • I bands
    • A bands
  10. What is the sarcoplasm?
    Cytoplasm of muscle fibre
  11. What is the sarcoplasmic reticulum? What does it do?
    • Mitochondria and cisternae of smooth ER
    • Calcium sequestration and release
  12. At each sarcomere What will we find (Hint: has to do with Sarcoplasmic reticulum) What do they come in contact with? What is the purpose of this?
    • Terminal cisterns of SR
    • a deep invagination of sarcolemma called the T tubule
    • Forms a triad that triggers Ca2+ release when the sarcolemma is depolarized
  13. What has to happen to allow the myosin head to bind to the actin subunit? This forms what?
    • calcium binding to the troponin causes tropomyosin to change shape.
    • Cross bridges between thick and thin filaments
  14. Once myosin heads are bound to actin how does contraction actually happen
    ATP hydrolysis pivots the head sliding the two filaments along eachother
  15. With both Ca and ATP present for the contraction what do we see occur?
    A contraction cycle ensures where myosin heads repeatedly attach pivot detach and return causing shortenting of the sarcomere
  16. When membrane depolarization ends describe what happens?
    Ca is sequestered thus binding of tropomyosin ends thus covering the actin binding sites and stopping contraction allowing muscles to relax
  17. What do you call the synapse of a motor neuron and a skeletal muscle? (3 names)
    • Motor end plates
    • Neuromuscular junctions
    • Myoneural junctions
  18. What is the primary neurotransmitter between neurons and skeletal muscle
  19. Do motor axons only innervate one muscle fiber? What do you call the unit?
    • No often they will end with many motro end plates on many different muscle fibers
    • All the fibers a nerve innervates is call the motor unit
  20. Differentiate between muscle spindles and tendon organs? What is the same about them?
    • They are both used to detect tension on the muscle
    • The difference is muscle spindles are miny muscle bundles that attach to sensory proprioceptors while the tendon organs are nerves that attach to tendons to test the same thing
  21. Where do tendon organs penetrate?
    Into the collagen bundles at the myotendionous junction
  22. So in muscle spindles the proprioceptors wrap around what? What about in tendon organs?
    • Intrafusal fibers
    • Myotendinous collagen bundles
  23. Describe the three types of skeletal muscle fibers?
    • Type 1: Slow oxidative
    • Type 2 (a): Fast intermediate oxidative-glycolytic
    • Type 3 (2b) : Fast glycolytic
  24. Are cardiac muscles smooth?
    No still striated
  25. Describe the difference in cell size between cardiac and skeletal muscle
    Cardiac is not all one big muscle, it is long normal muscle cells with normally 1 nucleus
  26. How do cardiac muscle cells attach
    Via intercalated discs
  27. Does the sarcomere differ in the cardiac muscle from the skeletal muscle
  28. Does the brain have input into the cardiac muscle?
    No its control is intrinsic at nodes of impulse generating pacemaker fibers
  29. Describe the shape of a smooth muscle cell?
    Tapering as compared to cigar shaped, so tweedles off into a twindle
  30. How are smooth muscle linked?
    Via numerous gap junctions
  31. Are there striations in smooth muscle? How does the sarcomere differ?
    • No
    • There isn't one
  32. What does actin attach to if there is no sarcomere in the smooth muscles?
    Dense bodies spread out around cell in sarcoplasm and sarclemma
  33. Do smooth muscle cells contract together or individually?
    Individually then they tell the next too, so it makes a sort of Squeezing motion
  34. What differs about the T tubule system in the smooth muscle?
    It doesn't exist
  35. There is a lack of troponin in smooth muscles So what protein controls the sliding of filaments?
    Myosin light-chain kinase (MLCK) as well as calmodulin
  36. Why don't smooth muscle cells need t tubules?
    Cause they contract individually and don't need that adaptation
  37. What does troponin do?
    Blocks binding site for myosin head
  38. Why can skeletal muscle repair and regenerate?
    • Because of the reserve satellite cells hanging out on it
    • They can proliferate and fuse to form new muscle fibers
  39. Can cardiac cell regenerate? Why?
    • No
    • No satellite cells
  40. Can smooth muscle cells regenerate? Why?
    • Yes!
