PHYSIOLOGY
MUSCLE CONTRACTION
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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troponin
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tropomyosin
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actin
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myosin
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Detailed explanation-1: -Thin filaments are composed primarily of the contractile protein actin. As illustrated in Figures 2-8, A and B, actin is composed of small globular subunits (G actin) that form long strands called fibrous actin (F actin).
Detailed explanation-2: -The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments. The myosin and actin filaments overlap in peripheral regions of the A band, whereas a middle region (called the H zone) contains only myosin.
Detailed explanation-3: -The thin filaments contain actin, tropomyosin, troponins C, I, and T and nebulin. The thick filaments are composed of myosin with the globular heads forming cross-bridges with thin filaments.
Detailed explanation-4: -Actin filaments (F-actin) are linear polymers of globular actin (G-actin) subunits and occur as microfilaments in the cytoskeleton and as thin filaments, which are part of the contractile apparatus, in muscle and nonmuscle cells (see contractile bundles).