Hello, my name is Mr. Wilshire.

And in this lesson, we're going to be looking at the function of blood.

So let's dive in and have a look.

The outcome for this lesson is, I can describe what blood is and what it does.

As always, there are some keywords for our lesson here with some different definitions.

Don't worry if you're not too sure what some of them mean.

The meaning should become clear as we progress through these different slides.

If you need to, you can pause video after this and have a recap of what some of these words are.

The words are blood, function, nutrients, oxygen, and carbon dioxide.

Pauses the video now if you want to have another read.

The first part of this lesson is called the functions of blood.

Now, humans can't live without blood.

We need the blood inside us to keep us alive.

Aisha here says, I know that blood is important to us, but I don't actually know what it does.

Do you? Do you know what blood actually does? Pause the video and have a quick discussion.

Let's think on some more.

Andeep here says, blood has many different functions.

I think it carries important things around the body.

Well, now that we've got Andeep's suggestion as well, do we agree? Is that what you decided in your discussion? Have a quick think.

Did you agree with Andeep? Let's move on and find out more.

When we eat, nutrients from food such as vitamins and proteins are absorbed into our blood through the small intestine.

Here, you can see some different fruits and vegetables, which are really good sources of vitamins.

The function of blood then is to transport all those nutrients and water from food around the body to different places where they are needed.

This helps our body to grow and repair in order to stay healthy and strong.

Let's stop and think quickly.

Blood is needed to do what? Does it act as a pump, does it keep us alive, or does it feed us? Blood here is needed to keep us alive.

When we inhale, air enters our body and then travels down to our lungs.

Here, you can an image of some lungs and the position of those lungs in the body.

Although we take in air containing many gases, our body uses only oxygen.

Oxygen in the air passes from the lungs and into our blood.

The function of blood is to transport oxygen to different parts of our body so that they can keep working.

So we inhale the air into our lungs and then we exhale air that has been used by our body.

So we inhale oxygen and we exhale carbon dioxide.

It's the blood's job, in that case, to take that oxygen to different parts of our body.

So if the heart wasn't beating, then the blood wouldn't be able to move around the body in that way, delivering the very important oxygen.

All different parts of our body need oxygen to move and survive.

Here, you can see that the blood is travelling around the body in different ways.

There are lots of different tubes and lines throughout our body that carry this blood.

So let's stop and think.

Blood transports blank and blank to the different parts of the body so that they can keep working.

What does it transport? Two answers here, oxygen and nutrients.

Blood transports oxygen and nutrients to the different parts of the body so that they can keep on working.

So when blood delivers oxygen to different parts of the body, carbon dioxide is taken away, just as I was saying earlier.

Remember, the lungs exhale carbon dioxide, so our body is generating carbon dioxide as it moves and as it works.

Carbon dioxide is a waste gas that your body does not need.

Aisha says, if we don't need carbon dioxide gas, what do we do with it? Have you been listening so far? Stop and have a think.

What happens to that gas? A function of blood is to carry the carbon dioxide gas back to the lungs where it is then exhaled.

So blood doesn't just carry oxygen to different parts of the body.

It also takes the waste product as well, the carbon dioxide, to be exhaled.

In the lungs, it's removed from the body in the air that we breathe out exhaling.

Have a go exhaling now.

(inhales deeply) Each of those times you've inhaled oxygen and then you've breathed out, exhaled, carbon dioxide.

Now Aisha has fallen over in the park and she's damaged the skin on her leg.

She said, oh, I've cut my leg and blood is leaking out.

Laura says, don't worry, it'll stop bleeding soon.

How? How does our body know how to stop things bleeding? What do you think causes the bleeding to stop? Pause the video here and discuss.

Restart when you've done that.

What did you think? How does the blood stop leaking out of our body? Well, another function of blood is to help humans stop bleeding if they get cut.

Sofia says, oh, yeah, when I scraped my arm, it stopped bleeding and eventually a hard scab appeared.

Now blood will form a scab on the surface of your skin.

This stops us from continuing to bleed if we cut ourselves.

Here, you can see a scab on someone's elbow.

I wonder if you've ever had this happen to you.

I certainly have.

If I've fallen over and scraped the skin, blood can then start coming out.

But after it's been cleaned, it then forms a bit of a scab.

This helps the skin to repair itself as well.

Aisha said, I've heard that when you are unwell, your blood helps you to get better.

Well, yeah, you can see someone who's not very well over there.

