Which is most likely to extend the entire length of a muscle fiber?
Correct answer: B. Myofibril
- A. Sarcomere
- B. Myofibril
- C. Myosin filament
- D. M-line
Explanation
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 that extend from the myosin filaments and cyclically interact with the actin filaments as ATP is hydrolyzed. Each myofibril is about one or two micrometers (1 micrometer = 106 meters) in diameter and extends the entire length of the muscle fiber.
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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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