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SKELETAL MUSCLE NOTES

SKELETAL MUSCLE NOTES. Terms. epi = upon peri = around endo = within or inner mys = muscle sarco = flesh lemma = husk fasci = bundle. Structure of skeletal muscle fiber. A sarcomere. Many packages of Twizzlers = Fascicle. Twizzler analogy. 1 package of Twizzlers = Muscle fiber

evan-hopkins
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SKELETAL MUSCLE NOTES

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  1. SKELETAL MUSCLE NOTES

  2. Terms • epi = upon • peri = around • endo = within or inner • mys = muscle • sarco = flesh • lemma = husk • fasci = bundle

  3. Structure of skeletal muscle fiber

  4. A sarcomere

  5. Many packages of Twizzlers = Fascicle Twizzler analogy

  6. 1 package of Twizzlers = Muscle fiber The packaging = Sarcolemma Twizzler analogy 2

  7. 1 bundle of twizzlers = myofibril Twizzler analogy 3

  8. 1 Twizzler strand = Filament Twizzler analogy 4

  9. Terms associated with skeletal muscles • Tendon- Attaches muscle to bone

  10. Ligament- Attaches bone to bone

  11. Origin- The location where the muscle is attached to the relatively immovable end of the bone

  12. Insertion- end of the muscle that is attached to the movable bone

  13. Prime mover- the muscle that provides most of the movement

  14. Synergist- muscle that assists the prime mover

  15. Antagonist- the muscle that opposes the action of the prime mover

  16. Muscle Contraction

  17. Neuromuscular Junction

  18. Neuromuscular junction animation • animation

  19. Sliding Filament theory • Boat = Myosin (thick filament) • Oar = Myosin side arm • Water = Actin (thin filament) • Life ring = Calcium

  20. Resting • ATP is bound to myosin side arm. • ATP cleaves into ADP + P (high energy)

  21. Step 1 Action potential • A nerve action potential releases acetylcholine into the synaptic cleft opening the Na+ channels. • Action potential spreads across sarcolemma releasing Ca into sarcoplasma

  22. Step 2 Myosin-actin binding • Ca binds to troponin • A shape change in troponin moves tropomyocin out of the way of actin binding site • Actin and myosin bind using energy from cleaved ATP.

  23. Step 3 Power Stroke • Side arm pivots so myosin and actin slide by each other shortening the sarcomere. • ADP and P released (low energy)

  24. Step 4 ATP binding and actin-myosin release • A different ATP molecule binds to active site. • Actin released

  25. Step 5 ATP cleavage • Return to high energy state • Cycle will repeat if Ca still available.

  26. A few thoughts • The boat (myosin) does not move far in one cycle, a muscle contraction requires many cycles • What happens if ATP is not available? • Muscle stays contracted- cramps • Why does rigor mortis occur? • ATP is not available to control Ca release so contractions are continuous 6-8 hours after death. Body relaxes 16-24 hours as enzymes break down contractile structures

  27. Sarcomere summary

  28. Final animation • animation 2 • Watch “Distonia: movie

  29. Muscles of the Head

  30. Anterior torso muscles

  31. Posterior torso muscles

  32. Anterior shoulder and arm

  33. Anterior forearm

  34. Anterior thigh

  35. Lateral thigh

  36. Posterior thigh

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