Answer
1.The synoptic knob stops releasing ACH because nerve signals have stopped arriving at the synapse.
2. The ACH that was bound to ACH receptors dissociate and the molecules break down or are catabolized by ACHesterase. Fragments of ACH are resorbed by the synoptic knobs for reuse. As a consequence, stimulation of the muscle fibers ceases.
3. Since the nerve fiber has ceased firing, Ca++ release from the sarcolemma ceases, but its resorption continues. The absorbed Ca++ binds to calsequestrin in the SR. As the level of calcium in the sarcoplasm falls, more and more calcium is displaced from troponin without replacement As a result, tropomyosin resumes its original conformation -- before the binding of Ca++by troponin. In this original conformation tropomyosin once again blocks the active sites of actin.
Work Step by Step
When myosin can no longer bind to actin the muscle loses tension. Later stretching will return the muscle to its original length
