Lesson video

Hello and welcome to today's lesson.

My name is Mr. Swayze and I'm really looking forward to teaching you today.

We are going to be looking at pulling together all of your understanding about the cardiovascular and about respiratory systems to consider how they work together to provide energy for exercise.

Today's lesson is a practical exploration of how the cardio-respiratory system work together, and it comes from the Anatomy and Physiology, the Cardio-Respiratory System unit.

By the end of this lesson, you'll be able to explain how the cardiovascular and respiratory systems work together to support performance in sport.

So this is your chance to really remember all the names, the functions, and all of the different parts of the respiratory tract and the chambers of the heart, and which blood vessels carry blood to wear around the body before creating a walkthrough replica to help you remember that passage of oxygen from the atmosphere to the muscle site, and then the passage of carbon dioxide from the muscle site, outta the body.

We will also be bringing in that knowledge of lactic acids and the impact of the intensity of exercise on lactic acid production to try and tie all of this together to really understand what's going on in our bodies when we start to exercise.

The key words for today's lesson are cardio-respiratory, gaseous exchange, and performance.

We'll give you a chance during the lesson to explore these definitions, but maybe you want to pause the video now to make a note of them.

The important one around gaseous or gaseous exchange, and also sometimes you'll come across it known as just gas exchange, and sometimes used interchangeably with the term diffusion because gaseous exchange, gaseous exchange, gas exchange and diffusion, they're all about that process of oxygen and carbon dioxide being switched between the lungs and the bloodstream or the muscles and the bloodstream.

Okay, so this lesson's split up into two parts.

The first part will really get you capturing your knowledge around that pathway of oxygen into and the pathway of carbon dioxide out of the body, before the second part digs a bit deeper into the impact of gaseous exchange on performance.

So let's get started.

Okay, as we've explored before, air containing oxygen is breathed in (inhales), and it comes in from the atmosphere and travels the respiratory tract to the alveoli in the lungs.

Oxygen from that air then diffuses from the alveoli into the bloodstream where it binds with haemoglobin to form oxyhemoglobin before being transported around the circulatory system back to the heart and then from the heart out to the working muscles.

And I guess if you're exercising with your arms, it will go predominantly to your arms, and if you are perhaps riding a bike or running, it would go predominantly to your leg muscles, or maybe you're playing a sport that requires your arms and your legs, so there'll be a fairly equal distribution of blood to your arms and to your legs.

And then at those working muscles, the carbon dioxide is exchanged for oxygen and we need to take that carbon dioxide back out of the body and that comes first via the heart, and then on up to the lungs, and then we exhale a higher proportion of carbon dioxide in air than what we breathed in.

So let's have a quick check.

True or false, muscles produce oxygen as a byproduct of respiration.

That's right, it's false, do you know why? Okay, so oxygen is used to produce energy for muscular contractions, whereas carbon dioxide is that byproduct produced during respiration that must be expelled or got rid of from the body.

So we can see here in this nice little animation that oxygen is coming into the body, circulating around the different blood vessels to the muscles, and then carbon dioxide is following a pathway back to the heart and then back out of the body.

But can you remember all of the names of that pathway of oxygen to the lungs? Hopefully you remember that it comes in through the nose and mouth, down through the trachea, splits off into the bronchi, then into the bronchioles, and eventually ends up at the alveoli.

So the oxygen will be coming in that way, and then back out again as carbon oxide.

Let's do another quick check.

So which of the following describes the correct pathway of air from the atmosphere to the alveoli? Is it A, the nose or mouth into the trachea, into the bronchioles, into the bronchi, then to the alveoli, or is it B, the alveoli to the trachea to the bronchi to the nose and mouth, or is it C, the nose and mouth to the trachea, to the bronchi, to the bronchioles, and then finally the alveoli? Give you a moment to decide.

Well done, of course it's C.

The bronchi break off into bronchioles, whereas A, we got those the wrong way round, didn't we? Okay, so if we have another little look here, this is what's going on at the alveoli.

So the oxygen is coming in to that alveoli, that sac, air sac in the lungs, and it's diffusioned out into the blood capillaries and being carried as oxygenated blood around the body.

