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Introduction to the Nervous System
Introduction to the Nervous System is a comprehensive course designed to provide a basic understanding of the biological and physiological aspects of the human nervous system. The course covers topics such as the central and peripheral nervous systems, neural receptors, and the location and function of the various brain structures. The course also examines the brain's primary roles in controlling and coordinating body movement, thought processes, and the formation of memories. Finally, the course overviews the neurological disorders that can affect the functioning of the human
Transcript
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I'm not going to go far into this but I hope that I turn a couple of you
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...blank
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at least into as big as nerds as I am. You think I'm kidding, I'm not. I
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have a Sheldon bobblehead on my on my bookcase in my office, that's
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what my friends call me is Sheldon, I'm like, "That's great, I hope I'm a little
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bit more personable." Anyway I hope I turn you into a couple nerds and
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after you take your kinesiology course and you passed your final, because I want
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you to pass your tests, you will look into some of this stuff, the
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nervous system, you literally could spend a lifetime studying a single aspect of
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the nervous system. Central nervous system is what? Brain and spinal cord.
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What is the function of your central nervous system? This is the thinking or
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the control center, even your spinal cord. Your spinal cord does a fair amount of
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"thinking." Here's an interesting experiment that I never want you to do.
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If you touch a hot stove, you ever done this? Everybody's done this,
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touched a really really hot object, you will pull your arm away before you have
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the conscious thought that it was painful. Fact. Part of that has to do with
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the fact that your pain pathway is slower than your muscular pathway. Part
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of that also happens because this is a withdrawal reflex and a reflex happens at
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the spinal cord level. Crazy huh? You touch something hot, your spinal cord
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doesn't even get the signal up here, goes "pink," then you go "ow." You don't go "owwww."
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That doesn't, it doesn't happen that way. Your peripheral nervous system
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is just the pathways in and out, that's it. That makes sense? So your peripheral
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nervous system is what we know of as nerves.
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You have you afferent and efferent nerves, you have your sciatic nerve,
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what's your sciatic nerve? Yeah, it goes down your leg, it's a group of axons.
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Axons go to neurons, but those axons are part of your your peripheral
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nervous system. Afferent means what? Goes in yeah, efferent exits. Good call.
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Efferent, E, exits. Efferent go to muscles for the most, as far as we're
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concerned for now, they also go to organs and stuff Afferent is sensory
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receptors. Everything from our eyes which we know as a sense, to touch, to even
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little receptors inside of joints that tell us how much pressure is within that
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joint, what position it's in. You might have heard of muscle spindles
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and Golgi tendon organ, that's all afferent information. So neural control
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of human movement, receive information. When you think of motion, you could
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break it down to receive information from sensory afferents, interpret
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organize and plan, and then activate motor units via of the motor nerve. So
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you have to sense your environment and then react to it, your body is
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continuously doing that. The complexity of that is staggering. The fact that we
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move at all sometimes is just staggering to me, all of this stuff working together,
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and how if you mess any of that up at all, that all changes. So what is a motor
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unit? Anybody? Let me take a step back, how much you think I can
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curl. Be generous.
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30s? That's not generous, I'm 6 foot 3, 225 pounds. 70s? Now you're being too generous
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but thank you, that's at least a little closer. I think with 70s with bad form, I
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could swing some 70s up. Yeah. Do you even lift?! You know who I'm
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talking about? You ever watch Bro Science Life? You have to watch this guy,
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This guy is hilarious, he's created a character around the worst gym bro that
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you can possibly think of. He is on a whole other level hilarious. He has a
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whole video on how to get out of leg day, you get what I'm saying?
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That's who this guy is, he'll go over the squat rack and start doing
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curls with the barbell. It's awesome. Anyway, so maybe I
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could cheat curl 70, let's say I could curl 60s, 50s probably with good form,
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so then the question becomes when a muscle fiber fires it fires completely.
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There's no dimmer switch on a muscle fiber. You kind of know this.
