MUSCLE
SKELETAL MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Thin filaments shorten; thick filaments lenghten
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Thick filaments shorten; thick filaments lengthen
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The filaments slide past one another
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Both filaments shorten
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Detailed explanation-1: -For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments-the components of sarcomeres-do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.
Detailed explanation-2: -Muscle contraction occurs when the thin actin and thick myosin filaments slide past each other. It is generally assumed that this process is driven by cross-bridges which extend from the myosin filaments and cyclically interact with the actin filaments as ATP is hydrolysed.
Detailed explanation-3: -According to the sliding filament theory, a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber. When all the sarcomeres in a muscle fiber shorten, the fiber contracts.