BIOL 121 Chp 10: Muscular Tissue


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This is a lecture presentation for my BIOL 121 Anatomy and Physiology I students on Chapter 10: Muscular Tissue (Principles of Anatomy and Physiology, 14th Ed. by Tortora and Derrickson).

Rob Swatski, Associate Professor of Biology, Harrisburg Area Community College - York Campus, York, PA. Email:

Please visit my website for more anatomy and biology learning resources:

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BIOL 121 Chp 10: Muscular Tissue

  1. 1. 1   Muscular  Tissue   BIOL  121:  A&P  I   Chapter  10   Rob  Swatski   Associate  Professor  of  Biology   HACC  –  York  Campus   Textbookimages-Copyright©2014JohnWiley&Sons,Inc.Allrightsreserved.
  2. 2. 2   Myology   MoHlity   ContracHon   RelaxaHon   Chemical  energy   à  Mechanical   energy  
  3. 3. 3   Muscle   Tissue   Skeletal   muscle   Cardiac   muscle   Smooth   muscle  
  4. 4. 4   Skeletal   Muscle   A4ached  to   bone,  skin,   fascia   Striated  &   voluntary   Parallel  fibers  
  5. 5. 5   Cardiac   Muscle   Heart  muscle   Striated,   involuntary,   autorhythmic   Branching   fibers  
  6. 6. 6   Smooth   Muscle   In  walls  of   viscera   Nonstriated  &   involuntary   Tapered   individual   cells  
  7. 7. 7   FuncHons  of  Muscle  Tissue   Movement   Stability   Storing  and   TransporHng   Substances   Thermogenesis  
  8. 8. 8   ProperHes  of  Muscle  Tissue   Excitability   Extensibility   ContracHlity   ElasHcity  
  9. 9. 9   Skeletal   Muscle   Whole  muscle   =  organ   MulQnucleated   muscle  cell  =   fiber   Fascicle   Muscle  belly  à   Tendon  à   Bone  
  10. 10. 10   ConnecHve   Tissue   Components   of  Muscle   Epimysium   Perimysium   Endomysium  
  11. 11. Perimysium around fascicle Satellite cell Mitochondrion Endomysium Myofibril Muscle fiber Sarcolemma Sarcoplasm Nucleus OrganizaHon  of  a  fascicle  
  12. 12. 12   Tendons   Extensions  of  CT     A4ach  muscle   to  bone  or  to   other  muscle   Dense  regular   CT   Aponeurosis  
  13. 13. 13   Nerve  &   Blood  Supply   of  Muscle   Nerve,  artery,  1-­‐2   veins  per  muscle   Motor  neuron   supplies  several   fibers   Neuromuscular   juncHon  (NMJ)  
  14. 14. 14  
  15. 15. 15   Structure  of   Muscle   Fibers   Sarcolemma   Transverse  (T)   tubules   Sarcoplasm:   glycogen  &   myoglobin   Mitochondria  
  16. 16. Sarcoplasmic reticulum Sarcolemma Myofibril Sarcoplasm Nucleus Thick filament Thin filament Z disc Details  of  a  muscle  fiber   Triad: Transverse tubule Terminal cisterns Mitochondrion Sarcomere
  17. 17. 17   Myofibrils   Create  striaHons   Surrounded  by   sarcoplasmic   reHculum  (SR)   Thick  &  thin   contracHle   filaments  
  18. 18. 18  
  19. 19. 19   Sarcomeres   Organized   contracQle  units   Separated  by  z-­‐ discs   Thick  &  thin   filaments   overlap  
  20. 20. 20  
  21. 21. 21   Sarcomere   Structure   M-­‐line   H-­‐zone   A-­‐band   I-­‐band   Z-­‐disc  
  22. 22. 22  
  23. 23. 23  
  24. 24. 24  
  25. 25. 25   Myofibril   Proteins   ContracHle   proteins   Regulatory   proteins   Structural   proteins  
  26. 26. 26   ContracHle   Proteins   AcHn   Myosin  
