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the link between the generation of a action potential (nerve impulse) in the sarcolemma and the start of a muscle contraction
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
contraction cycle step 3
cross bridges flexes (myosin head bends), moving the thin filament toward the middle of the sarcomere, called power stroke
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
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
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