Lesson video

Hi, I am Mrs. Hutchison, and today I'm really looking forward to teaching you a lesson called insulin and the control of blood glucose level.

This is a biology lesson and it comes under the unit titled, Coordination and Control: Hormones and the Human Endocrine System.

The outcome of today's lesson is, I can describe the role of the hormone insulin in controlling blood sugar levels.

There are some keywords in today's lesson, and they are homeostasis, respiration, insulin, glucose, and glycogen.

So let's have a look in a little bit more detail at what each of those words mean.

So homeostasis is the regulation of internal conditions to maintain optimum conditions for enzyme action and all cell functions.

Respiration is a chemical reaction in living organisms that releases energy from glucose.

Insulin is a hormone secreted by the pancreas when blood glucose level is too high, lowering blood glucose levels, and glucose is a sugar that travels in the blood and is supplied to cells for respiration.

And finally, glycogen is a stored form of glucose found in liver and muscle cells, and we will be hearing those words quite frequently throughout this lesson.

So in today's lesson on insulin and the control of blood sugar level, we will split it into three different parts.

In the first part of the lesson, we're going to be looking at homeostasis and enzymes.

Then we're going to move on to looking at glucose levels and respiration.

And then we will finally finish off the lesson by looking at regulating blood glucose with insulin.

So let's start the lesson with homeostasis and enzymes.

The conditions inside your body are known as the internal environment.

Your organs cannot function properly if conditions keep changing.

Some examples of internal conditions that are controlled are body temperature, water concentration, and blood glucose concentration.

So our body works to keep the internal environments roughly the same.

And three examples of internal conditions that are controlled are body temperature, water concentration and blood glucose concentration.

Conditions inside the body change frequently, for example, due to eating, fasting, and exercise.

There are lots of other examples as well, but those are just three examples.

So looking in more detail during exercise and fasting, blood glucose levels will decrease.

So here we can see an image of some athletes that are partaking an exercise and then an image there showing you some lunch with a cross on, which is showing if you don't eat for a period of time.

So that would be called fasting.

Then both of those activities will decrease the amount of glucose in your blood, and that's because food contains glucose.

And when you exercise, the rate of respiration increases.

So therefore more glucose will be used up in respiration to provide energy for your muscles.

And then after eating or drinking substances that contain sugar or carbohydrates, blood sugar levels will increase.

So we can see there we've got the picture of the packed lunch and there's food in there that contains sugar such as the grapes and also food that contains carbohydrates like the bread and the carbohydrates are broken down into sugar, which is why it will increase your blood glucose levels.

Let's quickly check our understanding of that so far.

So the question is, which two factors cause blood glucose levels to decrease? A, fasting.

B, eating or C, exercising? So this is A fasting and C, exercising.

Eating will generally cause your blood glucose levels to increase.

Looking now at enzymes.

Enzymes are biological catalysts that speed up chemical reactions.

Enzymes control how a cell functions.

The correct functioning of cells is necessary for tissues, organs, and the whole organism to also function properly.

So for a whole organism to function properly, cells need to be functioning and the cell functioning relies on enzymes.

So enzymes are extremely important.

Enzyme function can be affected by the temperature and pH.

Changing temperature or pH can cause enzymes to denature, meaning they can no longer catalyse reactions.

So if an enzyme is exposed to too high temperature or too low temperature, it can mean the enzyme denatures and it no longer functions in the same way that if an enzyme is exposed to too high or too low pHs.

Again, the enzyme can denature and that means that the enzymes can no longer help the cells to function.

Homeostasis is the regulation of internal conditions to maintain optimum conditions for enzyme action and all cell functions.

So we just said in the previous slide that for cells to function properly, it relies upon enzymes.

So therefore our body needs to make sure that the internal conditions are at the best possible levels for enzymes to work at their best.

And this graph here is showing you the action of enzymes.

So we have got the temperature and then the enzyme activity.

And we can see that as you increase the temperature, the enzyme activity increases, and then there's a very quick down slope showing you that once a certain temperature's reached that that enzyme denatures and the enzyme activity will decrease to zero.

