Fill in the missing steps for skeletal muscle contraction by...

Fill in the missing steps for skeletal muscle contraction by writing the correct number in the blank (write only the number; not the whole statement). 1. acetylcholine diffuses across the synaptic cleft and binds receptors on the muscle fiber 2. neuron axon terminal releases acetylcholine by exocytosis 3. myosin head pivots, pushing thin filament toward center of sarcomere (power stroke) 4. exposes active site on actin (thin filament) 5. action potential releases calcium from sarcoplasmic reticulum 6. sarcomere shortens Neuron fires an action potential -> [ ] -> [ ] -> muscle fiber fires an action potential -> [ ] -> [ ] -> myosin head binds actin (cross-bridge formation) -> [ ] -> [ ] -> myofibril shortens -> muscle fiber shortens -> muscle shortens (contracts)

Transcript

00:01 Hello everyone in this question we will be talking about the skeletal muscle contraction okay so there is first step is that action potential arrives at the axon terminal okay so at the axon terminal an action potential arrives okay suppose here the action potential arises is due to which the voltage gated calcium channel opens.

00:37 So here suppose there is calcium, voltage gated calcium channel.

00:43 So from this, the calcium enters into this.

00:48 Okay, so here calcium will enter.

00:51 After this, the calcium dependent fusion with synaptic vesicle will occur.

00:58 Okay so here we have synaptic vesicles present okay so these calcium will fuse with the synaptic vesicles okay and due to the calcium present these synaptical vesicles will fuse with the membrane okay and after the fusion of the synaptic vesicles with the membrane there will be the release of synaptic vesicles by exocytocytes by exocytoc.

01:28 So in the synaptic vesicles we have neurotransmitter that is acetylcholine in this case.

01:38 Okay, so here acetylcholine is present in this synaptic vesicle that is our neurotransmitter.

01:49 Okay, so this is acetylcholine.

01:54 Okay.

01:55 Now these synaptic vesicles will different.

01:58 Fuse across the synaptic clef and binds to receptor present at the post -synaptic neuron.

02:08 Okay, this is our pre -synaptic neuron and now the synaptical vesicle will fuse with the post -synaptic neuron.

02:17 Okay, this is post -synaptic neuron and this is presynaptic neuron, okay? and here we have here synapsis occurs, okay? so these synaptic vesicle will fuse here and due to which there is binding and due to which the opening of channels occurs across the membrane.

02:41 So here the sodium channels will be open and there will be depolarization.

02:49 So here calcium will move.

02:52 Here calcium will move out from the sarco.

02:56 Okay and due to which there is muscle contraction okay and in the muscle contraction basically it's that the signal from nerve triggers the action potential in the sarkomere okay and then this action potential propagates through the t -tibules okay and then calcium channel opened in sarkoplasmic reticulum okay then after after this there is contraction of myofibril.

03:32 So basically when 4 calcium binds with the troponin c, the troponin i, that is the inhibitor release its whole to actin.

03:44 And now tropomyosin can bind with the actin filament...

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