excitation-contraction coupling
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Created by:
icedrosebud on October 25, 2008
Subjects:
human biology, chapter, 10 exam 3
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24 terms
Terms | Definitions |
|---|---|
 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 |
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