PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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According to the sliding filament theory, how does muscle contraction occur?
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Myosin heads form cross bridges and pull thin filaments, causing them to slide.
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Both thick and thin filaments shorten as the muscle contracts.
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A bands bunch up and shorten as myosin heads attach to thin filaments.
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Myosin heads attach and detach from thin filaments, causing thin filaments to shorten.
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Explanation:
Detailed explanation-1: -The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin. As soon as the actin-binding sites are uncovered, the high-energy myosin head bridges the gap, forming a cross-bridge.
Detailed explanation-2: -The sliding filament theory is a suggested mechanism of contraction of striated muscles, actin and myosin filaments to be precise, which overlap each other resulting in the shortening of the muscle fibre length. Actin (thin) filaments combined with myosin (thick filaments) conduct cellular movements.
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