MUSCLE NERVE CARTILAGE BONE
SKELETAL MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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pulled outwards thereby increasing the length of sarcomere
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compressed perpendicularly thereby decreasing height of sarcomere
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elongate perpendicularly thereby increasing height of sarcomere
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pulled inwards thereby causing shortening of sarcomere
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Detailed explanation-1: -As the Z lines come closer together, the sarcomere shortens. So, the sarcomere, the I band, and the H zone decrease in length during muscle contraction. However, the A band does not change length during muscle contraction, since its length is the same as the length of the thick filaments.
Detailed explanation-2: -The Z-lines are pulled closer together during contraction and move further apart during relaxation. The Z-lines are closer during contraction because actin and myosin interaction generates cross-bridges, which slide the myofilaments over each other.
Detailed explanation-3: -Sarcomere shortening is the result of cyclic cross-bridge formation between the myosin “head” formed by the myosin heavy chain (MHC) and active sites on actin. The process is regulated by the thin filament associated proteins, troponin (Tn) C, I, and T, and tropomyosin.