Lesson video

Hi there.

Welcome to your lesson.

Today's lesson is on the air pathway from the atmosphere to alveoli and gaseous exchange.

My name's Miss Hacking, and I'm really looking forward to being your teacher today.

By the end of today's lesson, I'm hoping that we can all describe the pathway of air from the atmosphere through to gaseous exchange in the lungs.

Today's keywords include trachea, bronchi, alveoli, gaseous exchange, and diffusion.

You may wish to pause the video now in order to take a note of all the keyword definitions, but we will be talking about them in a bit more detail in today's lesson.

So today's lesson is split into three different learning cycles.

In the first part of today's lesson, we're going to identify the pathway of air.

In the second part of today's lesson, we're going to describe the process of gaseous exchange.

I wonder if you already know anything about gaseous exchange and what gases might be involved.

And for the third part of today's lesson, we're going to describe how exercise affects gaseous exchange.

But you may already know this because you will have done a lot of exercise and a lot of physical activity in your PE lessons already.

So you might already be able to think about what happens to the gases you take in and the gases that leave your body.

Let's get started.

So the respiratory system brings air in and out of the body.

So it does this by inhaling, bringing air into the body, and exhaling, getting rid of waste products from the body.

Air that we inhale contains a lot of oxygen that we need to help the body function properly, and we particularly need it in sport to go to our working muscles.

When we exhale, we exhale waste products like carbon dioxide.

We get rid of those.

We want to get rid of those from the body so we're able to function properly and not have a buildup of waste products.

I wonder if you can already identify any parts of the respiratory system.

You may have learned these in science, but remember, it's a part of the body to do with breathing air in and breathing air out.

You may wish to pause the video while you have a go at labelling as many parts of the respiratory system as you can.

Here are all the labels of the respiratory system.

Well done if you've got any of those correct, but we're going to be talking about them in a little bit more detail now, so don't worry if you forgot some of them.

So first of all, the lungs are protected by the ribcage, or the ribs.

So you might remember talking about these when we talked about the skeletal system.

So the ribs surround our chest cavity and they protect our lungs from getting damaged.

For example, if we were playing sports and we didn't have a ribcage and a ball hit our lungs, it could cause some serious damage.

Whereas now because we have the ribs there to protect them, if a ball hits us, as long as it's not too hard, it doesn't really cause that much damage.

In between each of the ribs is a thin sheet of muscle called the intercostal muscles.

Now, some people don't really associate the muscular system with the respiratory system, but the intercostal muscles are really important in helping us to breathe, because when we inhale, our chest cavity gets bigger, so our lungs expand to get more air into our body.

Now without the intercostal muscles, our ribcage would be fixed and we wouldn't be able to move it out when we breathe in, so we wouldn't be able to get more air into our lungs.

So the intercostal muscles, when we inhale, move the ribs out, and when we exhale, bring the ribs back in.

We also have another sheet of muscle called the diaphragm that runs below the lungs.

The diaphragm contracts as we inhale to get in more air to the lungs.

When we exhale, the diaphragm turns into a dome under our lungs to push out any extra air back in into the atmosphere.

Air enters and leaves the body via the nose and mouth.

I'm sure you already knew that.

Sometimes a nose can be called the nasal cavity.

When air has entered our body through the nose or the mouth, it then goes down our trachea to the lungs.

The trachea is also known as the windpipe, and it goes down our throat all the way to our lungs.

Right, let's have a go at a check.

Can you fill in the missing labels, label one and label two? Yes.

Well done if you put nose or nasal cavity for number one, and well done if you remembered the trachea for number two.

Remember, trachea is one of our keywords today, so well done if you got that right.

The bronchi are two tubes that branch off the trachea into each lung.

Air travels through the left and right bronchus.

So the bronchi is a name for the plural, whereas a bronchus is the individual tube.

So if I'm saying the left bronchus or the right bronchus, it's a bronchus, but if there's two of them, they're bronchi.

