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AimTo learn the structure of skeletal muscle
To be able to describe the neuromuscular junctionTo be able to
explain how muscles contract.The sliding filament theory.
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The neuromuscular junction (very
similar to synapse from CentralConceptsArrival of the
APstimulates therelease of aneurotransmitter (Ach), this bindson
surfacereceptors of themuscle causing aresponse.
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That response causes a Contraction
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This is what you need toexplain.
http://www.youtube.com/watch?v=Vlchs4omFDM
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Muscle histology
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O n a piece of A3 draw this diagram, give your self lots of room
to annotate. Also have Pg 38 open
Myosin
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actin
Add these labels
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actin troponin
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actin troponin
tropomyosin
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actin troponin
tropomyosin
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actin troponin
tropomyosinmyosin binding site
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Ca 2+Ca2+ Ca 2+ Ca
2+
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Ca 2+Ca2+ Ca 2+ Ca
2+
1. Calcium ions are released from the sarcolemma after
stimulation from the T system
How the muscle contracts:
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Ca 2+Ca 2+Ca 2+
Ca 2+
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Ca 2+Ca 2+Ca 2+
Ca 2+
2. the calcium ions bind to the troponin and changes its
shape
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Ca 2+Ca 2+Ca 2+
Ca 2+
3. the calcium ions bind to the troponin and changes its
shape
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Ca 2+Ca 2+Ca 2+
Ca 2+
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Ca 2+Ca 2+Ca 2+
Ca 2+
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Ca 2+Ca 2+Ca 2+
Ca 2+
4. the troponin displaces the tropomyosin and exposes themyosin
binding sites
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Ca 2+Ca 2+Ca 2+
Ca 2+
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Ca 2+Ca 2+Ca 2+
Ca 2+
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Ca 2+Ca 2+Ca 2+
Ca 2+
5. the bulbous heads of the myosin attach to the bindingsites on
the actin filaments : forming cross bridges
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Ca 2+a 2+Ca 2+
Ca 2+
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Ca 2+ Ca2+
Ca 2+
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Ca 2+ Ca2+
Ca 2+
6. the myosin heads change position to achieve a lower energy
state and slide the actin filaments past thestationary myosin
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Ca 2+ Ca2+
Ca 2+
AP i P iP i AP i P iP i AP i P iP i
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Ca 2+ Ca2+
Ca 2+ AP i P iP i
AP i P iP i
AP i P iP i
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Ca 2+ Ca2+
Ca 2+ AP i P iP i
AP i P iP i
AP i P iP i
6. ATP binds to the bulbous heads and causes it tobecome
detached
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Ca 2+ Ca2+
Ca 2+
AP i P iP i AP i P iP i
AP i P iP i
7. ATP binds to the bulbous heads and causes it tobecome
detached
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Ca 2+ Ca2+
Ca 2+
AP i P i
P i AP i P i
P i
AP i P i
P i
8. hydrolysis of ATP provides the energy to re-cock theheads
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Ca 2+ Ca2+
Ca 2+
AP i P i
P i AP i P i
P i
AP i P i
P i
9. hydrolysis of ATP provides the energy to re-cock theheads
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Ca 2+ Ca 2+ Ca 2+
AP i P i
P i AP i P i
P i
AP i P i
P i
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Ca 2+ Ca 2+ Ca 2+
AP i P i
P i AP i P i
P i
AP i P i
P i
10. calcium ions are re-absorbed back into the T system
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AP i P i
P i AP i P i
P i
AP i P i
P i
calcium ions are re-absorbed back into the T system
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AP i P i
P i AP i P i
P i
AP i P i
P i
11. the troponin reverts to its normal shape and thetropomyosin
move back to block the myosin binding sites
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AP i P i
P i AP i P i
P i
AP i P i
P i
the troponin reverts to its normal shape and the tropomyosinmove
back to block the myosin binding sites
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AP i P i
P i AP i P i
P i
AP i P i
P i
the troponin reverts to its normal shape and the tropomyosinmove
back to block the myosin binding sites
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AP i P i
P i AP i P i
P i
AP i P i
P i
12. Regeneration of ATP
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AP i P i
P i AP i P iP i
AP i P iP i
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AP i P iP i AP i P iP i
AP i P iP i
regenerates ATP
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Quiz &
Annimationhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and
_muscle_contraction.html
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R eview your worksheet of pictures, annotateeach picture
describing what is beingshown, using pages 38-41
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June 2002 Q6 (12 marks)
