Of these events, the first to occur when a motor neuron...

Of these events, the first to occur when a motor neuron stops sending an impulse to a muscle is the pumping of calcium ions out of the cytoplasm and back into the sarcoplasmic reticulum the release of myosin heads from the thin filament thin filaments slide back to their relaxed positions proteins on the thin filaments block actin's myosin-binding sites all of these events occur simultaneously

Transcript

00:01 Is a logical event must occur in order for muscle to relax relax in fact as i looked through all the options every one of them are required let me write down the order they are happening so obviously with the muscle contraction the active filament and myosine head they have this contact we call the cross bridge the cross bridge when it's over obviously you want to reverse the process then you can relax the muscle.

00:34 So you have reverse of crossbridge.

00:42 So their first event is going to be, first of all, it's going to be the ach, the acetocoline is released, release is stopped and broken down in a synaptic cleft.

00:58 Ach is stopped and excessive one will be broken down in the synaptic cleft.

01:13 We do not want acetycholine.

01:16 So they are being broken down by the enzyme called acetylcholineesteris.

01:25 So this is the first step.

01:28 So this actually prevent the further muscle fiber stimulation.

01:44 Again, the enzyme acetocolonesteris breakdown ach, the neural transmitter.

01:52 Second step.

01:54 Now, the calcium is removed from troponin and pumped back into the cycloplasmic reticulum.

02:19 And they are pumped back to sr.

02:27 The absence of the nerve pulse stops the release of calcium from sr.

02:32 The calcium atp is pumped actively transport the calcium back into the sr.

02:39 So this is being done by the pump, calcium atp pump.

02:44 Now, the next step, so the calcium, once it goes back into the sr, calcium binds to this cow sequestering, allowing sr to store large amount of calcium efficiently.

03:04 This is for storage during relaxation.

03:16 So this is for storage in sr...

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