According to sliding filament theory, when muscle fibers are stimulated by the nervous system, which of the following changes occurs?
Correct answer: A. I-bands shorten
- A. I-bands shorten
- B. H-zone becomes more visible
- C. Z-lines move further apart
- D. A-bands shorten
Explanation
I-bands shorten: This option is the correct answer. According to the sliding filament theory, when muscle fibers are stimulated by the nervous system, the I-bands, which are light-colored regions within a sarcomere containing only actin filaments, shorten. This occurs due to the sliding of actin filaments over myosin filaments during muscle contraction.
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About Support and Movement
Support and movement covers the axial and appendicular skeleton, bone structure, joints and the arrangement of skeletal muscles. Muscle contraction is explained through actin, myosin, sliding filaments, calcium ions and ATP, while arthritis is distinguished as a disorder of joints rather than a normal part of movement.
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