PHYSIOLOGY
SARCOMERE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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I band
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M line
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H zone
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A band
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Detailed explanation-1: -Muscle contraction is brought about by sliding movement of actin filaments over myosin filaments. When a muscle fibril contracts, it’s A band remains constant and I band shortens. H – Zone disappears. M – line and Z – line also come closer.
Detailed explanation-2: -The H zone-the central region of the A zone-contains only thick filaments (myosin) and is shortened during contraction. The H zone becomes smaller and smaller due to the increasing overlap of actin and myosin filaments, and the muscle shortens. Thus when the muscle is fully contracted, the H zone is no longer visible.
Detailed explanation-3: -Within the A band, there is a relatively brighter central region, called the H-zone in which there is no actin / myosin overlap, when the muscle is in a relaxed state.