  27. 27. Myosin-binding site (covered by tropomyosin) PorHon  of  a  thin  filament   Actin Troponin Tropomyosin
  28. 28. 28  
  29. 29. 29  
  30. 30. 30  
  31. 31. 31   Regulatory   Proteins   Troponin   Tropomyosin  
  32. 32. 32   Structural   Proteins   Nebulin:   alignment   TiHn:  extensibility   &  elasQcity   Myomesin:   anchorage   Dystrophin:   transmits  tension  
  33. 33. 33  
  34. 34. Sarcolemma Sarcoplasmic reticulum (SR) Transverse tubule Terminal cistern of SR Sarcoplasm Membrane protein Nucleus Z disc Dystrophin Thin filamentThick filament Sarcomere SimplisHc  representaHon  of  a  muscle  fiber   Myofibril = Ca2+ Key: = Ca2+ release channels = Ca2+ active transport pumps Glycogen granulesMyoglobinMitochondrion Z disc
  35. 35. 35   Sliding  Filament   Mechanism  of   ContracHon    
  36. 36. 36   NMJ   Axon  terminal  of   motor  neuron   SynapHc  end  bulb   Motor  end  plate   Synapse   SynapHc  cleW  
  37. 37. Neuromuscular  juncHon   Axon collateral of somatic motor neuron Axon terminal Synaptic end bulb Neuromuscular junction (NMJ) Sarcolemma Myofibril in muscle fiber Muscle fiber
  38. 38. 38   Muscle   ContracHon   Nerve  impulse   reaches  axon   terminal  at  NMJ   SynapHc  vesicles   à  ACh  into  cle   ACh  à  receptors   on  sarcolemma   (motor  end  plate)   Na+  channels   OPEN   Na+  “soaks”  into   muscle  fiber  
  39. 39. Enlarged  view  of  the  neuromuscular  juncHon   Axon terminal Nerve impulse Synaptic vesicle containing acetylcholine (ACh) SYNAPTIC END BULB Synaptic cleft (space) Ca2+ Voltage-gated Ca2+ channel Sarcolemma MOTOR END PLATE
  40. 40. Binding  of  acetylcholine  to  ACh  receptors  in   the  motor  end  plate   ACh is released from synaptic vesicle Synaptic cleft (space) ACh binds to ACh receptor Junctional fold Synaptic end bulb ACh is broken down MOTOR END PLATE Muscle action potential is produced Na+ Ca2+ 1 2 4 3
  41. 41. Nerve impulse arrives at axon terminal of motor neuron and triggers release of acetylcholine (ACh). 1 ACh diffuses across synaptic cleft, binds to its receptors in the motor end plate, and triggers a muscle action potential (AP). Acetylcholinesterase in synaptic cleft destroys ACh so another muscle action potential does not arise unless more ACh is released from motor neuron. ACh receptor Synaptic vesicle filled with ACh Muscle action potential Transverse tubule Muscle AP traveling along transverse tubule opens Ca2+ release channels in the sarcoplasmic reticulum (SR) membrane, which allows calcium ions to flood into the sarcoplasm. SR Ca2+ Ca2+ binds to troponin on the thin filament, exposing the binding sites for myosin. Elevated Ca2+ Contraction: power strokes use ATP; myosin heads bind to actin, swivel, and release; thin filaments are pulled toward center of sarcomere. Muscle relaxes. Troponin–tropomyosin complex slides back into position where it blocks the myosin binding sites on actin. Ca2+ active transport pumps Ca2+ release channels in SR close and Ca2+ active transport pumps use ATP to restore low level of Ca2+ in sarcoplasm. Ca2+ Nerve impulse 2 3 4 5 67 8 9
  42. 42. 42   Muscle   ContracHon   Muscle  acHon   potenHal  à   sarcolemma  &  T-­‐ tubules   SR  à  Ca+2  into   sarcoplasm   Ca+2  binds  to   troponin  