And the very peak of that enzyme activity is known as the optimum temperature.

In the same way, the other factor that we said affected enzyme activity was pH.

So this graph is showing you enzyme activity with changing pH.

And we can see again that there's a quick kind of increase in the enzyme activity.

And then very quickly, once the pH goes over a certain amount, then that enzyme activity will decrease again.

And the optimum pH is the point at which the enzyme activity is at the peak.

So let's check our understanding again.

The first question here is, what are biological catalysts called? A, homeostasis.

B, enzymes or C glucose? This is B enzymes.

Well done if you got that right.

Next question, which is the best definition of homeostasis? A regulation of the body so that it works efficiently.

B, regulation of internal conditions for optimum cell functioning or C, keeping conditions inside the body the same.

This is B, so homeostasis is the regulation of internal conditions for optimum cell functioning, and this is because we're creating internal conditions that enzymes are working at their optimum.

We're ready now to move on to task A of this lesson.

In the first part of task A, using the pictures state which three internal conditions the body regulates.

Number two, what might cause a person's blood glucose levels to increase and decrease? And number three, define homeostasis and explain why it is important for the functioning of the human body.

I'm sure you're gonna do a fabulous job.

Pause the video, give it your best go and then press play when you are ready for me to go through the answers.

Let's see how we did.

So the three internal conditions that are regulated are the first one, body temperature, second one, water concentration, and the final picture is showing you blood glucose concentration For number two, what might cause a person's blood glucose levels to increase and decrease? Fasting, which is not eating for a period of time and exercise cause blood glucose levels to decrease and eating or drinking substances that contain sugar, carbohydrates cause blood glucose levels to increase.

Brilliant job if you've got those right.

Well done.

And then moving on to the third question.

So to begin with, we're defining homeostasis and then you need to explain why it is important for the functioning of the human body.

So the definition homeostasis is the regulation of internal conditions to maintain optimum conditions for enzyme action and all cell functions.

And then enzymes are biological catalysts that speed up chemical reactions in the body.

Cells need enzymes to function.

Tissues and organs rely on fully functional cells to keep the whole organism working properly.

Fantastic job if you manage to get that information into your answer.

If you need to pause a video now and use a different coloured pen to correct your answers and maybe add in any extra detail, then I'd recommend doing that.

And we're going to move on then to the second part of today's lesson.

Great job so far.

So we know what homeostasis is and we know about enzymes.

So let's move on now to look at glucose levels and respiration.

Glucose is a sugar that travels in the blood plasma and is delivered to most body cells for aerobic respiration.

Aerobic respiration is a chemical reaction that releases energy and is a vital process that keeps organisms alive.

And then we can see underneath here that we've got the word equation for respiration.

So glucose plus oxygen, they are the reactants for respiration.

And in that chemical reaction, they are converted into carbon dioxide and water.

And as a part of that chemical reaction, energy is released and that energy that's released is then used in lots of other bodily functions, which is what keeps us alive.

So glucose is a very important substance in our body because it is a reactant for respiration, which is what is transferring energy to keep us alive.

Glucose is transported through the body in the blood plasma and is delivered to cells where it is used as a reactant for respiration.

And aerobic respiration occurs in the mitochondria.

So we can see here we've got some images and the first image is showing you a blood vessel.

And the yellow bit on the inside is the blood plasma.

So that's the sort of liquidy part of the blood which transports lots of substances and glucose is transported in the blood plasma.

And we can see the glucose is labelled there as a small green circle.

And that glucose is then delivered to cells, but specifically, it's going to the mitochondria.

So a singular mitochondria is a mitochondrion which we can see here.

And that glucose is delivered for aerobic respiration, which releases energy.

Even when resting, the body requires energy to drive chemical reactions that keep the body alive; glucose is constantly being delivered to cells for respiration.

So here we can see someone sleeping and their body is at rest, but still even at rest the body requires a supply of glucose because respiration is happening all the time in cells to release energy for chemical reactions.

So here the glucose is travelling in the blood plasma again, it's been delivered to the mitochondrion.

