Peripheral Nervous System

by Jason Amores Sumpter
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The purpose of the peripheral nervous system is to gather information and relay commands from the central nervous system. So it's gonna bring information to the C. N s and bring commands from the CNS out to the body. Now the peripheral nervous system is often divided into ah, bunch of different categories. So, uh, one of the major divisions is between what's called the somatic nervous system and the autonomic nervous system. Now the somatic nervous system is usually are frequently referred to as the motor system because it controls voluntary movements. It has two divisions the Afrin division and the different division half as in to if, as in away. So a front nerves carry sensory information from sensory receptors to the central nervous system, whereas different nerves carry signals from the central nervous system out to the body. And here you can see the skin has these nerves connected to it. Those air part of the Afrin division, they'll go to the spine, which is part of the CNS, And there they might connect with an E for it nerve that's going to go and form a neuromuscular junction on muscle. So, uh, it doesn't always work out this way. The point is, there are two divisions. Some effort nerves, air going Thio have their signals go all the way to the brain. Others will simply stop in the spinal cord. Here. I just want to point out the, uh this is the primary, some out of sensory cortex. Basically, that's where all the sensory information from the body is going to come in and just want to show that this is connected to, you know, particular pathway and spine and that will, uh, go radiate, you know, down And of course, nerves will exit through the bodies. Just want to show you that you know these Ephron Afrin nerves, they're all over the body. It's not just a small little loop like this image implies. Now, the autonomic nervous system regulates unconscious functions. So the motor system is voluntary muscle movements, right? Uh, the autonomic nervous system can result in muscle movements. However, these air not conscious functions there involuntary and unconscious functions. And the autonomic nervous system is really going to control organs of the endocrine system, the cardiovascular system, digestive system and excretory system. All the systems that we don't really have conscious control over right now in and of itself, the autonomic nervous system can be broken between two divisions. The sympathetic division and the Paris Sympathetic division. Actually, there's another division to the enteric division. You don't need to worry about memorizing this, but it is becoming a hotter subject of research now that we're understanding the importance of our guts. And this enteric division is going to control the organs of the digestive tract as well as the pancreas and gall bladder. Uh, I only bring it up again because, you know, you know me, I love gut bacteria. I think the whole enteric system is super cool and cutting edge research, right? So let's get to the stuff that you need. Thio. Make sure, you know, and that is the sympathetic and parasympathetic division these air, often a simplified as the fighter flight division and the rest and digest division. Now this simplification is pretty much good enough for our purposes. However, when you try to dealt, or if you, I should say, delve into greater detail in these matters, you'll see why it's not a perfect definition for our purposes. It's good enough, so the sympathetic division is going to have neurons that release nor epinephrine. And remember, that's going to trigger that fight or flight response. That's why this is the fighter flight division. And you can see what happens in the sympathetic nervous system down here. You know, dilation of pupils, uh, dry, mouth inhibiting slide of production, increasing heart rate and all stuff that air getting you're ready. Bought your body ready toe. Either run away or fight. You know, uh, tiger, or whatever it is. Now the parasympathetic division releases a Siegel coleene, and this is going to be the rest and digest division, and it's going to have some effects that are opposite, but not always. I don't want you to try to think of these. Two things is sympathetic, Does this And parasympathetic does the opposite because they don't really line up quite so perfectly. So there are some contrasts. For example, parasympathetic division constricts the people's as opposed to the sympathetic dilating them, but and you know likewise, it reduces heart rate is supposed to raising heart rate. Of course, it has other kind of unrelated things. Um, and you know, you concede e all of its activities here, and the reason just to give a little preview. The reason you sort of say, it's not a great you know, the rest digest fight or flight? Uh, division isn't perfect. You know, For example, when you look at reproductive functions, uh, rest and digest well, stimulating the genitals just doesn't really sound like rest, huh? But that's a parasympathetic function, so, you know, these aren't perfect definitions, but for our purposes, it's a good enough generalization. So with that, let's go ahead and flip the page.