  43. 43. 43   Muscle   ContracHon   Tropomyosin   swivels  open   Exposes  myosin-­‐ binding  sites  (on   acQn)   ContracHon  Cycle   begins  
  44. 44. 44   ContracHon   Cycle   1.  ATP  hydrolysis   at  myosin  head   2.  Binding  of   myosin  heads  to   acHn   (crossbridges)   3.  ContracHon  =   power  stroke   4.  Detachment  of   myosin  heads  
  45. 45. 45   1.  ATP  hydrolysis    
  46. 46. 46   2.  Binding  of  myosin  heads  to  acHn  
  47. 47. 47   3.  ContracHon  =  power  stroke  
  48. 48. 48   4.  Detachment  of  myosin  heads  
  49. 49. Myosin heads hydrolyze ATP and become reoriented and energized Myosin heads bind to actin, forming cross- bridges As myosin heads bind ATP, the cross-bridges detach from actin Myosin cross-bridges rotate toward center of sarcomere (power stroke) ADP ADP ADP P P ATP ATP Key: = Ca2+ Contraction cycle continues if ATP is available and Ca2+ level in sarcoplasm is high 1 2 3 4
  50. 50. 50  
  51. 51. 51   ContracHon  
  52. 52. 52   RelaxaHon  
  53. 53. 53   Length-­‐ Tension   RelaHonship   Tension  =  force  of   contracQon   OpQmal   sarcomere  length   Overstretched   Understretched  
  54. 54. 54   Muscle   Metabolism   CreaHne   phosphate   Anaerobic   glycolysis   Aerobic  cellular   respiraHon  
  55. 55. 55   CreaHne   Phosphate   Made  from  excess  ATP  in   resQng  muscle   15  sec  =  maximum   contracQon   Short,  intense  bursts  of   energy  
  56. 56. 56   Anaerobic   Glycolysis   Makes  ATP  from   glucose   breakdown  during   glycolysis   If  no  O2:  Pyruvic   acid  à  lacQc  acid   à  blood   2  min  =  maximum   contracQon  
  57. 57. 57   Aerobic  Cellular   RespiraHon   Makes  ATP  from  glucose   breakdown  in   mitochondria   If  O2:  Pyruvic  acid  à   mitochondria  à  ATP   Several  minutes  to   hours  =  maximum   contracQon  
  58. 58. 58   Muscle   FaHgue   Feeling  Qred  &   wanQng  to  stop   exercise  =  central   faHgue   Low  Ach  &  Ca+2   Low  creaQne   phosphate   Low  O2  or  glycogen   Oxygen  debt   (recovery  oxygen   uptake)   Build-­‐up  of  lacQc   acid  
  59. 59. 59   Motor  Units   One  motor  neuron  +   10-­‐2000  muscle   fibers  (150  fibers   avg)   All  fibers  contract  in   unison   Strength  of  contracQon   depends  on:  the  size  of   a  motor  unit  &  the  #  of   fibers  ac4vated  at  a  give   4me  
  60. 60. 60  
  61. 61. 61   Control  of   Muscle   Tension   Twitch   contracHon   Brief  =  20-­‐200   msec   All  muscle  fibers  in   motor  unit  contract  in   response  to  AP  
  62. 62. Parts  of  a  Twitch   ContracHon   Latent   Period   ContracHon   Period   RelaxaHon   Period   Refractory   Period   62  
  63. 63. 63  
  64. 64. 64   Refractory   Period  
  65. 65. 65   Frequency   of   SHmulaHon   Wave  summaHon   Unfused   (Incomplete)   tetanus   Fused  (Complete)   tetanus  
  66. 66. Myograms Forceofcontraction (a) Single twitch (b) Wave summation (c) Unfused tetanus (d) Fused tetanus Time (msec) Action potential
  67. 67. 67   Wave   SummaHon  
  68. 68. 68   Unfused   (Incomplete)   Tetanus  
  69. 69. 69   Fused   (Complete)   Tetanus  
  70. 70. 70   Why  does   summaHon  &   tetanus  occur?   Ca+2  remains  in   sarcoplasm   ElasQc  components   (tendons,  CT)   remain  taut   Myotonic  goats!  
