PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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True
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False
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Either A or B
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None of the above
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Detailed explanation-1: -During muscle contraction, the I band is reduced in size as the overlap between the thick and thin filaments increases. Consequently, the H zone also decreases in length.
Detailed explanation-2: -The H zone-the central region of the A zone-contains only thick filaments and is shortened during contraction. The I band contains only thin filaments and also shortens.
Detailed explanation-3: -Sarcomeres are highly stereotyped and are repeated throughout muscle cells, and the proteins within them can change in length, which causes the overall length of a muscle to change. An individual sarcomere contains many parallel actin (thin) and myosin (thick) filaments.
Detailed explanation-4: -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-5: -So, the correct answer is ‘A-Band remains constant’.