So she's right.

Another function of blood is to fight infection.

And this is caused by things like germ, and bacteria, and viruses.

The blood knows how to fight these different things as you grow up.

It's why you might find that you are a little bit poorly as you are younger.

Your body is learning how to fight these different infections.

The heart pumps blood all around the body.

Without blood, oxygen and nutrients wouldn't be able to get to the different parts of the body that need to function.

Carbon dioxide and waste products wouldn't be able to leave the body and they continue to build up.

Your body also wouldn't be able to fight infections.

And you wouldn't be able to form a scab to heal cuts.

So you'll continue bleeding if you fall over and hurt yourself.

That's not very good, is it? So let's stop and think.

What substances move from the body into the blood to be taken away? The answer here is carbon dioxide and other waste materials.

So the body gets rid of the carbon dioxide and the waste materials, sometimes by exhaling it, sometimes in other means.

So here's your first task.

Who do you agree with here and why? Aisha says, the function of blood is to help make you better if you're not well.

Laura says, the function of blood is to stop you bleeding if you're cut.

And Andeep says, the function of blood is to transport different things around the body.

You need to have a discussion and decide, who do you agree with and why do you agree with it? What is it that they're saying that you particularly agree with? Good luck with your task.

Restart the video when you've done that.

How did you get on? Well, all of the children are correct.

Blood helps you to fight infections when you're ill.

Blood will form a scab and heal your cuts.

And blood will deliver oxygen and nutrients to parts of the body that need it.

It then transport the waste things out to be removed from the body.

And that's the air that we breathe out.

Did you find that all of them were correct? What other thoughts have you had about the function of blood? The second part of our lesson is called the parts of blood.

Now, human blood appears to be a red liquid, but it's actually made up of a liquid and solids that are too small to see without a microscope.

Human blood is made up of four different things, plasma, red blood cells, white blood cells, and platelets.

And Andeep here says, each part has a function within blood.

So those four different things, they all do a different type of job.

We can show the different parts of blood in this model diagram here.

Here, you can see a white fluffy thing.

Now that's called a platelet.

This red blob is a red blood cell.

Here, this white blob with different bits inside it is a white blood cell.

And there's lots of orange stuff as well, isn't there? Well, that is the plasma.

If we were to use a microscope to really zoom in to a single drop of blood, this is what we would find.

There are lots of red blood cells, there's orange plasma, there's a few platelets, and a couple of white blood cells as well.

This is the composition of blood.

All of these different parts do different jobs.

So let's stop and think quickly.

Which of these is not a part of the blood? Have a look and read.

What do you think? The answer here is scabs.

A scab is not a part of the blood.

A scab is something that is formed on the skin when you cut yourself.

Now plasma is a yellowish liquid that carries the red blood cells, the white blood cells, and platelets all around your body.

Here, you can see, after an operation, that plasma has been separated from the blood.

Now this can often happen when somebody is donating blood or donating stem cells to somebody to use in a battle against an infection.

Two different bags there are showing how it has been extracted from the blood.

Plasma will also transport water, nutrients, and waste products all around the body.

Aisha says, I wonder why blood is red when it's mostly made from plasma, which is a yellowish liquid.

That's a good point.

I wonder if you've got any ideas here.

Why is blood red? Pause the video and have a discussion.

What did you think? Why is it red? Well, Andeep says, our blood is red because it contains millions of red blood cells and they travel through the body with the help of plasma.

If you use some colouring and mix colours together, usually the more there is of one particular colour will mean that the water will turn that colour regardless of other colours that are there.

Here is a model of some red blood cells.

So in the bloodstream, this is what blood would look like if you were looking through a microscope.

Red blood cells look very similar to a donut but without a hole.

Red blood cells are really important.

They carry oxygen from your lungs to all the parts of the body that need it.

Red blood cells then travel back to the lungs, taking away carbon dioxide to be exhaled from the body.

So the heart pumps the blood to the lungs, it gets oxygen, it pumps it somewhere else to be used up, and then that organ or muscle uses the oxygen but gets rid of carbon dioxide as it uses it.

The red blood cells then travel back towards the heart for it ready to be exhaled and then to be filled up with oxygen again and restarts.

Andeep here says, well, this looks very different to a red blood cell.

Oh, yeah, this is a model of a white blood cell.

Human blood will contain white blood cells, which are responsible for fighting infections.

And this could be caused by different germs, like bacteria and viruses.