  71. 71. 71   Motor  Unit   Recruitment   Large  motor  units  à   High  tension   (Strength)   Small  motor  units  à   Low  tension   (Precision)   Motor  units  in  whole   muscle  fire   asynchronously     Why?  
  72. 72. 72   Muscle  Tone   Involuntary   contracQon  &   relaxaQon  of  small   #  of  motor  units   Alternate  in   constantly  shiing   pa4ern   No  movement   produced  (but   muscles  kept  firm)   FuncQons:  posture,   blood  pressure  
  73. 73. 73   Isotonic   ContracHon   Generates  movement   Concentric:  flexion   (muscle  shortens)   Eccentric:  extension   (muscle  lengthens)  
  74. 74. 74   Isometric   ContracHon   No  movement   Maintains  posture   Maintains  objects  in   fixed  posiQon  
  75. 75. 75   VariaHons  in   Skeletal   Muscle  Fibers   Differ  in  amount  of   myoglobin,   mitochondria,   capillaries   Red  muscle   (darker)   White  muscle   (lighter)   Range  of  contracQon   speeds  &  faQgue   resistance  
  76. 76. 76   3  Types  of   Skeletal   Muscle   Fibers   Slow  OxidaHve   (SO)   Fast  OxidaHve   GlycolyHc  (FOG)   Fast  GlycolyHc   (FG)  
  77. 77. Transverse  secHon  of  three  types  of  skeletal   muscle  fibers   Slow oxidative fiber Fast glycolytic fiber Fast oxidative– glycolytic fiber LM 440x
  78. 78. 78   Slow   OxidaHve   (SO)  Fibers   Smallest,   weakest,  slowest   (slow-­‐twitch)   Red  muscle:  lots   of  mito,  myo,  &   blood   Aerobic  cellular   respiraQon  à  ATP  
  79. 79. 79   Slow   OxidaHve  (SO)   Fibers   Sustained   contracQons   High  faQgue   resistance   Maintains  posture,   yoga  poses   Aerobic  endurance   acQviQes  (marathon   running)  
  80. 80. 80   Fast  OxidaHve-­‐ GlycolyHc   (FOG)  Fibers   Large  diameter  &   strength     Fast-­‐twitch   Red  muscle:  lots  of   mito,  myo,  &  blood  
  81. 81. 81   Fast   OxidaHve-­‐ GlycolyHc   (FOG)  Fibers   Aerobic  &   anaerobic   respiraQon  à   ATP  (store   glycogen)   Moderate   faQgue   resistance   Walking,   sprinQng  
  82. 82. 82   Fast   GlycolyHc   (FG)  Fibers   Strongest,  fast   twitch  fibers   High  glycogen   storage   White  muscle:  less   mito,  myo,  blood  
  83. 83. 83   Fast   GlycolyHc   (FG)  Fibers   Anaerobic   cellular   respiraQon  à   ATP   Low  faQgue   resistance   Rapid,  intense,   brief   contracQons:   weight  liing  
  84. 84. 84   Cardiac   Muscle   Tissue   Striated,   branching,   shorter  fibers  of   heart   Intercalated   discs  with  gap   juncHons   One  central   nucleus  per  fiber  
  85. 85. 85  
  86. 86. 86   Cardiac   Muscle   Tissue   Same  acQn  &   myosin   arrangement  as   skeletal  muscle   Autorhythmic   Longer   contracQons   (longer  Ca+2   delivery)  
  87. 87. 87   Smooth   Muscle   Tissue   Small,  single,   nonstriated,   tapered,   involuntary  fibers   No  T  tubules  &  li4le   SR   Contains  acQn  &   myosin,  but  no   sarcomeres   Dense  bodies  
  88. 88. Autonomic neurons Nucleus Muscle fibers (a) Visceral (single-unit) smooth muscle tissue (b) Multiunit smooth muscle tissue