bio2 week 2c part 1

eating an oreo..

blood glucose

blood glucose is important

need glucose to make atp

glucose is important for metabolism

too little glucose can reduce muscular or cognitive function

too much sugar often result in type II diabetes

blood glucose is hormonally regulated

homeostasis

negative feedback systems with homeostasis

systems: (hormones blue arrows)

receptors recieve information -there will always be something whose job it is to monitor what's going on in the body

receptors report informationa nd send it to control center

control center: information is processed and orders are sent

control center is USUALLY in the brain

controls centers DONT change environment

effectors: the organ that actually changes the variable

control center -> effector organ -> (response as arrow) physiological variable -> (stimulus) receptor -> control center

hormones are just messengers and never actually affect anything

HOME TEMP EXAMPLE receptors: thermometor control center: thermostat EFFECTOR ORGAN: AC or Furnace TEMP DROPS: physiological variable

when blood sugar is too high, we see insulin, and too low, glucagon

liver, pancreas, hormones and receptors

blood sugar low- > hypoglycemia

hypothalamus: receptor (in the middle of brain and reports functions, monitors blood calcium, body temp, and blood sugar)

for blood sugar regulation, control center is actually pancreas

PANCREASE: CONTROL CENTER --> (glucagon)

LIVER: EFFECTOR (breaks down glycogen) (glucagon tells liver cells to do this)

glycogen is a big complex sugar aka polymer of glucose

releases glucose back into blood

RESPONSE: glycogen turned glucose sends it into blood

for too much sugar, cycle starts with same rceptor and control center, but instead of releasing glucagon, it releases insulin

insulin is a peptide hormone, so its a polar hormone and hits insulin receptors

EFFECTORS can be liver (creates glycogen muscle and adipose (fat) or cells to take up glucose from blood (effectors) glucose is drawn out of blood

EFFECTOR 2: liver

blood sugar bank: takes glucose in to store and rerelease glucose into blood by having a reversible reaction to glycogen

hyperglycemic: insulin travels to liver

blood glucose is stored as glycogen glycogen = polysaccharide - glucose storage molecule

hypoglycemic: glycagon travels to liver where glycogen turns to blood glucose

most cells when taking glucose turn it to cellulose respiration

a lot of similar sounding words so REMEMBER THEM!!

glucagon- hormone glycogen- sugar storage molecule glucose- monomer GLUT transporter: transmembrane protein

bio2 week 2c part 1

Transcript

Just as a rem. Digestion in my mouth, where I'm also adding saliva, which contains amylase.

So amylase, as an enzyme, starts to dissolve the starch that I imagine is in the cookies.

And then after I chew it and I swallow it, it goes through my esophagus and enters my stomach, where there will be more kind of mechanical digestion, but also chemical digestion through things like stomach acids.

Some different enzymes that are going to enter at that point, too, to continue chemical digestion.

Al What I would suggest is, like, doing this every once in a while to, like, pick up on all the little details that kind of string together over the course of the next week we're gonna be tacking on to this story.

So what we're gonna do today is figure out what the endocrine response to that elevated glucose is gonna be.

So if I just ate a whole stack of Oreos, I have a lot of glucose in my blood.

We're gonna figure out how glucoregulation, how.

Insulin actually triggers cells to allow glucose in.

So we're going to keep building on this one story.

So in terms of glucose regulation, so this is kind of what we're talking about today.

We're going to learn about how our body manages to keep our blood glucose levels somewhat stable.

So we know that after we eat, our glucose levels spike.

We're going to need to bring those back down. And then there are also times where after a little while, after it's a long afternoon and we have eaten anything, our blood sugar can drop, which is also not great.

So we know that in general, blood glucose is important.

It's important because glucose is necessary in all cells in order to make ATP.

So we need cellular respiration, we need glucose to make ATP.

So some amount of blood glucose should always be there.

If we start getting blood glucose, that's when we start to feel, like, tired and lethargic and weak, but also kind of mentally slowing down.

All those can be signs that there's not enough blood glucose.

So we definitely need some. But if you have too much too often, that can at least predispose you to type 2 diabetes.

We'll talk more about, like, predisposing factors and things like that.

But it's not good to have really high levels of glucose all the time.

