In presence of muscle contraction, _ is brought closer, _ shortens and _ disappears.
Correct answer: C. Z-line, I-band, H-zone
- A. Z-line, H-zone, I-band
- B. I-band, Z-line, H-zone
- C. Z-line, I-band, H-zone
- D. H-zone, I-band, Z-line
Explanation
The mechanism of contraction is the binding of myosin to actin, forming cross-bridges that generate filament movement. When a sarcomere contracts, the Z lines move closer together and the I band gets smaller, and the H-zone disappears. The H-zone refers to a region within the sarcomere where only thick filaments (myosin) are present. It is located in the center of the sarcomere, between the thin filaments (actin) of adjacent sarcomeres. During muscle contraction, the H-zone narrows as the thin filaments slide inward and overlap with the thick filaments.
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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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