Vet Histology lectures 6 &7

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Vet Histology lectures 6 &7
2013-09-17 08:07:36
Vet Histology lectures

Vet Histology lectures 6 &7
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  1. What are 2 striated muscle types
    Skeletal cardiac
  2. What is the only muscle type non striated?
  3. Which muscle type is voluntary
  4. What is a muscle fiber?
    A really huge multinucleated muscle cell
  5. What is a tissue?
    Aggregate of cells and intercellular substances specialized to perform a particular function
  6. While the size of a band changes during contraction and relaxtion does the actin and myosin length itself?
  7. What colour is the I band? A band?
    • I = light
    • A = dark
  8. What are 4 basic tissues?
    • Epithelium
    • Connective
    • Muscle
    • Nerves
  9. A cyte is a _____ cell? While a blast is a _____ cell?
    • Mature
    • Immature
  10. In skeletal muscle where do we find th enucleus almost always? Why?
    • On the edge of the fiber
    • Cause all th ebands push it there
  11. What is a satellite cell?
    sits in basement membrane essentially undifferentiated stem cell, can add nuclei to the muscle fibers and make it grow
  12. When you excersise do your muscles grow or do you get more of them?
    They grow
  13. Describe hypertrophy in muscle cells?
    Increase in size
  14. What is a  myofibril?
    Bundle of actin and myosin within a cell
  15. Differentiate between a myofibre and myofibril
    Fibre is cell fibril is within a cell
  16. Define endomysium, epimyisum, and perimysium
    • Endo = inbetween individual cells
    • Peri = inbetween bundles
    • Epi = on outside of muscle
  17. Are the bands in a muscle all lined up generally evenly? Like A to A and I to I?
    Yes usually to an extent
  18. Holes on surface of the sarcolemma leading to tubes used to conduct electricity are called?
    T tubules
  19. Why do T tubules make sense for skeletal muscle
    • Generally we want the entire muscle fibre to contract at once the myofibrils on the inside and outside so the T tubules allow penetration through the entire cell and allow the AP to stimulate everything
    • Generally in other kinds of muscle this perfect timing is not so important
  20. Plasma membrane in muscles is the ? What about smooth ER?
    • Sarcolemma
    • Sarcoplasmic reticulum
  21. What band disappears during contraction (or can)?
    H band
  22. What is a motor unit?
    A group of fibers to be contracted at once, 1 nerve  for tonnes of fibers
  23. What is the thin filament?
  24. What covers the binding sites on actin?
  25. What pulls the troponin complex off of the actin?
  26. The tail of myosin is made of what?
    2 heavy chais twisted around eachother
  27. is myosin directly anchored itself to the Z line? What about actin?
    • No only through titin
    • Yes
  28. A sarcomere is measured from?
    Z line to Z line
  29. Why do we see bands in the first place? What band is within the A band? What line is within that?
    • Cause different proteins make up different bands
    • H band
    • M line
  30. which fiber type (red/white) is faster? Uses mor Oxygen? has more mitochondria? is anaerobic primarily?
    • White
    • Red
    • Red
    • White
  31. What is the purpose of a muscle spindle?
    TO gauge the tension on the muscle
  32. Do skeletal muscles have gap junctions?
    Nope they are all one cell why would they need it
  33. In cardiac muscles what connects cells
    Intercallated discs
  34. Are cardiac muscle cells as long and connected as skeletal?
    No they are short and autonomous
  35. Are cardiac muscles controlle dby the brain at all?
    No they are purely autonomous
  36. How is myofilament shape in cardiac muscles? do we see striations and the same movement?
    Yes it is it the exact same and you get the same movement however the shape of the cell is not the same
  37. on a transverse cut through thecardiac muscle we happened to cut right through a nucleus and it appeard as a black dot surrounded by an empty space? What is the space for?
