I have studied that during a contraction of myofibril, the globular heads of myosin attach to actin filaments and pull them towards the centre of the sarcomere pulling the z line/disc as well. What I don't understand is that the z line must also in turn be connected to another sarcomere's actin filaments and they must also be getting pulled in the opposite direction by their myosin filaments. So how does the z line move in a particular direction?

  • $\begingroup$ What do you mean by particular direction? Do muscles ever move in a particular direction? $\endgroup$
    – Bryan Krause
    Commented Jan 26 at 15:43
  • $\begingroup$ What I meant was that th he sacromeres contract individually and the z lines get pulled by 2 opposite forces. Then how does the I band get shortened? Is it not by moving of the z line towards the centre ( towards A band)? $\endgroup$ Commented Jan 26 at 17:30


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