MUSCLE
SKELETAL MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Z-lines move apart during muscle relaxation because
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Calcium ions are added to troponin in actin filaments
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Calcium ions are added to tropomyosin in actin filaments
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Calcium ions are removed from troponin in actin filaments
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Calcium ions are removed from tropomyosin in actin filaments
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Explanation:
Detailed explanation-1: -Powered by ATP, it pumps calcium ions back into the sarcoplasmic reticulum, reducing the calcium level around the actin and myosin filaments and allowing the muscle to relax.
Detailed explanation-2: -When calcium binds to troponin, the troponin changes shape, removing tropomyosin from the binding sites. The sarcoplasmic reticulum stores calcium ions, which it releases when a muscle cell is stimulated; the calcium ions then enable the cross-bridge muscle contraction cycle.
Detailed explanation-3: -(2) Calcium binds to troponin C, which induces a conformational change in the troponin complex. This causes tropomyosin to move deeper into the actin groove, revealing the myosin-binding sites.
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