What is happening inside the sarcomere during the relaxation phase of a muscle twitch? Calcium release from the SR is greater than its reuptake. Calcium reuptake is greater than calcium release causing the muscle to relax. The myosin heads are exhibiting active cross bridge cycling and the sarcomere is shortening. The actin thin filaments are relaxing and becoming shorter.
Added by Melissa C.
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Step 1: The action potential that triggered the twitch ends, so SR Ca2+ release through ryanodine receptors declines. Show more…
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Adi S.
Calcium ions are released from the sarcoplasmic reticulum. What happens next? (a) acetylcholine is released (b) active sites on the actin filaments are exposed (c) filaments move past one another, and the muscle fiber shortens (d) myosin is activated (e) $\mathrm{P}_{i}$ is released, and the cross bridge flexes
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