PHYSIOLOGY
MUSCLE CONTRACTION
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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H
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Z
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synaptic cleft
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sarcomere
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Detailed explanation-1: -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-2: -During contraction, the myosin heads extend from the thick filament surface and attach to actin in the thin filaments, causing the filaments to slide past each other in a cyclic, ATP-driven process.
Detailed explanation-3: -When (a) a sarcomere (b) contracts, the Z lines move closer together and the I band gets smaller. The A band stays the same width and, at full contraction, the thin filaments overlap. When a sarcomere shortens, some regions shorten whereas others stay the same length.
Detailed explanation-4: -Titin may be involved in fulfilling this task. Titin anchors myosin filaments to the Z-disc, and two titin molecules connect to each actin filament within the Z-disc [24].