The H-zone in the skeletal muscle fiber is due to the:
Correct answer: A. Central gap between actin filaments extending through myosin filaments in the A band
- A. Central gap between actin filaments extending through myosin filaments in the A band
- B. Extension of myosin filaments in the central portion of the A band
- C. Absence of myofibrils in the central portion of the A band
- D. Central gap between myosin filaments in the the A band
Explanation
Each muscle fiber has many parallelly arranged myofibrils. Each myofibril contains many serially arranged units called sarcomere which are the functional units. Each sarcomere has a central 'A' band made of thick myosin filaments and two half 'I' bands made of thin actin filaments on either side of it marked by 'Z' lines. In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments. This central part of the thick filament, not overlapped by thin filaments is called the 'H' zone.
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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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