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efrain12
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242260
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2.12
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2013-10-22 21:41:46
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physiology of contraction
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  1. what is a motor unit?
    a single motor neuron and all of the musce fibers it supplies
  2. what is nerve?
    bundle of neurons or bundle of nerve cells
  3. what is neuron?
    single nerve cell
  4. what is a muscle twitch?
    is motor unit's response to a single to a single AP of its motor neuron
  5. what are the 3 pahses in muscle twitch?
    -latency

    -contraction

    -relaxation
  6. phases of muscle twitch) Latency
    • -period between the stimulus and initiation of the muscle twitch response
    • *myogram shows no response
  7. phases of muscle twitch) Contraction (3)
    -we have cross bridge connection

    -onset of shortening of muscle

    -reaches from onset to the peak of power
  8. phases of muscle twitch) relaxation (2)
    -calcium reenters the sarcoplasmic reticulum

    -cross bridges let go
  9. Is twitch duration the same with all types of muscles?
    no, they differ by muscle fiber type
  10. which type of muscles have a faster twitch?
    muscles necessary for rapid response
  11. which type of muscle is an exmaple of slow twtich muscles?
    postural
  12. (increased muscle tension through graded muscle response) Summation- what is temporal?
    increases the rate of stimulus delivery
  13. (increased muscle tension through graded muscle response) summation- tetany?
    • no relaxation
    • *happens infreq.
  14. (increased muscle tension through graded muscle response) what is multiple motor unit summation?
    • sequentially more motor units are recruited as stimulus intensity increases
    • *smalled motor units are recruited first followed by larger ones
    • **end result is smooth, steady increase in force generated
  15. (increased muscle tension through graded muscle response) what is treppe?
    warm up effect
  16. (increased muscle tension through graded muscle response) why is treppe important?
    as muscle warms up, enzymes become more efficient and stronger contractions occur
  17. (increased muscle tension through graded muscle response) how does treppe differ from temporal summation?
    treppe has complete relaxation periods
  18. types of contraction) what is a contraction?
    force generated by cross bridges formation
  19. types of contraction) what is the force on object?
    tension
  20. types of contraction) what is the weight of object?
    load
  21. types of contraction) what is isotonic contraction?>
    -same tension

    -changing length
  22. types of contraction) 2 types of isotonic?
    -concentric

    -eccentric
  23. types of contraction) types of isotonic- concentric
    • shortens
    • *only type explained by Huxleys theory
  24. types of contraction)types of isotonic- Eccentric
    lengthen

    • ***occurs when we have a heavy object we lifted and then want to st it on a table carefully
    • *** short to long
    • ***not backed by huxleys
  25. types of contraction) isometric contraction? (2)
    -same length

    -changing force
  26. types of contraction) example of isometric
    • get out of chair and push against wall of house
    • *all of the muscles being used will not shorten or lengthen
  27. types of contraction) isokinetic
    • -same speed with controlled angular velocity of joint
    • **ex) these happen in exercise machines
  28. types of contraction) which two contractions are used in everyday lives?
    isometric and isotonic
  29. force of contraction) number of fibers and stimuli
    temporal summation and recreuitment of fibers
  30. force of contraction) size of muscle
    larger the muscle the larger the force
  31. force of contraction) having elastic elements
    have to compensate for these structures because they do not contribute to the contraction
  32. 4 non-contractile elements of muscle cells?
    -connective tissue

    -tendons

    -organelles

    -sarcolemma
  33. force of contraction) tension- internal?
    • need to overcome non-contractile elements
    • *most of the tension is geared toward picking up the slack of non contractile elements
  34. force of contraction) tension-external?
    overcome the actual load
  35. force of contraction) muscle length-length/tension relationship?
    the overlap between thick and thin should around 80 to 120 percent of resting sarcomere length.
  36. force of contraction) velocity and duration of contraction- load and duration (3)
    • the greater the load...
    • -the less the muscle shortens and
    • -the shorter the duration of contraction and
    • -the slower the contraction
  37. force of contraction) velocity and duration of contraction- fiber type- fast glycolytic- 5 characteristics
    -fast ATPase

