PHYSIOLOGY
SKELETAL MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The sarcomere shortens.
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The A band remains constant in length.
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Actin and myosin do not shorten during contraction.
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Both actin and myosin myofilaments shorten during contraction.
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Detailed explanation-1: -Hence the correct answer is A) Actin and myosin filaments do not shorten but rather slide pass each other.
Detailed explanation-2: -Sliding Filament Model of Contraction 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-3: -Sliding-filament model of muscle contraction. The actin filaments slide past the myosin filaments toward the middle of the sarcomere. The result is shortening of the sarcomere without any change in filament length.
Detailed explanation-4: -Answer and Explanation: The statement that is false is d. sarcomeres increase in length during contraction. Sarcomeres are the smallest contractile units of muscles and they actually shorten, which causes muscle contraction.