This whole system is going to be hormonally regulated.

So we're going to talk today about the hormones involved in this process of keeping blood glucose levels pretty constant.

So really, I just want to show you this so you can read the cartoon.

But we're going to look at homeostasis today. So we've talked about different kinds of homeostasis before.

This is no different than a lot of those. When we talked about homeostasis and other kinds of regulation, we talked about thermoregulation, we talked about osmoregulation.

In all of those cases, there's this, like, the same patterns that exist with glucose regulation, where we have glucose levels that are too high and then we bring them back down, and then glucose levels go too low and we bring them back up.

What kind of system are we describing here? Negative feedback. Yeah. So same thing here. We're going to be talking about negative feedbacks, same as in all of these other examples of different kinds of regulation.

They all. All these homeostatic systems basically just involve negative feedback systems.

So when we looked at thermoregulation a while back, we know that there are kind of different sets of responses that our body will have, whether we're too hot or too cold.

The same thing Is going to be true for glucose levels.

If our glucose levels are too high, A different set of systems are going to kick in, A different set of hormones, A different set of factors Than if our glucose levels are too low.

But before we talk about specifics, I want to step back and think about some of the pieces of these homeostatic systems.

Whenever we're trying to monitor internal conditions and adjust, There are a set of roles that we can assign to different things that are kind of constant throughout.

So these homeostatic systems, One thing that is necessary Is for there to be a receptor.

So receptors, in this case, are the part of a system that monitors the environment.

All they do is receive information. So there will always be something whose job it is, is just to monitor what's going on in our body.

That's called the receptor. Those receptors, all they can do is collect information and report it to the control center.

So the control center is where information from the receptors are received.

That information is processed, and then kind of orders or instructions are sent out to other parts of our bodies under almost all circumstances except glucoregulation.

The control center is in the brain. It's some part of the brain for glucoregulation.

It's actually somewhere very unusual. We'll talk about that in a minute. But the control center is where information is gathered and orders are set down.

But the control center can't actually change the environment.

The thing that changes the environment is called the effector.

So if we're thinking about. If we're thinking about thermoregulation, what's an example of an effector?

What's something that actually changes our body temperature?

Yeah, sweat. Cleanse. Yeah. Sweat glands would be an example of the effector.

Right. So that's the thing that, like, releases water that evaporates and cools us down.

So those would be the effectors. Does anyone know what the effector would be for osmoregulation?

We didn't talk a lot about human osmoregulation, but it's basically like blood concentration and water.

It could not quite dilute blood vessels. Has a lot to do with blood pressure. Yeah. Kidneys. Yeah, via kidneys. Right. So we were like, get rid of water in our blood through our kidneys.

That's not important. But what we're going to talk about today is like this system, but for glucose regulation.

One other thing to note that's up here Is that hormones themselves, like we talked about what hormones are, we talked about the endocrine system before.

Hormones never occupy any of these Roles. They cannot be the control center. They cannot be the effector. All they are are the messengers between those different parts.

So they're all the blue arrows on here. Those are hormones. All right, so let's go through a quick analogy for this just to get you an idea of how this might work.

And I want to think about it like the temperature in your apartment.

So in the temperature in your apartment, what is the thing that just collects information about the temperature?

What would that be? What is the thing that all it can do is collect information on temperature?

It would have to be a thermometer. We don't often think about there being thermometers in our houses because they're housed within something else.

But it's the thermometer in that other thing that does its only job is to collect temperature.

So we have thermometers as the receptors. And then what is going to be the control center then?

Yeah, that's the thermostat. The thermostat receives information from this thermometer constantly.

So it's taking information, and that's the thing that decides what to do.

So if the temperature comes back and it is too warm, it's like 84 degrees inside your house.

What is the control center then going to do with that information?

Tell it to turn it down. Turn it up. Ac. It's going to turn on the AC unit. Right. The thermostat itself can't change the temperature.

Right. So the thermostat itself has no ability to do that, but it can send a message to the AC unit that it should turn on and it should change the temperature.

So the AC unit is the effector. The thermostat is the control center. The thermometer is the receptor. Okay. So hopefully that, like, when you think about these things, Think back to this example.