    -less myoglobin

    -not depedent on oxygen

    -high glycogen storages

    • -little endurance
    • **used for sprinting
  38. force of contraction) velocity and duration of contraction- fiber type- fast oxidative glycolitic-  4 characteristics
    -fast ATPase

    -moderate glycogen stores

    -little endurance

    -some dependence on oxygen stores
  39. force of contraction) velocity and duration of contraction- fiber type- Slow oxidative- 6 characteritics
    -slow ATPase

    -lots of myoglobin

    • -many mitochondria
    • *capillaries also

    -Oxygen dependent

    -low glycogen stores

    -used for endurance
  40. function of smooth muscle
    squeezing and pushing of material through a tube
  41. what innervates the smooth muscle?
    autonomic nervous system
  42. what are the nerve endings called instead of terminal boutons?
    bulbous varicosities
  43. what is the smooth muscles nueromuscular junction called?
    diffuse junction
  44. histology of smooth muscle) how are the cells connected?
    gap junctions
  45. histology of smooth muscle) what surrounds each msucle cell?
    • endomysium
    • *connective tissue
  46. histology of smooth muscle) what 2 things differ in sarcoplasmic reticulum of smooth from skeltal?
    -it is less well developed

    -touches plasma membrane
  47. histology of smooth muscle) what does the plasma memebrane contain?
    caveoli
  48. histology of smooth muscle) what are caveoli?
    -cavities that contain calcium
  49. histology of smooth muscle) where is teh calcium stored?
    in sarcoplasic reticulum
  50. histology of smooth muscle) does it contain t-tubules?
    no
  51. histology of smooth muscle) what is the ratio of thick to thin?
    1:16

    **skeltal is 1:2
  52. histology of smooth muscle) what are the thick filaments made up off?
    myosin
  53. histology of smooth muscle) what are thin filaments made up off?
    actin and tropomyosin
  54. histology of smooth muscle) how are the thick and thin filaments oriented?
    spiral down the long axis of a muscle cell
  55. histology of smooth muscle) AP stimulus (4)
    -NT release from bulbous varicosity

    -SR receives the stimuls directly

    -CA enters the cytoplasm from SR and the caveoli

    -contraction can then occcur
  56. histology of smooth muscle)how does AP spread ?
    through the gap junctions
  57. mechanism of smooth muscle contraction) 5 steps
    -initiated by CA entry into cytoplasm

    • -CA binds to calmodulin
    • *intracell protein

    -calmodulin activates kinase

    -kinase trasnfers phosphate to myosin head

    -cross bridges form similarly to skeletal muscle
  58. 2 types of smooth msucle- single unit (3)
    -cells contract as a unit

    -gap junctions allow current flow directly

    -found in organs
  59. 2 type of smooth muscle- multi unit charaterisitics (5)
    -muscle cells are independent of one another

    -rare gap junctions

    -rare spontaneous APs

    -respond to hormones 

    -innervated by autonomic nervous system
  60. examples of multiunit smooth muscle?
    -msucles that regulate pupil size, arrector pilli, alrge airways of lungs, and larger arteries
  61. regulation of smooth muscle) What 2 NTs does it use?
    -acetylcholine

    -norepinephrine
  62. regulation of smooth muscle) what 2 things does its receptors do?
    • either inhibit or excite
    • *depedning on organ system the receptor will increase or decrease contraction
    • **ex) when resting smooth msucle can increase contractions, when running they can inhibit contractions
  63. regulation of smooth muscle) stretching?
    when stretched, mre vigorous contractions occur
  64. regulation of smooth muscle) hormone and local factors?
    it depends on the receptors, which will dictate if they are going to be stimuate of inbit
  65. unique features of smooth muscle) length tension
    when stretching, it stimulates contraction
  66. unique features of smooth muscle) hyperplasia
    increase # of cells
  67. unique features of smooth muscle) secretion (2)
    -secretes elastin and collagen of connective tissues

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