And aerobic respiration takes place releasing energy that's needed to drive chemical reactions.

Throughout the day, blood glucose levels rise and fall.

The body constantly monitors the level of blood glucose and will secrete hormones to return the levels to normal.

So we can see here that we've got an infographic which is showing you the changing levels of glucose in the body and between the two lines, that is the ideal range of blood glucose levels.

And we can see that blood glucose increases at times.

So it could be blood glucose is increasing after eating breakfast, but then blood glucose decreases after a period of time of not eating.

And then you'll eat your lunch which causes the blood glucose to increase again, and then it drops back down again and it might go up if you eat something else.

And then you can see at the very end of here, exercising after dinner causes the blood glucose to decrease.

So once again, to reiterate, eating will cause the blood glucose to increase, but periods of time without eating, so fasting and also exercise will cause blood glucose to decrease.

But the key thing to take from this slide is that the body is constantly monitoring the level of blood glucose, whether it's going up or whether it's going, and we want to keep blood glucose levels within this ideal range.

Exercising causes blood glucose levels to decrease because the body has to increase the rate of respiration in order to supply muscles with more energy for contraction.

If respiration rate increases, more glucose will be delivered to cells decreasing blood glucose levels.

So every time you go to do exercise, your muscles need to contract and that muscle contraction requires energy.

That energy is provided through respiration and obviously respiration needs glucose.

So the more energy supplied your muscles, the more glucose is going to be used in respiration.

If you are exercising for a longer period of time, lots of glucose is going to be removed from your blood because it's used in respiration.

The body must monitor and regulate the concentration of glucose within our blood.

And there are symptoms of low blood glucose, which we can see here.

So if your blood glucose levels become too low, you might start sweating.

You have a palate look about you, so you look quite pale, you become irritable hungry, you may start to have a lack of coordination, which is you become a little bit off balance and dizzy and you become tired and sleepy.

And then symptoms of high blood glucose, which would usually present themselves over a longer period of time if you have sustained high blood glucose levels are that you could get a dry mouth, you become thirsty, you become weak, might have more frequent headaches, your vision could be become blurred and you may need to frequently urinate.

If blood glucose levels fall too low, a person could fall into a coma and this can be fatal, which means that it could cause death.

If blood glucose levels remain high over a long period of time, it can cause organs to stop functioning properly, which can also become fatal.

So the key message here is that it is very important for our health for blood glucose levels to be kept within an ideal range, otherwise it can become fatal.

Let's check our understanding of that.

So first question here, glucose is the reactant for which chemical reaction? A, photosynthesis.

B, respiration or C, diffusion.

This is B, respiration.

Photosynthesis produces glucose as a product.

And diffusion is the movement of particles from high to low concentration.

Well done if you got that right.

Next question is true or false? At rest, the body does not need to supply cells with glucose, true or false? Justify your answer.

A, at rest, cells do not respire as the body is not active or B, at rest cells respire to release energy to drive chemical reactions.

So at rest, the body does not need to supply cells if glucose is false.

And the reason is B, because at rest cells respire to release energy to drive chemical reactions.

Even at rest, your body still needs to have metabolic processes that are active and chemical reactions are going on.

Even the beating of your heart requires a supply of energy which will be provided through respiration.

And the next question, which activity causes blood glucose levels to increase? A, exercising.

B, eating or C, fasting? This is B, eating.

Exercising and fasting make blood glucose levels decrease.

Fantastic job if you got those right.

We're ready now to move on to task B of the lesson.

And in the first part of task B, you need to annotate the diagram to show why it is important for glucose to be delivered to cells of the body.

And there are labels on that diagram to help you.

And then for question two, are these statements about glucose levels and respiration correct or incorrect? A, it is not dangerous for blood glucose levels to become too high or too low.

B, glucose is constantly being delivered to cells for respiration and C, during exercise, blood glucose levels increase as respiration rate decreases.

And then for the third part of task B, use the statements you identified as being incorrect in the previous task and write out the correct statement.

So again, give this your best go, I'm sure you're gonna do a fantastic job.

