Define and draw a motor unit.

Video transcript

Hi, everyone. Let's look at our next question, which of the following structures is not a part of the neuromuscular junction A the axon terminals, B the junctional folds c the cell body or D the synaptic cleft. So let's recall that the neuromuscular junction is a specialized synapse between a motor neuron and a muscle fiber cell is the site of the transmission of the action potential. So we'll just look at kind of a simplified diagram of a neuromuscular junction to think about its parts and which of the answer choices might not be one of those. So I've got a kind of weird cylindrical structure on the top with a squiggly line next to it. There's a space between them and my squiggly line has little dots along the squiggles for lack of a better definition. So my sort of weird cylindrical shape here would be the axon terminal in a larger view. It would sort of come down to the muscle fiber and imagining a sort of almost looks like an arm with fingers. I've I'm doing another drawing here kind of coming down onto a cylindrical structure here and that will be my motor neuron coming down to meet the muscle fiber and the fingers or tentacle looking things at the end of it are called synaptic Bhutan part of the motor neuron where it comes down to that neuromuscular junction. So in my first drawing, a little cylindrical structure would be one of those synaptic buttons or the axon terminal since it's the end of the axon. So the axon terminals and choice a are definitely a part of the neuromuscular junction. I'm going to put a little check mark next to axon terminal since that is a part. So not our answer choice. So we can go ahead and cross that out. Choice. B is the junctional folds. And as you might guess, the junctional folds are these little wiggly line that I drew underneath my Exxon terminal, they are little folds lined with acyl coline receptors. Seal cole will be released by the axon that's going to cause our action potential. So those receptors are there for it to bind to. So those are the junctional folds and they are definitely part of the neuromuscular junction. So they can be eliminated as our answer choice. And then the final part of this junction is as we see, there's a space between the two, they don't actually come up against each other. And that space is the synaptic. So that is sort of the third component of our neuromuscular junction. So synaptic cleft is choice D. So JO D is not our answer either. So we're left with choice c by the process of elimination, which would be the cell body. So the cell body is not specifically part of the junction between the axon and the muscle fiber cell. So that is our answer to IC which structure is not a part of the neuromuscular junction. The cell body see you in the next video.