Everyone, so this video is going to be a little bit different. Now, we know this chapter can be a bit confusing. There's a lot of new terminology, and a lot of fibers to keep track of. So, we're going to just put the anatomy aside for a second, and we have created an analogy where we're going to be imagining the sympathetic nervous system as like a subway train system. So, hopefully, this helps you kind of just take a step back and just understand conceptually what is happening within this nervous system. So, if we're imagining this as a train system, the nerve impulses are going to be the trains traveling along the tracks, and the tracks are basically nerve fibers. And then our spinal cord is going to be acting as kind of a central terminal where all of our trains are going to be originating from. So, if you look over here at our images, you see we have this kind of subway map here on the left and this very simplified anatomical image here on the right, and you can see in both images that the spinal cord is kind of acting as that central terminal where all of these nerve impulses or trains are going to be starting off from.
Next to that spinal cord, we have a structure called the sympathetic trunk. Now, don't worry about what that is, you'll learn all about it very soon, but for now, just know that it's basically like a parallel track. So, it's going to run parallel to the spinal cord that all of our trains, our nerve impulses, are going to use in some way. So, if we're looking at our images, we have the sympathetic trunk here on our subway map, and then this structure right here is our sympathetic trunk in that anatomical image, and again, it's going to be running parallel to our spinal cord.
Next, we have our ganglia, which are going to be acting as train stations. So, within these train stations, just like with a real train station, these impulses or these trains can either travel straight through them, or we can have a synapse in them. So, imagine you're like either switching trains or like catching a connector train. And I want to quickly draw your attention to this symbol right here, this kind of circle with this triangle next to it. I want you to imagine this as kind of like an axon and a dendrite, and we're going to be using that image to depict a synapse both in this video and in upcoming videos. So, just keep in mind, whenever you see that little triangle with the circle, we're talking about a synapse happening in that location. So, if we look at our maps, we have our little train stations here on our subway map, and then these kind of oval bulbous structures on that sympathetic trunk are the ganglia there. So, all those structures are ganglia. And again, you can imagine if you're on a train and it pulls up to a train station, you could just stay right on that train, and then it's going to keep moving again. That's like if that nerve impulse just passed right through. Or you can have that synapse catch, catching a connector train. So, you're on your train, it pulled up to a train station, you get out, you get on a different train, and then that train heads out. So, either one of those can happen within these locations.
And just as a quick reminder when we're talking about synapses here, we're going to be talking about chemical synapses, which are gaps between neurons that are specialized for communication via neurotransmitter. And if you need a refresher on that, we have a whole video on them in our chapter on nervous tissue. So, feel free to go check that out. And then, finally, we're going to have our effectors which are basically our ultimate destinations. So remember, effectors are just the organs or glands that are affected by the nerve impulse being sent out. So here, our heart, our lungs, our spleen, our liver, those are going to be our effectors, those final destinations that our nerve impulses are trying to travel to. And then one more cool thing to note about our autonomic nervous system is that all of these journeys from the spinal cord have to change trains or synapse one time, which means that every nerve impulse is going to travel through exactly two fibers. So you can see here on our map we have, like, fiber number 1, fiber number 2, fiber number 1, fiber number 2. So keep that in mind because that is a very important feature of our autonomic nervous system, and we see it both in our sympathetic division and in our parasympathetic division. Alright. So hopefully this is helpful as you move through and learn the anatomy in more detail. We're going to keep the color coding as consistent as possible. So the sympathetic trunk will always be yellow, the ganglia will always be green, etc. So, as you move forward, just remember that conceptually this is all that's happening here. We have these trains that are departing from our spinal cord. They're going to travel through that sympathetic trunk. They're going to travel through ganglia at some point, they're going to synapse eventually, travel through those two fibers, and eventually reach their final destination, those effector organs. Alright, so I will see you guys in our next video. Bye bye!