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Biology: Endocrine Function: Hormone Oscillations


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About this Lesson

  • Type: Video Tutorial
  • Length: 9:39
  • Media: Video/mp4
  • Use: Watch Online & Download
  • Access Period: Unrestricted
  • Download: MP4 (iPod compatible)
  • Size: 103 MB
  • Posted: 07/01/2009

This lesson is part of the following series:

Biology Course (390 lessons, $198.00)
Biology: Animal Systems and Homeostasis (63 lessons, $84.15)
Biology: The Endocrine System (3 lessons, $18.81)

Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis.

George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology, Chemistry, Political Economics, and Physical Education in the Peace Corps. Since then, he's taught in the Western NY region, spending the last 20 years in the Rochester City School District where he is the Director of the Loudoun Academy of Science. Besides his teaching career, Mr. Wolfe has also been an Emmy-winning television host, fielding live questions for the PBS/WXXI production of Homework Hotline as well as writing and performing in "Football Physics" segments for the Buffalo Bills and the Discover Channel. His contributions to education have been extensive, serving on multiple advisory boards including the Cornell Institute of Physics Teachers, the Cornell Institute of Biology Teachers and the Harvard-Smithsonian Center for Astrophysics SportSmarts curriculum project. He has authored several publications including "The Nasonia Project", a lab series built around the genetics and behaviors of a parasitic wasp. He has received numerous awards throughout his teaching career including the NSTA Presidential Excellence Award, The National Association of Biology Teachers Outstanding Biology Teacher Award for New York State, The Shell Award for Outstanding Science Educator, and was recently inducted in the National Teaching Hall of Fame.

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Recent Reviews


You make the subject fascinating and fun to learn about! Thank you!


You make the subject fascinating and fun to learn about! Thank you!