And as Aisha says, you know, look at that, that's diffusion in action.

And then maybe we could pull onto the other side because at the same moment, it's carbon dioxide that's diffusing out again.

So we've got both of these processes happening at the same time all of the time in our lungs.

And if we start to exercise, the process just happens faster.

Oxygen is coming in and carbon dioxide is coming out of the blood vessels.

So that brings us nicely to our first task, task A.

And what I would like you to do is grab a whole load of, you could use post-it notes, you could use a sheet of paper and cut it up into sections, but basically I want you to come up with a whole load of labels that have got those key anatomical features that go from the atmosphere all the way to the working muscles, and then that go from the working muscles all the way back out to the atmosphere.

So it'd be all of the key words for the respiratory tract and the different chambers of the heart and the different blood vessels around the body.

And then for each of those labels, the second thing I'd like you to do is write a quick description of the location of it.

So where is it in the body and what is it that happens at that thing, that feature? And then thirdly, I'd like you to indicate on your labels whether it is carrying oxygenated blood or deoxygenated blood that is full of carbon dioxide.

So the smartest way to do that is to perhaps colour them in red if they're carrying oxygenated blood and colour them in blue if it is deoxygenated blood that's loaded with carbon dioxide.

And then lastly, I want you to lay out those labels in order so that you'll be able to talk out loud that process of air containing oxygen coming into the body in through the lungs, passing through to the bloodstream and the blood and how that goes around the double circulatory system.

So a big task, this one, pulling all of that knowledge together.

So pause the video now whilst you get on with that task, and then come back to me when you are ready.

Okay, so here are a few examples of what should be on your list.

So you can see there, these are all examples of oxygenated blood.

So it comes in, oh, sorry, carrying oxygen.

So not necessarily oxygenated blood because here at the beginning, we're in the respiratory tract, aren't we? So it's oxygen in the air, it's coming in from the atmosphere and it exists in the atmosphere as a mixture of gases.

And then when we breathe it in, we breathe it in through the nose and mouth.

And when it's breathed in, it comes in through the nose and mouth, which warm and moisten that air, goes on down the trachea.

And as it travels down that trachea or windpipe towards the lungs, it'll branch off into the left and right bronchi, one goes into each lung, still oxygenated or air, rich in oxygen here.

Then those bronchi break off even further into lots of bronchioles, so those subdivisions of the bronchi.

And then to the alveoli, which are those oxygen-rich air sacs at the end.

And they come into contact with the bloodstream and the capillary network, which as we know is only one cell thick.

And then we enter from the respiratory system into the cardiovascular system, and this is where that haemoglobin in the blood will pick up the oxygen molecules, grab hold of it via that process of gaseous exchange.

And it's the pulmonary vein that will carry that blood back to the left hand side of the heart.

It enters through the left atrium, that top left chamber, on down through the valve into the left ventricle, then out from the left ventricle into the aorta, and from the aorta, it splits off into the different arteries that supply blood around the body.

And then you should be able to think about how that then enters the capillaries and starts to work its way back through the veins, into the vena cava, into the right side of your blood, so that carbon dioxide filled blood will then get pumped out in the pulmonary artery to go back to the lungs.

And at the lungs it'll be diffusing back out into the alveoli, travelling up the bronchioles, to the bronchi, up through the trachea, out through the nose and mouth, and that carbon dioxide rich air will then reenter the atmosphere.

So well done with that one, a really tough task pulling all of that together.

And when it gets around to your exam, you'll really need to separate out, is the question asking you about the cardiovascular system or is it asking you about the respiratory system? Okay, so moving on to the second part of this lesson that delves a little deeper into gaseous or gases or even just gas exchange and what impact that has on performance.

So gases, then they move from high concentration or high pressure to a lower concentration or pressure via a process known as diffusion.

So we can see there, the molecules that are in orange and the molecules that are in blue, they're spreading across that diffusion gradient to a point where there's an equal number of them on both sides.

And that pressure's been equalised.