I find this is actually super helpful. All right, so we're gonna move on to glucose regulation, But I want to see what you know first.

So take a second to, like, take stock of all the things you think are part of the system.

What are the hormones involved? What are the organs involved? How do you think they're related? Take a minute, talk to the person next to you. See how much you can figure out hormones. You got your brain pushing out hormones. I think she just means the organs in the digestive process.

I say with hormones, wouldn't that be stuff like control center?

Could be brain. What would it be for glucose production? Like kidneys? Yeah, well, either kidneys or liver. Or pancreas. Pancreas. The hormones would come From, I think, a pancreatic cell into the blood.

Because that was a part of the questions on the weekly quiz last week.

Okay. Receptor. All right, so what's something that you've identified that is part of the system?

What's. What's something we know? Blood. Good. Blood. What is blood gonna do? What's its role here? Transport. It's gonna transport glucose. But also what hormones? What are some hormones? We got what, insulin. Yes, insulin. Right. So insulin is part of the system. So insulin is. Do we have insulin when our blood sugar is too high or too low?

Too high, yeah. So we're gonna see insulin come around when our blood sugar is too high.

What's the hormone that's gonna show up when our blood sugar's too low?

Glucagon. Very good. Glucagon. We'll talk about glucagon. Where are those things made? Does anybody know? The pancreas? Yep. So it's made in the pancreas. Any other parts that we think are important here?

The liver is important. We're going to talk about the liver, too. Okay, you got the major players. Now let's see how they're related. So basically, I'm going to draw this, like, big figure 8 diagram that talks about what we're going to do when our blood sugar is too low and then what we do when our blood sugar is too high.

Kind of like that little diagram of the little guy that was, like, shivering and then swimming.

So in this system, we're going to start off with normal levels of blood sugar, but let's say it's been a few hours since we've eaten, and our blood sugar drops below the threshold of four parts per million.

And what do we call it when our blood sugar is low? Hypoglycemia. Hypoglycemia. Right. So if we're hypoglycemic, hypo is low. So in a hypoglycemic condition, the receptor, the thing that is monitoring blood sugar all the time is our hypothalamus.

So the hypothalamus is a part of our. We're not going to do a lot with, like, brain anatomy, but the hypothalamus is in the middle of your brain, and it has a lot of reporting functions.

So not only does it kind of monitor blood sugar, it also monitors body temperature, blood calcium levels, a whole bunch of different things.

So the hypothalamus is going to be our receptor. Normally, the control center would also be right next to it in the brain.

But in the case of glucose regulation, the control center is actually your pancreas.

So in your pancreas, it's receiving information from the hypothalamus, because that's all it can do, receive information, and then it's deciding what to do.

So if the report to the pancreas is 4 parts per million or less than 4 parts per million, then the pancreas is going to start to produce a messenger called glucagon.

So a hormone called glucagon gets produced by the pancreas.

When we're hypoglycemic, that hormone enters the bloodstream because there's no other way for it to move around.

And the other thing to remember about hormones in the blood is you can't target blood to go to a specific place.

So when hormones enter the bloodstream, they just go everywhere that blood goes.

So as glucagon is flying around our system, in our blood, it's got to wait until it basically bumps into receptors.

And the receptors for glucagon are found in the liver.

So when glucagon binds to liver cells, we'll talk about what exactly this means in a second.

But it's going to tell those liver cells to break down something called glycogen.

I mentioned glycogen once in class. Glycogen is a big complex sugar, so it's basically a polymer of glucose.

So stick a whole bunch of glucose together, that's glycogen.

So glucagon comes, binds the liver cells, breaks apart glycogen and releases glucose into the blood.

So the liver puts glucose into the blood. Even though we haven't eaten anything, we can elevate our blood glucose levels back to normal or into the normal range, and then we're back to homeostasis.

So this is like the hypoglycemic loop. Let's see what happens on the other side. So now, instead of it being a while since we ate, we just ate one of the.

Or we just had one of those. Like, what is it? This Starbucks Frappuccinos. That's worth, like, 17 scoops of ice cream. So if we just had a Frappuccino, our blood glucose level spikes were above this, like, threshold of 6 parts per million.

And just like before, the hypothalamus is the thing that's monitoring our blood sugar.

