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24 terms

excitation-contraction coupling

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excitation-contraction coupling
the link between the generation of a action potential (nerve impulse) in the sarcolemma and the start of a muscle contraction
step 1 of excitation-contraction coupling
action potential travels along the sarcolemma
step 1 a of excitation-contraction coupling
causes the release of calcium into the sarcoplasm from the terminal cisternae of the sarcoplasmic reticulum
binds to troponin, which causes tropomyosin to move in between the strands of actin
step 1 b of excitation-contraction coupling
step 1 c of excitation-contraction coupling
exposes the binding sites on the actin
contraction cycle step 1
ATP splits- into ADP (adenosine diphosphate) and a phosphate group
head of myosin attaches to the binding sites (cross bridges)
contraction cycle step 2
contraction cycle step 3
cross bridges flexes (myosin head bends), moving the thin filament toward the middle of the sarcomere, called power stroke
power stroke
contraction cycle step 3
contraction cycle step 4
ATP binds with the myosin head, which releases the myosin head from the actin
energy from ATP is released by splitting, causing the myosin head to return to its original position
contraction cycle step 4 a
contraction cycle step 4 b
myosin is cocked and ready to bind with actin again
relaxation step 1
when nerve impulse stops, release of ACh stops
relaxation step 1 a
calcium is returned to the terminal cisternae-requires energy (ATP)
relaxation step 1 b
when calcium is taken back by the SR, troponin changes shape and tropomyosin once again covers the binding sites on the actin
muscle relaxes
relaxation step 1 c
cycle repeats many times during one contraction of a muscle
relaxation step 1 d
ADP
adenosine diphosphate
adenosine triphosphate
ATP
NMJ
neuromuscular junction
acetycholine
ACh
AChe
acetycholinesterase
acetycholinesterase
the eraser
sarcoplasmic reticulum
SR