Now I think of this a bit like the pressure in a tyre.

So you've got blown up the tyre, it's full of pressure, and then if you've got a puncture, the air comes out of your tyre until that pressure is equalised between what's in the tyre and what's outside of the tyre, so in the atmosphere, which in that instance is actually pretty soft.

And then we would obviously fix the puncture and then we can pump more air back in because it's a sealed unit.

But it's just that knowledge that you know, if you were to have any sort of gases, they like to be at an equal pressure.

So the real nice thing about the capillaries is they enable that movement of gases across them until there's an equal concentration of oxygen in the blood to what's in the alveoli.

And then that helps that extra oxygen to move around to the muscles.

And obviously if you're doing some exercise, your muscles will be depleted of oxygen, so the oxygen will rush in to fill that muscle up with oxygen.

But meanwhile, in that muscle site, it's been producing carbon dioxide through aerobic respiration.

So because there's a really high concentration of carbon dioxide, it's like, oh, I'll filter out into the blood where there's a lower concentration, and then make my way back to the heart, then on up to the lungs.

And again, that higher concentration of carbon dioxide will then come out of the body.

So, "When we start to exercise, what do you think happens to oxygen and carbon dioxide supplies in the body?" And also, "What if you started to exercise at a higher intensity?" Well, exercise results in the depletion of oxygen stores in the body and an increase in carbon dioxide produced at the muscles.

So as a consequence of that, there's that faster diffusion of oxygen into the bloodstream.

Our body's crying out, it's craving, it wants more oxygen, so it sucks more oxygen in much faster via that diffusion into the bloodstream.

And meanwhile, that kind of increased release of oxygen from the bloodstream into the working muscles mean that our muscles can continue to work, but in working they'll produce lots of carbon dioxide.

So that carbon dioxide, where there's lots in the muscles, will want to diffuse out into the bloodstream and then circulate its way back to the heart, back to the lungs.

And then at your blood returning to the heart, it's so full of carbon dioxide, the alveoli go, "Oh, I'll grab hold of that to equalise the concentration or the pressure." And then that enables you to breathe out more carbon dioxide than you breathed in.

Let's do a quick check.

True or false, oxygen travels to the muscles faster during exercise, what do you think? That's right, it's true, and do you know why? Yeah, so when we start to exercise, our automatic nervous system informs our brain of which body parts need more oxygen, and this triggers the cardiovascular and the respiratory muscles to respond accordingly.

So Sam's wondering, "What happens to cardiac and respiratory rates and volumes when we start to exercise?" What do you think? Well, as the demand for exercise increases, we breathe more often, so we have an increased breathing rate.

We also breathe deeper so that tidal volume increases.

And it does that because we're able to reduce the inspiratory reserve volume and the expiratory reserve volume.

So there we've got ourselves breathing more regularly and deeper.

And as a consequence of that, there is a big increase, or therefore there is a big increase in minute ventilation, the amount of air that we get into our lungs per minute, which means that we can extract more oxygen from that air and replace it with more carbon dioxide that's been being produced in our body and expel that out.

So that's what's happening in the respiratory system.

And then meanwhile, with the cardiovascular system, we've had an increasing heart rate.

If we start to exercise and the harder we exercise, the higher our heart rate goes up until of course, that maximum heart rate of 220 beats per minute minus your age.

We've also got a more forceful heart.

We can feel it beating in our chest.

And that's known as our stroke volume, isn't it? So the amount of blood pumped out of the heart per beat.

And then if we multiply those two things together, we end up with cardiac output.

So the amount of blood pumped out of the heart or pumped out of the left ventricle, in fact per minute.

And the same as with minute ventilation, those three dots represent therefore.

So a big increase in cardiac output.

Let's do a quick check.

Which of the following is incorrect? Is it A, excise increases oxygen demands at the muscle, is it B, high intensity excise increases lactic acid production, is it C, low intensity excise increases lactic acid production, or is it D, exercise increases carbon dioxide production at the muscles? Remember, you're looking for the incorrect answer.

That's right, it's C.

As we know, low intensity exercise does not produce lactic acid.