Air then travels through the bronchioles, which are small tubes that branch out from the bronchi.

So they're like little twigs that are coming off sort of the two tree branches, the bronchi, the tree branches.

The bronchioles are the twigs at the end of the branches.

Okay, let's have a go at another check.

Can you fill in the missing word? Yes, well done.

It's the bronchioles.

Double check that you got that spelt correctly, bronchioles.

From the bronchioles, air travels into the alveoli.

Now, the alveoli are tiny air sacks where gaseous exchange happens.

Air travelling to the alveoli diffuses across the alveoli walls into the blood capillaries.

This is where the respiratory system and the cardiovascular system link together in order to get the oxygen in through the body and around the body to where it is needed to function properly, but particularly in sport, to get delivered to the working muscles so that they don't fatigue.

So the structure of the alveoli enables efficient gaseous exchange to occur.

This is because they have very tiny air sacks and they have very thin walls, which means that oxygen can diffuse across from the alveoli into the blood capillaries.

And it also means that waste products like carbon dioxide can diffuse from the blood capillaries back into the alveoli to come back through our respiratory system to be breathed out.

That is why gaseous exchange is so efficient at the alveoli and blood capillaries.

The alveoli are surrounded by lots and lots of blood capillaries, which means that more gaseous exchange can occur.

It makes it more efficient and effective to get oxygen into the body where it's needed and carbon dioxide out of the body where it's not needed.

They also have a large surface area, which allows more gaseous exchange to take place, which is why the alveoli enables such efficient gaseous exchange.

So let's have a go at a check.

Can you tell me which two body systems work together at the alveoli? Yes, you are right.

It's the respiratory system and the cardiovascular system.

Well done for getting that correct.

Here you can see how the oxygen travels from the atmosphere through our nasal cavity or mouth, down our trachea into our lungs, through our bronchi, bronchioles, alveoli, where gaseous exchange would happen with the cardiovascular system.

Let's have a go at a check.

Which of the following is the best description of the function of the respiratory system? Is it A, this system pumps blood around the body? Is it B, this system helps you breathe in and out? Or is it C, this system is made up of all the bones in the body? Which do you think best describes the function of the respiratory system? Yep, that's right.

This system helps you breathe in and out.

We inhale air in through our respiratory system and we exhale air out through our respiratory system.

Well done if you've got that correct.

So now it's your turn to have a go at a practise task.

The first part of the task, I'd like you to add labels to identify the correct components of the respiratory system.

And for the second part of the task, I'd like you to fill in the missing words to show the pathway of air from the atmosphere to gaseous exchange, starting with the nose and the mouth of how the air enters the body.

For the third part, you can use your flowchart to help you with this.

Can you describe the pathway of air from the atmosphere to gaseous exchange in the lungs using full sentences? You may wish to pause the video now so that you've got time to complete the tasks.

Good luck.

Okay, let's see how you got on with the tasks.

How many labels did you get correct? So air enters the body through the nose, or nasal cavity, or the mouth.

Well done if you've got those two correct.

Air then travels down the trachea towards our lungs.

At the lungs, it will split into the bronchi.

Now you may have put right or left bronchus here, and that's okay too.

From the bronchi, it travels to the bronchioles and eventually ends up at the alveoli where gaseous exchange occurs.

Give yourself a tick for every one you got right.

Well done if you got them all correct.

For the second part of the task, you were asked to fill in the missing words to show the pathway of air from the atmosphere to gaseous exchange, and the nose and mouth was given for you.

Then it moves to the trachea, down to the bronchi, into the bronchioles and to the alveoli.

Well done if you've got the order correct.

So then using your flowchart, you should now be able to describe the pathway of air from the atmosphere to gaseous exchange in the lungs using full sentences.

You may have written something along these lines.

Air enters the body at the mouth or nose.

It travels down the trachea to the lungs.

At the lungs, the air moves through the bronchi.

The air then travels through the bronchioles to the alveoli.

The alveoli is where gaseous exchange takes place.