So a white blood cell, although there's not as many of them, they're there to help fight the different things that could harm your body.

They help you get better.

These are all things that are happening inside.

And remember, there are lots and lots of these inside one single drop of blood.

Sofia says, when I scraped my arm, it stopped bleeding and eventually a hard scab appeared.

Of course, she said that earlier, didn't she? This little white fluffy thing is a platelet, and it helps to form scabs on the surface of the skin.

This stops us from continuing to bleed if we hurt ourselves.

So we've had plasma, that's the orangy liquid, we've got red blood cells that transport oxygen and gets rid of carbon dioxide, we have white blood cells which help to fight infection, and finally here, we have platelets.

And the platelets are the parts of the blood that helps to repair the body.

So let's stop and think.

Human blood is made up of different parts.

Is this true or false? The answer here is true.

Of course it is.

It's made up of lots of different parts.

But how can we justify our answer here with some scientific thinking? Blood is made up of plasma, red blood cells, white blood cells, and platelets.

The second answer there, you can't see any parts in blood, it's just a red fluid, is wrong.

If we were to use a microscope and really zoom in onto a droplet of blood, we would be able to see some of these different cells as they're divided.

So which part of the blood helps form a scab when we get cut? The answer here is platelets.

Platelets help to form a scab when we get cut.

Andeep, Aisha, and Laura decide to make a model to describe what blood is and its different functions.

Laura here says, well, I'd like to use some apple juice to represent the yellowish plasma.

Oh, that's a good idea.

There's lots of other yellow liquids as well that she could use.

I wonder what else.

Aisha says, models help us to understand things we can't see in real life.

Of course, yeah, we can't see it with the naked eye, but with a microscope, we can.

Andeep says, or we could use some little white pompoms to represent the blood cells.

Oh, of course, yeah.

So all of these things together could make a good model.

So if a scientist or a doctor were to look through a microscope, they would have something to compare against.

So let's stop and think.

Why might you create a model of blood? The answer here is because you can't see the separate parts of blood without a microscope.

It is nice to be able to look at models, and blood can be interesting to look at, but they aren't very scientific answers, are they? So this moves us on to the final parts in our lesson about the parts of blood.

You need to plan a model to describe what blood is and its different functions.

You need to use Aisha and Andeep's ideas or you can use some of your own.

Aisha here says, well, we've got some water, yellow food dye, and raisins.

These could be the plasma and the platelets maybe.

Andeep says, we've also got some cereal hoops, and some red food dye, oh, and mini marshmallows.

They could be the white and the red blood cells.

Well, that's what the children are going to be doing.

I wonder how you are going to make your model.

Are there some different items that you could use to represent blood and create your own model? Have a think.

You also need to draw a diagram of what each part represents in your model.

So then have a go at making it.

Best of luck with that task.

Restart the video when you've done that.

So your task was to plan your own representation of blood.

Your ideas may have been similar to this.

Here, you can see a model of blood that the children made.

Andeep says, we created our own model of blood using different items. Raisins were similar to platelets.

We used some cereal hoops and some red food dye to create the red blood cells.

Their circular shape was perfect.

Remember though, the red blood cells that we saw underneath a microscope didn't have a hole in.

Sophia says, well, plasma was recreated by using some vegetable oil because it's a yellow liquid.

And Aisha says, the small marshmallows were great to use for the white blood cells because they're white and fluffy.

Maybe your model was similar to this or maybe you had a different composition.

Remember, the majority of blood is made up of red blood cells, isn't it? So hopefully you used a lot of those items just to make sure that your model is accurate.

So let's summarise our lesson.

Blood is needed by humans to keep them alive.

Blood transports oxygen and nutrients to all the different parts of the body so they can keep working.

Blood transports carbon dioxide and other waste materials to be removed from the body.

And blood is made of different parts.

Each part has a different function within blood.

A model can also be used to describe what blood is and its different functions.

Maybe, in the future, you're going to use some of this knowledge to help you become some sort of research expert into blood.

Lots of people need replacement blood sometimes, maybe because they've lost it or maybe because there's been an infection in their blood and they need it to be replaced.

There are some amazing operations that can go ahead in hospital to replace the blood in somebody's body, which is amazing, isn't it? That is literally a lifesaving thing to do.

Whatever you decide to do or go ahead and research in the future, the best of luck to you.

I've been Mr. Wilshire.

Thank you very much for listening.