    Storage space for glycogen and lipids
  38. Where would we expect to see more mitochondria in cardiac muscle or smooth muscle?
    Cardiac muscle cause it runs contantly and is unyielding can see as much as 20-40% of cytoplasm as mitochondria
  39. Do we see the same level of SR in the cardiac muscle?
    No it is less developed which means that we don't rely on it as much and T tubule does more Ca release
  40. Name 4 differences between skeletal and cardiac muscle
    Cardiac is not one giant long multi nucleated cell, a lot more mitochondria, not as developed SR, autonomous
  41. Do we still the banding pattern in muscles when O 2 is lost?
    No and they contract in a funny way
  42. Myocardial infarction?
    Heart attack
  43. How many arteries does the heart have? How does gthis compare to other important organs? Describe the relevance to myocardial infarction
    • 1
    • low
    • If it gets plugged with plaque you die
  44. in the intercalated dsics of cardiac muscle cells what are some things we find? What do these look like?
    • desmosomes
    • gap junctions on the vertical part that done support any tension
    • Spot welds (des) and discs (gap junctions)
  45. describe how the muscle cells in the heart communicate and how this gives a very rhythmic contaction profile of it
    • They are not all connected and so there is a lag while they communicate vetween the gap junctions this means cell #2 contracts some time after Cell #1 after this lag occurs causing a drawn out squezzing effect
    • if all the muscles contracted at once in the atrial the blood would go no where
  46. Cardiac impulse conducting fibers are also known as?
    Purkinje fibers
  47. Purkinje fibers fire because of what?
    They are very leaky and so spontaneously fire at a base frequency
  48. Where do purkinje fibers originate?
    Nodes such as the AV or Sa node
  49. Histologically what do purkinje fibers look like?
    A lot larger in cross diameter than cardiac muscles
  50. How does the action potential spread through cardiac muscle?
    • Through the gap junctions to the next cell
    • This causes orderly and sequential contraction
  51. Do cardiac muscles have satellite cells?
    Essentially no
  52. Can the heart beat without the brain?
    Yes it is autanomous
  53. What determines the strength of a contraction in skeletal muscle as compared to cardiac muscle?
    • Skeletal muscle it is the number of fibers contracting but all fibers go full force
    • In cardiac muscle it is the extent the cells contract but they all contract
  54. Is the cardiac muscle able to divide at animal maturation?
    No the ability to divide is lost after birth
  55. How does the heart grow?
    Heart grows cause cells and individual fibres grow
  56. Damage to the heart wall (infarction leads to death of myocytes. What usually fills this gap?
    Connective tissue proliferation
  57. How does smooth muscle appear? Does it have any striations? Why does it appear smooth?
    • Smooth and silky
    • No
    • Cause actin and myosin are not in any definitive arrangement like in the other muscles and therefore don't make a pattern
  58. Which muscle type is the most efficient and has the highest amount of contracting power
  59. Smooth muscle
  60. What is the shape of a smooth muscle cell and what is the shape of the nucleus
    Cigar shaped nucleus and a spindle shaped cell
  61. What interconnects muscle fibers?
  62. In the intestines how many layers of muscle are there?
  63. Do all visceral orgajns have smooth muscle?
    Yes to an extent
  64. Does each smooth muscle need its own nerve?
    No one nerve kind of dumps out and many muscle cells pick it up
  65. Do Smooth muscles have T tubules?
    No they lack that entire system  they have vesicles that take in Ca and the contraction mechanism is completely different
  66. What are dense bodies?
    They are places where both actin and intermediate filamnents in smooth muscle attach to both in the cytosol and on the plasmalemma it is there anchor per say
  67. What is a third type of filament smooth muscle cells have?
    Intermediate filaments made of desmin
  68. Smooth muscle is a very efficient contractor, describe what we see in a smooth muscles appearanbce when it contracts
    It contracts so much that is essentially bundles up and kinks
  69. What do we call a neuromuscular synapse in a muscle?
    A motor end plate
  70. What is the difference in muscle spindles in smooth muscle?
    They are very prominent so w e often study them here
  71. Describe what is inside a muscle spindle?
    • Modified skeletal muscles much smaller with a capsule surrounding it
    • Sensory nerves within it detect how much muscle is being contracted and makes the brain think about the tension
    • Surrounded by modified perimysium
    • Has proprioreceptors for nerves to detect tension
    • Small muscle fibers are called intrafusal fibers
  72. Do skeletal muscles have gap junctions?
    Yes this is how they communicate
  73. Do skeletal muscles have gap junctions
    NO don't need em to communicate
  74. What are purkinje fibers modified from?
    Cardiac muscle