And you may be able to even talk further and talk about how gaseous exchange occurs at the alveoli between the alveoli, the respiratory system, and the capillaries of the cardiovascular system in order to get blood around our body so our body can function and also our working muscles can use the oxygen without getting tired.

Well done if you got that correct.

Okay, let's move on to the second part of today's lesson, describe the process of gaseous exchange.

So gaseous exchange means that gases swap over a surface.

Just like the diagram you can see, the gas particles move from one side of a surface to the other side of a surface.

Which gases do you think get exchanged at the alveoli? We've already talked about them a little bit in today's lesson, but I wonder if you can remember what they are.

The gases exchanged at the alveoli are oxygen and carbon dioxide.

Oxygen diffuses from the alveoli into the blood capillaries, and carbon dioxide diffuses from the capillaries into the alveoli.

So we want to get oxygen into our body, into the blood, to be transported around the body to our working muscles, to our organs.

But we also want to get rid of the waste products like carbon dioxide out of our body.

So it diffuses from the blood into our respiratory system where it moves back up our respiratory system and into the atmosphere when we breathe out.

So diffusion is where gases move from a higher concentration to a lower concentration.

Here we have an image where there's a high concentration of gas particles in the circle and a low concentration of gas particles outside of the circle.

So what will happen is the gas particles will diffuse through the circle into the atmosphere where there are a lower concentration of gas particles.

Now this will happen until the concentrations remain equal.

When they remain equal, then diffusion will stop.

But if there is a higher concentration and a lower concentration, the higher concentration will move to a lower concentration.

So let's have a go at a check, shall we? True or false? Gas diffuses from low concentration to high concentration.

That's false.

Can you tell me why? Hopefully you've written something along these lines, that gas always diffuses from an area of high concentration to an area of low concentration.

It never goes from an area of low concentration to an area of high concentration, always high to low.

Don't get those muddled.

So when you breathe in, the alveoli has a higher concentration of oxygen than the blood.

As you can see on the diagram, someone has just breathed in and their alveoli is full of oxygen.

Therefore, the oxygen diffuses from the alveoli into the blood capillary.

This happens because there is a low concentration of oxygen in the blood capillary.

So therefore, oxygen moves from the high concentration in the alveoli to the low concentration in the blood capillary.

The blood capillary therefore will then take oxygenated blood around the body.

Okay, let's have a go at a check.

When we breathe in, oxygen diffuses from high concentration in the blank to lower concentration in the blank.

Can you fill in the blanks for me please? I hope you got that when we breathe in, oxygen diffuses from higher concentration in the alveoli to lower concentration in the blood capillary.

Well done if you got that correct.

So the oxygen combines with haemoglobin in the red blood cells to create oxyhemoglobin.

The blood then takes it to where it is needed in the body.

Oxygenated blood delivers oxygen and collects carbon dioxide, and deoxygenated blood returns to the heart and is then pumped to the lungs.

So the blood takes the oxyhemoglobin to where it is needed in the body.

So when we are particularly doing exercise, the oxyhemoglobin is needed at our working muscles.

So if I'm doing something like bicep curls, for example, and I'm doing lots of them, I need the oxyhemoglobin to get transported to my biceps and triceps that are working really hard.

Without the oxyhemoglobin, my muscles would get very tired very quickly.

So it's important that our respiratory system and our cardiovascular system work together in order to get oxygen to where it is needed in the body.

Oxygen diffuses from the alveoli into the blood capillaries and therefore travels around the body in the arteries via the heart, because the heart pumps the blood around the body.

When it gets to the working muscles, the oxygen will diffuse to the working muscles and the blood will pick up the carbon dioxide.

When the blood's picked up the carbon dioxide, it'll be known as deoxygenated blood.

It will travel back to the heart where it will then be pumped back up to the lungs so that gaseous exchange can occur and the carbon dioxide can diffuse back into the lungs, into the alveoli, and therefore be breathed out.

Okay, with the help of a practical example, describe where oxygen will be required.

