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Sliding Filament Theory


Sliding Filament Theory: 

The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. According to the sliding filament theory the myosin filaments of muscle fibres slide past the actin thin filaments during muscle contraction while the two groups of filaments remained at relatively constant at length.

 1. I bands are composed of actin filaments and the A Bands principally of myosin filaments.

2. during muscle contraction the actin filaments move into the A bands between the myosin filaments.

3. The backbone of a muscle fibre is actin filaments which extend from z line up to one end of H zone, where they are attached to an elastic component which is named as S filament.

4. Myosin filaments extend from one end of the A band through the H zone up to the other end of the A band.

5. Myosin filaments remain in relatively constant length during muscle stretch or contraction.

6. During stretching only I bands and H zone increase in length while A band remains same.

7. During contraction actin filaments move into the A bands and the H zone is filled up . The I band shorten and Z line comes in contact with the A band.

8. Myosin filaments are attached to Z line by titin protein.

9. Myosin and actin filaments lie side by side in the A band in the absence of ATP they do not form cost cross linkage.

10. The possible driving force of contraction is the actin and myosin linkages which depend on ATP hydrolysis by myosin.




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  1. UnknownMarch 8, 2022 at 9:41 AM

    thank you for helping me ,tomorrow i have cell biology exam ,after see your video lesson and this note i solve my problem ,thank you again ,how ever im 2nd year student some time i need tutor so plz uplode more video ,best of luck bay the way i watching your video from italy and im from bangladesh

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