One of the things that I really want to stress to you guys is that this whole idea of homeostasis is not stability and hormones are no different. Yeah, I know, you're saying to yourself, "Well, isn't the job of the endocrine system to provide constant amounts of hormones?" Well, do you supply anything constantly to your body? Why should your body do the same thing? You see, the point is, take something, for example, like the way we metabolize our foods. You sit down, eat a meal, and then you don't eat for eight more hours, and so what's going to happen, is stuff is going to go up and stuff is going to go down, and then stuff's going to go up, stuff's going to go down, and the hormones made to metabolize those products are going to go up and down, and up and down, and up and down. So, really what we have is that hormone levels form an oscillation. Just think back to that thyroid stimulating hormone. That wasn't on or off. That was like, thyroid hormone went up, and then it inhibited and it went down. And then it went up and then it went down. And as long as you fall within that normal oscillation, you're okay. So, any given time, I could take a blood sample from your, measure hormones, and minutes later, they would be lower or higher. And that way we could graph this nice little up and down curve and figure out what's a normal event.
Well, that brings to mind a good story. You guys, you know, you probably have really crummy diets. If you're like most students around this country, and probably as you sit here listening to this wonderful discussion, you're eating a donut or candy or something like that. And, for me, I know that donuts are poison to me in the morning. I mean, if I go and I eat a donut, all of a sudden, I'm like (descending sound), I mean I'm no good. And then, like within an hour, I'm like (hyperactive sound), and then I'm like (descending sound) and then.... And then I go through this cyclic thing. And being a biologist, I know what's going on there and it really makes me angry because I shouldn't have eaten that stupid donut. And here's what's happened.
Let me show you the way we metabolize sugar. And a couple of very cool hormones that do this. I want to start out with, we'll go to metabolize glucose. Let's start with insulin. So I just ate a donut. Or you eat a regular old meal. And your pancreas produces insulin. And what's the purpose of insulin is two-fold. Number one, it takes sugar and moves it into the liver where it's going to end up as glycogen. So it's going to take the glucose and it's going to store it as glycogen in the liver, and it's going to open up cells to glucose uptake. So, it's going to take glucose and put them in the cells. And what's that going to cause? That's going to cause your blood glucose level to decline to a regular point. And then what's going to happen is you're going to stop storing that sugar, and that's good. And your blood sugar level is going to go down, and that's good. But then, say you don't eat for a while, and your blood sugar - and you know this, sometimes if you don't eat for a while, you get a little shaky. And there's a reason for that. You don't have any sugar.
So then what happens - now we'll go to the glucagon. Now what happens is the pancreas makes another hormone, glucagon. And glucagon goes to the liver and causes you to release sugar into your blood so that it can be secreted around your body. So, the blood glucose level rises to a set point and then the glucagon is going to go down because it's going to reach that point. So, in essence, the glucose level is talking to the pancreas. You see? Your blood is talking to your pancreas. Your pancreas is talking to your liver or your pancreas is talking to your liver and your regular cells. Everybody is talking and life is good. Until you eat that donut. Then, let's see what happens. Or a candy bar.
Let's talk about evolution. Do you think our ancestors ate a lot of donuts? Or a lot of pure sugar? I don't think so. You know, when my great-great-great-great-great-grandfather went out to kill a cave lion, or whatever they used to do, they would harvest their walnuts, whatever they did. They would bring it back and they would eat a meal. And what happens when you eat a meal is you get a gradual digestion of all of the food. And you don't get like this (exploding sound) sugar bomb. So your body is expecting, when you send sugar down, it's expecting it to be part of a meal. So, here your pancreas is like, "Yeah, just regular old pancreas." And then, one day, you eat a donut. Your blood sugar level goes Boom! Your pancreas doesn't say, "Oh, look, it's a hard candy." Your pancreas says, "My God, this guy just ate the meal of all meals. We better start cooking and putting some glucose away, because we are going to be having glucose for the next two weeks."
And so, here's what happens. So, let's just say, we're moving along here and what do we do? We have our glucose level and here we are, we'll make glucose red. And your glucose level is fairly nice and steady, and then all of a sudden, "baboom" you go ahead and eat this thing. "Bam!" Up goes the glucose level. So, what are you going to do? Well, your pancreas is going along there and it's making enough pancreas, yeah, pancreas is fine, and all of a sudden, the pancreas says "Holy mackerel, Boom. We have to start taking some of this glucose and start putting it away. And so it literally produces enough insulin to put away thirty-seven turkey dinners, if you will, because that's what it's expecting to happen.
So, you're going to get a ton of insulin produced, but guess what? You don't have thirty-seven turkey dinners. You got a little hard candy and a ton sugar. So, very rapidly this thing is going to drop. But it drops so rapidly, that your glucose goes way beyond the time when it peaked and continues to go higher. Well, that's going to cause this to go down and all of a sudden, "Oh man, I don't know why I'm so tired, it couldn't be that donut, could it?" Well, wait a minute, now look what's happening. Now you're way down here and your body is saying, "Get me some sugar" And comes to the rescue, who? Mr. Glucagon. And glucagon comes out and all of a sudden we get to right about here where all of a sudden, we're starting to get low blood sugar and now the glucagon is going to start going up. And the glucagon is going to start going up and so we're going to say, whoa let's start releasing some blood sugar. Boom, and you release blood sugar, and so what is the glucose do? Or the insulin do? Well, obviously, what's the insulin's role? The insulin's role is to take this blood sugar and store it. Well, let's go back to the insulin here. The insulin here was way high. Why? Because our blood sugar was way high. Well, then eventually when this went low, this started to come down, but now this is going up again, so this is going to go up. Can you see what's happening to you? You're going to have this oscillation. Now, eventually, it's going to even out. Eventually it's going to go and get back to that even point where it's supposed to be. Where the idea is that you're supposed to have and this is the whole moral of the story. You're supposed to have an average amount of sugar, which means that you're going to be producing insulin to pull it in and bring it out and pull it in and bring it out. And you're going to be producing glucagon to do just the opposite. But the bottom line is you want an average. And when you popped that baby way high, then you're going to upset your system. So, what's the moral of the story? Save some donuts for me, because I still eat them. I just make sure I'm not going to be teaching just right after I eat them. But there it is. Oscillations. Hormones are never constant. They are always oscillating.
Animal Systems and Homeostasis
The Endocrine System
Endocrine Function: Oscillations in Hormone Levels Page [2 of 2]

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