Let's have a go together first.

So when performing a squat, oxygen will be required at the gluteals, the quadriceps, and the hamstrings, as these are the working muscles.

Let's see if you can have a go and complete the sentence below.

When performing a bicep curl, oxygen will be required at the blank and blank as these are the working muscles.

Can you fill in the blanks? Yes, I'm hoping that you've put: when performing a bicep curl, oxygen will be required at the biceps and triceps as these are the working muscles.

Now, can you create your own example? You may wish to pause the video in order to give yourself time to write them down.

Okay, now, we might not be able to give individual feedback to everyone because you've all probably written different examples maybe to do with your favourite sport.

But well done if you put something along these lines and correctly identified the working muscles from your example.

When performing 100 metre sprint in athletics, oxygen will be required at the quadriceps, the hamstrings, the gluteals, and the gastrocnemius.

Now let's hope that you put the working muscles that are relevant to your examples like I did with the 100 metre sprint.

I picked the working muscles, which were the quadriceps, the hamstrings, the gluteals, and the gastrocnemius.

So I hope you did the same.

Well done if you did.

So when you breathe out, the blood has a higher concentration of carbon dioxide than the alveoli.

That's why it's deoxygenated blood, because there's no oxygen in there.

There's just carbon dioxide.

Therefore, from the blood, the carbon dioxide will diffuse back into the alveoli because there'll be a higher concentration of carbon dioxide in the blood capillary.

Therefore, the carbon dioxide will move from the high concentration in the blood to the low concentration in the alveoli, where it'll then travel up through our bronchioles, into our bronchi, up our trachea, and out through our nose or mouth.

Okay, let's have a go at a check.

True or false? Carbon dioxide moves from high concentration in the alveoli to low concentration in the blood capillary.

Yes, that's false.

Can you tell me why? Okay, I'm hoping that you noticed the obvious mistake.

Carbon dioxide moves from high concentration, but not in the alveoli.

It moves from high concentration in the blood capillary to low concentration in the alveoli.

So this example was wrong because it had confused the alveoli and the blood capillary.

Okay, now it's your turn for practise.

The first thing I'd like you to do is label the key parts of gaseous exchange at the alveoli.

You may wish to talk to me about the type of blood that is passing and which parts are also labelled on A, B, C, and D.

For the second part of the task, I'd like you to describe the process of gaseous exchange by completing the sentence starters below.

You may wish to pause the video now so that you're able to see the sentence starters to help you write up the sentences.

Good luck.

Okay, I'm hoping you got the correct labels.

So A was the blood capillary, and B was the oxygenated blood.

C was the alveoli, and D was the deoxygenated blood.

We often draw oxygenated blood as red and deoxygenated blood as blue to help us know which type of blood it is.

Task two, describe the process of gaseous exchange by completing the sentences.

I'm hoping that you've got something along these lines.

When you breathe in, the alveoli has a higher concentration of oxygen than the blood.

The oxygen diffuses from the alveoli to the blood capillary.

Oxygen combines with haemoglobin in the red blood cells to create oxyhemoglobin.

During exercise, oxygen is needed in the working muscles.

When you breathe out, the blood has a higher concentration of carbon dioxide than the alveoli.

Therefore, the carbon dioxide diffuses from the blood into the alveoli.

Well done if you put something along those lines.

You may have even given me some examples of working muscles for a particular physical activity.

Well done if you did that too.

For the last part of today's lesson, we're gonna describe how exercise affects gaseous exchange.

This might be something you are already familiar with or you might be able to have a guess at from your own experience of practical sport.

So gas exchange varies with the intensity of exercise.

Intensity means how hard you do it.

So going for a walk would be quite low, steady intensity, whereas sprinting as fast as you can would be really high, hard, tough intensity.

So have a think.

What happens to your breathing when you exercise? So when you exercise, breathing rate, which means how fast you breathe, increases.

For example, if we just run 100 metre sprint, you'll probably notice that your breathing has got a lot faster straight after you finish that 100 metre sprint.