Pause the video and then press play when you're ready for me to go through the answers.

Let's see how we did.

So starting with the first question, we had to label this diagram.

So you've got glucose which travels in the blood plasma and is delivered to cells, and then we've labelled the blood plasma there.

Then you've got the mitochondrion, which is a singular word for mitochondria.

And aerobic respiration occurs in the mitochondria, inside cells releasing energy to drive chemical reactions and muscle contraction.

And then finally that last arrow is showing you that energy is released through the reaction called aerobic respiration.

If you need to pause a video to add anything in, then please do.

For question two, it's not dangerous for blood glucose levels to become too high or too low.

This is incorrect.

B, glucose is constantly being delivered to cells for respiration.

That is correct.

And C, during exercise, blood glucose levels increase as respiration rate decreases.

This is incorrect.

So if the question three, now looking at those two incorrect statements, let's write out the correct version.

So it is very dangerous for blood glucose levels to become too high or too low.

If blood glucose concentration decreases too much, you could fall into a coma and it can be fatal.

If blood glucose concentration is increased for a long period of time, it can cause organs to stop functioning, which can also be fatal.

And then the second incorrect statement, during exercise, blood glucose levels decrease as the respiration rate increases.

The respiration rate increases as muscles need energy to contract.

And this energy is transferred through respiration.

So there was only one word there that was incorrect.

Well done if you spotted that and were able to explain why it was wrong.

Fantastic job so far.

So we know what homeostasis is and enzymes, we now know about glucose levels and how it's linked to respiration.

So let's look now in more detail about regulating blood glucose with insulin.

Can you remember which gland in the endocrine system this is? So there's a line pointing there to a specific gland.

Can you remember what that gland is? It's the pancreas.

Well done if you got that right.

The pancreas is the organ in the body that detects changes in blood glucose concentration.

So we've spoken about the pancreas being a gland and it is a gland because it secretes hormones, but it is also an organ that has other jobs as well.

But the pancreas importantly is the organ in the body that detects changes in blood glucose concentration.

If blood glucose concentration is too high, the pancreas will detect this change and secrete a hormone called insulin.

So if you eat some food and your blood glucose level starts to increase, the pancreas detects this and it secretes the hormone insulin.

Insulin travels in the blood plasma to its target cells in the liver and in the muscles.

So here you've got the pancreas, which is detecting the change.

So if you've eaten something, your blood glucose level has increased and the pancreas secretes insulin, which is the hormone.

It travels in the blood plasma and it gets delivered to the target cells, which in this case are the liver cells and the muscle cells.

Insulin acts on the liver to reduce blood glucose concentration by increasing the amount of glucose absorbed from the blood into the cells.

So remember, the pancreas has detected here that there's too much blood glucose.

So once the insulin has got to the liver and muscle cells, the insulin gets the liver to increase the amount of glucose that it absorbs from the blood and then converting excess glucose into glycogen which is stored in the liver and muscle cells.

So the liver has two jobs here.

It increases the amount of glucose, it's absorbs from the blood into the liver, and then it converts that glucose into something called glycogen which is then stored in the liver.

So if this was the liver here, it absorbs glucose from the blood and then it converts glucose into a substance called glycogen that is stored in liver and muscle cells.

And both of these actions reduce the level of glucose that then is in the blood.

By removing glucose from the blood and converting it into glycogen to be stored, the blood glucose concentration decreases back to normal.

So glucose is being converted into glycogen.

So you've got glucose that's in the blood and it's being converted into glycogen, which is stored in the liver and muscle cells.

And that process decreases blood glucose concentration.

And that's the response that we want from the body because glucose has increased.

So our body responds by decreasing the levels back to within that ideal range.

The pancreas helps to regulate blood glucose levels by detecting increases in blood glucose concentration and then secreting insulin to bring levels back to normal.

So here again, we've got that infographic that we saw earlier where there's variations in blood glucose concentration, but the two lines represent the ideal range of blood glucose levels.

And we can see on these blue lines here, the blood glucose is increasing and as a result, insulin is secreted causing the blood glucose to return back to normal.