    • Cause each one is relatively small and relatively less differentiated which can allow for renewed mitotic division
  41. Cardiac muscle cells are bound together by whatÉ
    Intercalated discs
  42. What is the sarcoplasmic reticulum analogous to in a normal cell?
    Smooth ER
  43. What is the sarcoplasm in a normal cell?
  44. What is a sarcolemma in a normal cell?
    Cell membrane
  45. What type of muscle do we see satellite cells in?
    Skeletal muscle
  46. Differentiate between epi, endo and perimysium
    • Epi = external
    • Peri = inbetween fascicle
    • Endo = between muscle cells
  47. What is a bundle of muscle cells called (the unit surrounded by perimysium)
  48. What is the junction of the tapering skeletal muscle and the continuing tendon?
    Myotendinous junction
  49. an A band is?
    Dark band where myosin is seen
  50. The I band is?
    Light band where only actin and titin is
  51. Differentiate between F action and G actin
    • F is the long chain of actin globules
    • G is the individual globule
    • G = globule
  52. Myosin is a complex containing how many of each chain?
    2 heavy chains making up tail and 4 light chains (2 pairs) making up heads
  53. Differentiate between tropomyosin and troponin
    • Tropomyosin is the long polypeptide coild sitting in the actin groove to stop myosin binding
    • Troponin is the complex of three subunits controlling the tropomyosin
  54. What makes up the Troponin complex
    • TnT = attaches to tropomyosin
    • TnC = binds Ca
    • TnI = Regulates actin myosin interactions
  55. What does titin do?
    Connects the myosin to the Z disc
  56. What Is nebulin
    • Large accessory protein
    • ┬ábinds each thin myofilament laterally
  57. What is myomesin
    part of the M line that holds thick filaments in place
  58. What are two proteins on the M line
    Myomesin and creatine kinase
  59. What is the purpose of creatine kinase on the M line?
    catalyzes transfer of phosphate groups from phosphocreatine (Phoasphate storage molecule) to ADP to supply the muscle with ATP
  60. When the myosin binds actin it forms a crossbridge and causes what else?
    actomyosin ATPase activity (catalyzing energy release)
  61. What is triad?
    two terminal cisterns of the sarcoplasmic reticulum on either side fo the T tubule
  62. What is a terminal cistern
    expanded cisterns of the SR on the side of a T tubule
  63. How does rigor mortis occur?
    In the absence of ATP after deatht he myosin and actin crossbridges become stable and the muscle is stuck in contraction
  64. What causes the release of the myosin head from the actin binding site so that it can make another pivot?
    ATP breaking down to ADP and P
  65. What removes acetylcholine from the synaptic cleft?
  66. The sarcolemma at the neuromuscular junction is in what shape? Why?
    • Junctional folds
    • Increase SA so to transmit impulses better
  67. What is an intrafusal fiber
    • thin muscle fibers found surrounding a muscle spindle along with flattened cells
    • (essentially modified perimysium)
  68. Where would we find myoglobin most likely?
    In muscles that have slow extended contractions cause they tend to do more oxidatitive phosphorylation and myoglobin has iron and stores lots of oxygen easily
  69. What two things make up intercalated discs? Why does this make sense?
    • Desmosomes and fascia adherents
    • Cause if joining muscle together has to be all about strength
  70. What structure allows cardiac cells to have ionic contiuity and essentially communicate contraction signals between eachother
    Gap junctions
  71. Another name for smooth muscle?
    Visceral muscle
  72. What are calveolae
    short membrane invaginations of smooth muscle
  73. in smooth muscle what replaces troponin?
    Calmodulin and Ca sensitive myosin light-chain kinase
  74. does cardiac muscle contract individually?
    Does it have T tubules?
    • Yes
    • No