We're able to work aerobically using lots of oxygen and no waste byproducts produced if we're at low intensity.

However, Sam's wondering, "What if your cardiac and respiratory volumes can't increase enough to cope with the demands of exercise?" And Alex wonders, you know, "Do you mean if you're sprinting rather than running?" And yes, that's exactly what I mean.

So what happens if you are sprinting rather than jogging? Well, if exercise is at a very high intensity, then there's insufficient oxygen supplied to the muscles for aerobic respiration to take place.

Consequently, anaerobic respiration happens instead.

And when this happens, there's a partial breakdown of glucose and a byproduct of lactic acid that is produced.

That lactate accumulates in the blood, and once it meets a certain threshold of quantity, it's actually for most people around four millimoles per litre, you don't need to remember that, but once that lactate threshold gets met, fatigue starts to occur.

So that's when we feel like we can't carry on, and we are faced with having to slow down or stopping exercise completely.

So that brings us nicely into the second task that I've got to you for today.

So can you create a physical representation of the pathway of oxygen right from the atmosphere through to the muscles and then carbon dioxide back out of the body? And in doing so, I'm wondering if you can also represent lactic acid production depending on how intensely that exercise is? So some of the sort of equipment that you might want to use, you could use a hula hoop to represent the nose and mouth, you could perhaps have a bench that would represent the trachea, and then maybe four mats that are the four chambers of the heart, skipping ropes to represent the different blood vessels around the body, red and blue cones or red and blue items of clothing to represent oxygen and carbon dioxide, and there may be some yellow items, you know, for example, a yellow water bottle or a number of yellow items that represent lactic acid.

And I want you to lay them all out and then find a way that you can kind of walk through that and talk out loud.

It's a really good way of connecting the left and right sides of the brain so that you can remember those things.

So you're gonna talk out loud of that process of oxygen coming into the body, getting circulated to the muscles, going into the muscles.

Then depending on how hard you are working, are you producing lactic acid or not? Or maybe a little bit of lactic acid.

And then what's happening with carbon dioxide as that gets carried back out of the body? So here's my little drawing that might be similar to what you came up with.

So you can see there the pathway of oxygen into the body through the nose and mouth, down through the trachea, down through the bronchi, through the bronchioles, to the alveoli where it comes into contact with the bloodstream.

So this is the point at which we cross over from the respiratory system to the cardiovascular system.

And then we've got that pulmonary vein carrying oxygenated blood back to the heart.

It goes into the top left, down into the left ventricle, out through the aorta to the working muscles.

And if I was just doing some gentle star jumps, I could keep doing that all day, so I'm not gonna produce any lactic acid, but maybe if I started to do them faster, or maybe I changed from doing star jumps to doing burpees, and they are a much higher intensity, aren't they? So as a consequence, I'm not getting enough oxygen in, so I'll produce some lactic acid.

And when I'm producing lactic acid, that has a fatiguing impact on my body.

So perhaps if I started try to do those burpees for maybe more than a minute, I'm gonna really start to feel that fatigue and have to stop or massively slow down.

So remember, that very high intensity exercise triggers the formation of lactic acid.

Well done with that one today.

A little bit of a different lesson that got you to kind of work through some of these things as a practical experiment, if you like.

So let's summarise what we've learned today about the cardio-respiratory systems and how they work together.

So staying alive requires oxygen, and then if we want to exercise, we will need even more oxygen to come into the body and we get oxygen in via gaseous exchange, and that's when oxygen and carbon dioxide move or diffuse from a higher concentration or higher pressure to a lower concentration or pressure.

The respiratory system gets oxygen into the body, and then the circulatory system transports that oxygen to the working muscles where it gets used through aerobic respiration, or if we're working at too high an intensity, and often this happens when we want to perform really well in sport, we are working at a higher intensity, so some lactic acid gets produced as well, which can be a fatiguing byproduct.

But even if we're working at a lower intensity, we really need efficient respiratory and cardiovascular systems so that we can keep performing at our best.

Thanks for joining me for this lesson today, and I really look forward to seeing you again soon.

See you next time.