So it is normal to have slight variations, but our body works to make sure that in general blood glucose stays within that ideal range and you can see that it goes up, but then insulin secreted to return back to normal.

Let's check our understanding of that.

So which organ is responsible for detecting changes in blood glucose concentration? A, liver.

B, pancreas or C, stomach? This is B the pancreas.

The liver is the target organ where the cells are that the insulin has a response on and the stomach is the organ in which food kind of goes down our oesophagus into the stomach to be churned up.

True or false question now.

Insulin causes blood glucose concentration to decrease true or false? Justify your answer.

A, insulin causes glucose in the blood to be converted into glycogen and stored in the liver, or B, insulin converts glycogen in the liver into glucose in the blood.

So insulin causes blood glucose concentration to decrease.

This is true and the justification is A, insulin causes glucose in the blood to be converted into glycogen and stored in the liver.

Well done if you manage to get that right.

We're ready now to do the final task of our lesson task C.

So in part one, you need to annotate the diagram to show how the pancreas brings about an effect on the liver when blood glucose concentration increases.

In part two, describe how the body decreases blood glucose concentration.

And then for three, for lunch, Jun ate a ham sandwich, a packet of crisps and a banana.

Explain what happens to Jun's blood glucose levels in the two hours after he eats his lunch.

So again, give this your best go.

Try be as detailed in your answers as you possibly can.

Pause the video and press play when you're ready for me to go through the answers.

So let's see how we did with part one.

So the organ that's circled there is the pancreas.

The pancreas secretes insulin, which is a hormone.

The insulin travels in the blood plasma and it targets the liver and muscle cells.

So well done if you manage to label that correctly.

Number two, describe how the body decreases blood glucose concentration.

So insulin acts on the liver to reduce blood glucose concentration by increasing the amount of glucose absorbed from the blood into cells.

And then secondly, converting excess glucose into glycogen which is stored in the liver and muscle cells.

You might have written this in different wording or in a different order, but maybe just pause the video and check you've got everything in that answer that you need before we move on.

And then for number three, so Jun has had his lunch.

Explain what happens to his blood glucose levels in the two hours after he eats it.

So when Jun eats his lunch, his blood glucose levels will increase.

The pancreas will detect the increase in blood glucose concentration and secretes the hormone insulin which travels in the blood.

You might have written blood plasma to the liver and muscle cells.

Insulin causes the cells to absorb more glucose and convert glucose into glycogen, which is stored in the liver and muscle cells.

And then as a result, the blood glucose concentration will decrease back to normal levels.

There's a lot of information in that answer, so I'd recommend pausing the video and making sure you've got everything in there that you need.

A fantastic job if you've managed to do that well.

A really great job, this lesson, well done.

Let's just summarise everything we have learned today.

So we started off the lesson by talking about homeostasis and we said homeostasis is the regulation of internal conditions to maintain optimum conditions for enzyme action and all cell functions.

And as part of that, we said that cells function properly due to enzyme action and if cells function properly, that means that tissues will function properly, organ systems will and the whole organism.

So the whole organism is very reliant on enzyme action and therefore the body needs to keep internal conditions roughly the same so that enzymes function at their very best.

We then spoke about blood glucose concentration and we said that blood glucose concentration is one internal condition that the body regulates as part of homeostasis.

Glucose is a reactant for respiration, so that means it's needed for respiration, and the body needs to carefully regulate the concentration of glucose in the blood.

We also said that even when somebody is at rest, so if they're sleeping, their energy is still being provided to drive chemical reactions, so therefore respiration is taking place at all times.

So glucose needs to be supplied to cells at all times.

The pancreas detects changes in blood glucose concentration and secretes the hormone insulin when glucose levels increase.

We then said that insulin travels in the blood to the liver and muscle cells and causes an increase in absorption of glucose into cells and the conversion of glucose into glycogen that is stored in the liver and muscle cells.

And this causes a decrease in blood glucose levels so that they return back to normal.

Really fantastic job, this lesson well done.

You've done amazing work and look forward to seeing you next time.