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  • Hi. It's Mr. Andersen. Today I'm going to talk about the fight or flight

  • reaction. This is one of my favorite videos on YouTube. This is from youtube.com/RussiaToday.

  • So we got this person here walking down the street. All of a sudden they realize there's

  • a car coming and then they get out of the way. Now if I were to keep playing it the

  • guy jumps out of the car, comes running in this direction. But basically I want to talk

  • about what's going on. So once this guy sees the car, how does he number one get out of

  • the way? And then how does that affect his body? How does that affect the organs and

  • the chemistry and all of that inside his body. And so that whole thing is called the fight

  • or flight. And so when I ask students, you know, how does he get out of the way of the

  • car? The answer is always adrenaline. And the right answer is no, it's not adrenaline.

  • Adrenaline is not going to be able to get there that quickly. And so how does the guy

  • really get out of the way? Well, he's going to see the car coming. He's going to process

  • that in his brain. And then he's going to send a message down his nervous system. That

  • nervous system is going to be attached to muscles. And those muscles are going to have

  • ATP ready to go. And so the way he's able to jump out of the way and not get hit by

  • the car, doesn't have anything to do with the fight or flight response. It's simply

  • his nervous system, his muscles and just responding to that threat immediately. But if you've

  • ever been in a situation like that, where you just barely survive an accident or something

  • like that, all of the sudden you feel this rush of just your heart starts beating fast

  • or your breathing. You feel warm. Now that's part of the fight or flight response. Because

  • this guy right here, since he's living in a city, is able to just kind of walk back

  • on to the road and keep about his business. But back in the day if you were attacked by

  • a mountain lion or somebody else, you had to fight now. You had to flee. Or you had

  • to attack the attacker. And so all of that is part of what's called the sympathetic nervous

  • system. Or that system inside our body that allows us to fight or flight. And so let's

  • zoom inside this guy and talk a little bit more about how are the fight or flight works.

  • And so it's basically centered around his brain. And so in the center of his brain,

  • near the bottom we have something called the hypothalamus. So the hypothalamus, in that

  • area of the brain, is essentially going to send a signal. Now that signal, not only are

  • we getting signals that are going to the muscles that allow you to move, but it's going to

  • send a signal all the way down a nervous signal all the way down here. Because in the center

  • of our adrenal gland we have something called the adrenal medulla. It's connected nervously

  • to the brain. So the moment he sees that car and realizes he might die, there's a signal

  • being sent to the adrenal medulla or the center of the adrenal gland. It's going to give off

  • what's called adrenaline. And that adrenaline is epinephrine. Epinephrine is a chemical

  • signal that is going to be attached to the circulatory system. And so it's going to course

  • through the body. So as his heart beats faster and faster and faster epinephrine is going

  • to flow throughout the rest of the body. Now epinephrine is not going to go into the cells

  • of the body. It's simply going to, if we say this is a big liver cell, it's simply going

  • to bind to proteins on the surface of those cells. And so what's it going to do to the

  • liver? Well in the liver what it's going to do is it's going to trigger a signal transduction

  • pathway that's going to convert glycogen, glycogen that's found inside the cells of

  • the liver. And it's going to use that as glucose. Why is it doing that? Well glucose is our

  • energy supply and so now glucose is going to be coursing through our body along with

  • epinephrine. And so now we have a supply of energy so we can quickly breakdown that glucose.

  • Get ATP and we can do more out of it. But what's interesting is that epinephrine is

  • going to go other places in the body. And it's going to have different responses depending

  • on where it goes. And so what is epinephrine going to do to the cells that are in control

  • of the breathing? The cells of the lung. It's going to speed up that breathing rate. What's

  • epinephrine going to do when it goes to the cells of the heart? It's going to speed up

  • the rate of the heart beat. And so it's going to trigger a signal transduction pathway in

  • the heart that's very similar to the signal transduction pathway that we find in the liver

  • cells. However it's going to have a different response inside the cells. It's going to not

  • release glucose, but it's going to increase the rate of the beating of those cardiac cells.

  • What do you think would happen to the digestive system? Well epinephrine is going to go there

  • as well. But what it's going to do is it's going to vasoconstrict. So it's going to slow

  • down digestion. And so it's going to slow down those blood vessels that feed those areas

  • that allow us to breakdown and digest food. Because when you're getting out of the way

  • of a car or fighting an attacker, you don't really need to concentrate on breaking down

  • that bagel that you ate for breakfast. So it's going to shut that down. But it's going

  • to go to the muscles of your body. And it's going to vasodilate. And so it's going to

  • move more blood to those areas. And so our whole body is designed so we can have one

  • signal, that epinephrine, but it can have all these different responses throughout the

  • rest of the body. And so that's going to allow our body to respond to that threat. And that's

  • why your heart races. You breathe faster. Your pupils dilate. All that happens and you

  • can thank epinephrine for that. And it's that chemical response and the different either

  • gene expression or signal transduction pathways that we have as a result. And so I hope that's

  • helpful.

Hi. It's Mr. Andersen. Today I'm going to talk about the fight or flight

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A2 epinephrine signal body adrenaline glucose flight

Fight or Flight Response

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    Bing-Je posted on 2013/12/13
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