But equally, breathing depth increases.

So not only how fast you breathe, but how much air you take in.

And again, if we go back to the 100 metre sprint, you often see people on the finish line, after they've run as fast as they can, taking in big, deep breaths in order to replace any oxygen that they have used while exercising and to aid their recovery.

So during aerobic activity, breathing rate increases.

So aerobic activity is activity that uses oxygen that is normally done at quite low to medium intensity, and it's done at low or medium intensity because it's done for a long period of time.

So aerobic activity is an endurance activity, something like long distance cycling, for example.

Therefore, there is an increase in gaseous exchange to get more oxygen to your working muscles.

So because breathing rate increases, gaseous exchange happens quicker because it needs more oxygen to get into the body, to the working muscles, so that the muscles don't fatigue because they are exercising for a long period of time.

After anaerobic activity, breathing rate and depth increases, which means you breathe often and deeper.

And again, the 100 metre sprint is our example of anaerobic activity.

Anaerobic activity doesn't use oxygen at the time, and it's normally a short activity, but it's high intensity.

So the 100 metre sprint is a very short activity, but you do it as fast as possible at your maximum intensity, but as soon as you finish it, you will need to breathe more often and breathe deeper in order to get all that oxygen back into your body to replace any that you've lost and to help with recovery.

Therefore, as a result, there is an increase in gaseous exchange because you are getting more oxygen into your body.

Gaseous exchange needs to happen faster so that we can get more oxygen to your working muscles to aid recovery.

Let's have a go at a check.

True or false? The rate of gaseous exchange increases during exercise.

Yeah, that's true.

Can you tell me why? Gaseous exchange does increase during exercise to meet the increasing demands of oxygen from the working muscles.

Our working muscles are working harder, therefore they need more oxygen.

They work harder when we exercise, whether that's aerobically or anaerobically.

They're working harder, so gaseous exchange happens quicker, it increases.

Okay, using one of the practical examples below, describe how exercise affects gaseous exchange.

Now it's your turn to have a go.

So you can either use a marathon runner or 100 metre sprinter to describe how exercise affects gaseous exchange.

You can pick which example you'd like to use.

You may wish to pause the video now so that you have time to write your answer.

Good luck.

Okay, so using one of the practical examples below, describe how exercise affects gaseous exchange.

So if you picked the marathon runner, perhaps you wrote something along these lines.

During a marathon, a runner will require more oxygen at their working muscles.

Therefore, they will breathe faster and deeper to get more oxygen into their body.

As a result, gaseous exchange at the alveoli will increase to allow the marathon runner to get enough oxygen to their working muscles.

Well done if you wrote an answer similar to that, but as long as you put that gaseous exchange at the alveoli increases, you are on the right lines.

And if you selected the 100 metre sprinter, you may have written something like this.

After completing 100 metre sprint, the athlete will breathe faster and deeper to replace the oxygen used by the body when sprinting.

As a result, gaseous exchange will increase to aid recovery and to replace the oxygen used when sprinting.

Again, well done if you've talked about the fact that gaseous exchange has increased to replace any of the oxygen lost in order to support recovery.

I think we're on the right lines.

Well done.

Okay, that just leaves us a little bit of time to summarise today's lesson.

So the respiratory system is made up of tissues and organs that help the body to breathe in and breathe out.

Air enters through the mouth or nose.

It travels down the trachea, into the bronchi, through the bronchioles to the alveoli where gaseous exchange happens.

Gaseous exchange is the process of diffusion where oxygen moves into the body and carbon dioxide moves out of the body.

Diffusion is the movement of particles, for example, oxygen or carbon dioxide, that move from an area of high concentration to an area of low concentration.

It's always high concentration to low concentration, never the other way around.

Gaseous exchange increases during or immediately after exercise because we want to replace the oxygen or we want to support the muscles in using more oxygen.

Well done today.

You've worked really hard on quite a tricky topic, so I hope you found it useful.

I'll see you again soon.