PHYSIOLOGY
SLIDING FILAMENT MODEL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Why are calcium ions important to muscle contraction?
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calcium causes ATP to bind to actin
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calcium allows for the binding of myosin and actin
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calcium increases the action potential along the sarcolemma
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calcium releases the Z-disks
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Explanation:
Detailed explanation-1: -Calcium triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin. Two different regulatory systems are found in different muscles.
Detailed explanation-2: -If present, calcium ions bind to troponin, causing conformational changes in troponin that allow tropomyosin to move away from the myosin binding sites on actin. Once the tropomyosin is removed, a cross-bridge can form between actin and myosin, triggering contraction.
Detailed explanation-3: -The primary role of calcium ions in the sliding filament theory is to bind to tropomyosin, changing its shape and moving it away from myosin binding sites.
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