That's all it can do. Taking in that information, sending it to the control center, which is still the pancreas.

And then the pancreas takes that information. But this time, instead of releasing glucagon what's it going to make?

Insulin. Insulin is produced. Does anyone remember? You might not. What kind of hormone? There are three kinds of hormones, right? What kind of hormone is insulin? The big peptide one. Yeah. So it's a protein or a peptide hormone. So does that mean it's polar or non polar? Polar. Polar. So it's got insulin, this big polar molecule being produced, put into the bloodstream.

It's traveling around, it doesn't need a carrier protein because it's already polar, it can dissolve.

So insulin is now flying around inside our bloodstream and it's going to hit receptors for insulin.

But there are lots of places where there are receptors for insulin.

So there's actually two kind of categories of effectors here.

One is again the liver. So the liver is going to do something specific when it binds to insulin and then we have all these other cells like muscle cells and fat cells and basically most other cells also have insulin insulin receptors.

Are they going to be intracellular or extracellular extra?

Right. Because they're polar molecules, they're going to bind on the outside of the.

Alright, so insulin is traveling around, it binds to receptors in the liver and then all over places.

But basically what it's going to do is take, it's going to signal to those cells to bring the glucose that's in the bloodstream into the cells, basically lowering blood glucose by moving all of that glucose into cells.

What happens to that glucose in the cells differs a little bit and we'll go over that.

All right, so this is the main diagram that we're going to be kind of working off of.

But I want to put some information together in different ways.

So let's think specifically for a second about the control center, the pancreas.

So in the pancreas, again, depending on the report from the hypothalamus, if we have high blood glucose, it's going to make insulin and that insulin is going to attach to all these different effectors, the liver cells, fat cells, muscle cells, all these different places with insulin.

We'll talk about what happens there in a second. But if the report from the hypothalamus is hypoglycemic, then instead when the glucose is too low, glucagon is released and it goes through the liver.

Let's talk about the liver. In the liver this says effector2. I'll go back and talk about effector2 in a second.

So in the liver, basically the, the way we should think about the liver in glucose regulation is that it's basically A blood sugar bank.

What I mean by that is when there's excess blood glucose, it's going to take it in and store it.

And then when we don't have enough, it can break apart and re release glucose into the blood.

And it does that by converting glucose back and forth, glycogen.

So when we have a lot of glucose, the liver is going to store it as glycogen.

And when we don't have enough blood glucose, it's going to break apart this polymer and release the glucose back into the blood.

So this way it's like a bang. So if we are hyperglycemic, we have a lot of blood sugar.

When insulin binds, sugar enters and is stored as glycogen.

And when we're hypoglycemic, if there's not food on the horizon, which would be another way to raise your blood sugar.

But if there's not food and we're hypoglycemic, glucagon can bind to liver cells.

And the instructions there are break apart all that glycogen that we made last time we had too much glucose and kind of time, release it back out into our blood.

So that's the liver's role in this process. There's one other effector here which is basically like most of the other cells in our body.

And most of the other cells in our body, instead of taking glucose in to store it for later, what are they going to do with it?

Most cells, as they take in glucose, are going to do what, cellular respiration?

Yeah, cellular respiration. They're going to turn it into ATP. So that's what we're doing here. So in muscle cells and other body cells other than the liver, insulin triggers those cells to take in glucose in a process we'll talk a lot about for the purpose of respiration.

So all this glucose entering all these other cells is going to get burned up and used as ATP.

Any questions so far? I think one last thing I want to say about these two places, these two effectors, is that the amount of sugar that goes into each is not even right.

It's kind of proportional to the number of cells that they represent.

The amount of glucose entering the liver is much smaller than the amount of glucose going into all of our other cells.

So while they're both like, they're both contributing to the drop in blood glucose levels, it's not equal.

So one last thing is that a lot of the words I said today sound really similar, and I don't have a good way for you to memorize what's what.

You're just going to have to try to figure it out. I really don't. Glucagon is the hormone. Glycogen is the sugar storage molecule. Glucose is the monomer. And then next time, we're going to talk about something called a glut transporter.

Okay? Just how it goes when you're talking about sugar.

All right, that is it. I will see you.

Made With Glean | Open Event