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Hi guys. So welcome to part two. for those of you who were here yesterday for part one. Hopefully that went well and today is just gonna be quite similar to that. Um I'm a, I'm a third year medic and I am the crash course lead for today. Um Raman will be doing our first serve of lectures and we've got two more lecturers doing the rest of our lectures today. If you've got any questions at all, just drop it in the chat box. I'm gonna um send all of our emails as well in case you wanna get in touch and ask any other questions. Um and today's session will be recorded and we will upload the slide so you can see everything after as well in case you miss anything. Um But yeah, I'll just let ra and get on with it and that should be fine. Yeah, cool. Um So can you hear me? Ok. Yep, I can hear you good. Ok. Um Yeah, so, hi, I'm Roman. I'm also a third year and today I'm gonna be talking you through two of your lectures, uh exercise capacity and pulmonary function tests. So these are two pretty, they're pretty short lectures, they're pretty straightforward. So I'm just gonna focus on like the main high you concepts within them and it should only take about 30 minutes from my end. So these are the Tylers I've taken from Sophia that are basically being covered by these two lectures and this is the lecture timeline. So I'm gonna start off with exercise capacity and talk through the kind of the only kind of real difficult concept to grasp which I think is ventilation and perfusion. Then I'm gonna move on to talking about the actual tests themselves. And then for your pulmonary function lecture, I'll start by talking a bit about the difference between the types of lung disease and then I'll start focusing on the actual tests themselves. So starting with exercise capacity. So this was the this was taken from your slides. I don't. So this is about ventilation perfusion. I don't think it does a great job of kind of like making it easy to understand. So I just made it a bit more simple. So ventilation, simple, simple, sorry, symbolized by V is basically the flow of air into and out of the alveoli, which is as you know the site of gas exchange. Um and perfusion is sy symbolized by Q and it's the flow of blood to the actual alveolar capillaries. So ventilation, you can think of it, you think of ventilation, you think of it air and then perfusion you're thinking of blood, that's the kind of main er difference. But you need to remember between the two and the apex of the lung, which is right at the top of the lung that receives less ventilation and less perfusion, both at rest and during exercise and the base of the lung receives more ventilation and more perfusion, both at rest and at exercise. So the, these are basically the four kind of key facts you have to remember. So this is again, taken from your slides, just showing the difference between the ventilation and perfusion relationship. Uh depending on the area of the lung we're talking about. So the V over Q uh on the Y axis is the VQ ratio. So this is how ventilation is matched with perfusion. Uh your lung is doing this all the time to be able to provide your body with the oxygen it needs. So at the base of the lung, you've got lot, you've got higher ventilation and high perfusion. And you can see that it matches on the graph. But the main key point here is that at rest, the difference in perfusion between the base and the apex of the lung is more important. It is more significant than the difference in ventilation. So basically what this is saying is that at rest perfusion is the most important factor that determines the VQ ratio. So because of that, if you think about V over Q is a fraction if the perfusion is really high at the base and it's a lot higher compared to the apex, the denominator of that fraction is gonna be larger. So the overall VQ number will be smaller. So because of that, we get a very small VQ ratio at the base of the lung and then that goes um like a curve like that growth, that red curve, it goes all the way up uh when we're talking about the apex and this is just another way of thinking about it. So the apex of the lung, if you can look at the kind of orangey bubble things, um the ventilation is lower. Yeah, and the apex but the perfusion is a lot lower. So because of that, the overall VQ number is higher and for the base of the lung ventilation is higher. Sure, but the perfusion is a lot higher. So that means that overall the fraction is smaller. So the VQ ratio is smaller. So during exercise, the situation changes a little bit. So perfusion everywhere in the lungs, both at the apex and in the base is all increased because think about it during exercise, your body is gonna be needing all of the oxygen it can get. So it needs a lot more blood there for a lot more gas exchange. So if perfusion is increased in the lung everywhere, the difference in perfusion between the different lung zones suddenly becomes not as uh significant compared to when it was at rest. So if you look at the left, you can see the kind of size of the.