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You hit the the threshold, the activation threshold, create an action
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potential, the muscle fiber fires, it contracts. It doesn't go "little
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contraction," it just contracts. So then the question becomes if I can curl 60s, I
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can generate that much force, how do I curl this marker without throwing it
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through the ceiling? You get the the problem here? If I put 60, lifting 60
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pounds worth of force under this marker, what would happen?
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Yeah so that's a problem. How do I control that? How many fibers I recruit.
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Now how my body organizes that is through something called a motor unit. So
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you're exactly right, the only thing is is we don't have a nerve going to every
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fiber. That actually doesn't make sense. What your body's done is it's, you see
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how this is worked out? This is a nerve and I'm going to attach that to four
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fibers, so when that nerve fires, all four of those fibers
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will fire. And I might have bigger motor units than that, that have 100
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fibers, 120 fibers, my curling 60 fibers, and I may have a couple fibers there are
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only one, for really finite movement. Does that make sense? So based on how many motor
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units I recruit and what type of motor units I recruit will be dependent on what
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type of force I apply. Just remember, as soon as that motor unit fires, it does
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what? Fires completely, it contracts as hard as it can. That's it, on off. You'll
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find that a lot of things in the body are on/off, yes/no, facilitate/inhibit,
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works a little like a computer, right? 0 1.
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Neuromuscular efficiency. This is a little foreshadowing. I know this
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morning I'm doing a lot of foreshadowing, giving you a little bit of why you
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need to keep up with this. This is the definition of neuromuscular efficiency:
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the ability of the neuromuscular system to allow agonists, antagonists, stabilizers
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and neutralizers -which if you haven't learned that yet you will tomorrow or
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you will later in your class, those are the different roles a muscle
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can play - to work synergistically to produce, reduce and dynamically stabilize
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the entire kinetic chain in all three planes.
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You got part of that definition down already, you know the all three
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planes part. Now we just got to fill in the rest. All right so there's a little
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workbook page in there called "Putting It All Together. I think the workbook page
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is actually even nicer than that is, in the essence that you have a word
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bank in the bottom. I want you to take a couple minutes and fill that in.
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Alright so the blank receives information from the environment,
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organizes that information and initiates a motor program. The nervous
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system. Movement occurs when a muscle contracts, the muscles pull on? Yes
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tendons. Everybody always goes bones, and I'm like um. The tendons, in turn, pull on
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bones, the bones move as dictated by the joint type and structure, joints are
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supported by ligaments which connect bone to bone. Now if you're going to get
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really nerdy, part of this is putting in your reps. You know what I'm talking
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about? You put in your reps at the gym right, how many you guys go to the gym,
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regular basis, good, good. Good everybody should go to the gym, we need to be
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healthy. You got to put your reps in at the gym, you got to do your work.
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Part of knowing this stuff is doing your reps as well. So one thing you can
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start doing to yourself is imagine if you just thought about that for one
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joint motion. Let's say I did a curl, what muscles will do elbow
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flexion? What if, if we wanted to take it one further which I know is not for this
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class, what nerve innervates those muscles? Oh oh right what are the tendons?
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Tendons are going to be named after the muscles that's not too hard but at least
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be able to visualize what those tendons look like. What joint does it cross? Let's
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just pick one, we said elbow, what are the names of all the ligaments that
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cross the elbow? You get what I'm saying?
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Imagine if you did that and you just took one joint a day,
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one joint action a day. How long would that take you? 20 minutes maybe, you got
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Google, you got Google and my website, you have it easier than
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the previous generation who would have to go to the library look this stuff up in
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several text books. Imagine if you did that with one joint, just sat
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down wrote it out, you tried as much as you could by memory right, and then
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you found the rest on Google and wrote it down. The next day you tested yourself
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on that joint to make sure you remembered it, and did one new joint. How
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long would that take? 20 minutes a day. How good would you be at your anatomy at
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the end of one year? You'd be crushing. You would look at any
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kinesiology class and go I got this, it wouldn't even be a problem.
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