Question

The H-Zone in the skeletal muscle fibre is due to ________

• A. Extension of myofibrils in the central portion of A-band.
• B. Central gap between actin filaments extending through myosin filaments in the A-band.
• C. The central gap between myosin filaments in the A-band.
• D. The absence of myofibrils in the central portion of A-band.

Answer 1

The correct option is B

Central gap between actin filaments extending through myosin filaments in the A-band.

Each muscle fibre has many parallelly arranged myofibrils contains many serially arranged units called sarcomeres.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 the thick filaments leaving the central part of the thick filaments. This central part of thick filament,not overlapped by thin filament is called H zone.