NEET2016ZoologyLocomotion and MovementActual
The H-zone in the skeletal muscle fibre is due to
Options
- Athe central gap between actin filaments extending through myosin filaments in the A-band
- Bextension of myosin filaments in the central portion of the A-band
- Cthe absence of myofibrils in the central portion of A-band
- Dthe central gap between myosin filaments in the A-band.
Correct answer
A. the central gap between actin filaments extending through myosin filaments in the A-band
Step-by-step solution
Each muscle fibre has many parallely 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. Th