PHYSIOLOGY
MUSCLE CONTRACTION
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Sarcolemma
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Sarcoplasmic Reticulum
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Thick Filament
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Thin Filament
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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 major protein components of smooth muscle thin filaments are actin, tropomyosin and caldesmon, present in molar ratios of 28:4:1 respectively. Other smooth muscle proteins which may be associated with the thin filaments in the cell are filamin, vinculin, alpha-actinin, myosin light chain kinase and calmodulin.
Detailed explanation-3: -Most of the cytoplasm consists of myofibrils, which are cylindrical bundles of two types of filaments: thick filaments of myosin (about 15 nm in diameter) and thin filaments of actin (about 7 nm in diameter).
Detailed explanation-4: -The major cytoskeletal protein of most cells is actin, which polymerizes to form actin filaments-thin, flexible fibers approximately 7 nm in diameter and up to several micrometers in length (Figure 11.1).