The sarcolemma of muscle fibers folds inwards and forms a system of tubes which run through the sarcoplasm called:
Correct answer: D. Transverse tubules
- A. Myofilaments
- B. Z-lines
- C. Sarcoplasmic reticulum
- D. Transverse tubules
Explanation
Transverse tubules, also known as T-tubules, are formed by the invagination of the sarcolemma into the sarcoplasm. They allow electrical impulses to quickly penetrate the interior of the muscle fiber, ensuring that the action potential triggers calcium release from the sarcoplasmic reticulum, leading to synchronized contraction of myofibrils. Myofilaments are involved in the contraction process but are not related to the tubular invaginations. Z-lines are structural components of sarcomeres, and the sarcoplasmic reticulum is involved in calcium storage and release, but neither is formed by sarcolemma folding.
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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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