Planetary Physiology
Summary
This engaging teaching session focuses on the fundamental theme of Planetary Health and Sustainability in the medical curriculum. Throughout the course of the session, participants will utilize interactive quizzes that challenge their knowledge and pique their curiosity. The lecturer, a co-author of the book "Sustainable Health Care," guides participants through topics like living systems, planetary physiology, feedback systems, and even the Gaia organism. This session aids the students in their future endeavors as they potentially lead and navigate the NHS (National Health Service) through significant changes in the 21st century.
Learning objectives
- Understand and identify the relationship between planetary health and sustainability, and the impact of this on future healthcare systems.
- Explore the concept of planetary physiology and its parallels to human physiological systems such as the gastrointestinal system.
- Gain knowledge and understanding of systems theory within the context of planetary health and sustainability.
- Learn about the Gaia organism and the concept of planetary boundaries, and how these can influence healthcare systems.
- Develop a better understanding of how the NHS contributes to and mitigates climate change and other environmental issues.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.
Wh all so, yeah, that makes OK. And that awesome. Right. Keep the, do I see, you know? Yeah, I, I take, yes, I know. I, that was crazy. Yeah. One so good morning, everybody. Let's uh let's make a start. Ok. So th th this lecture, er, it forms part of one of the, your curriculum's heal themes called planetary health and sustainability. And the reason I guess that it exists is that you guys are gonna be leading the NHS through its transition to, through the interesting things that are gonna happen over the course of the rest of this century. And in this actual lecture we're going to be looking at living systems to come in. Oh, look, late arrivals. Hello. You're welcome. So, it's a, it's a kind of unusual idea. We're gonna be studying planetary physiology just in a remarkably similar way to the way in which you're going to study gastrointestinal physiology at I think 11 o'clock today. And then in year two, there's a lecture which looks at the pathology, which is the theme of the year two curriculum in general. And in year three, we look at how the NHS contributes to and mitigates the, the sorts of things we're gonna be talking about. So as you can see these three lectures follow the structure of your curriculum as a whole. And I have been working and researching this area for quite a long time. I'm the, the coauthor of this book, Sustainable Health Care uh by B MJ books. This is the title, this is the cover for the book that we suggested that they have. Uh Does anyone want to shout out where this picture is from Easter Island? OK. And uh there's a reason why we chose that as our possible title. And if you're interested in collapsing civilizations, then there's a no better book to read than this one. I can see the the meter logos covering the author Jared um Jared somebody. OK. So that's good. Now, um I was just curious just to get the um mental ball rolling just about the level of concern that you personally feel for planetary issues. Cars. OK. So good. Just hold, hold that information if you would in your mind. Uh Now I've never tried this before. I'm going to next level mental use in this lecture, right? And what we're gonna do, I thought, you know, the normal thing is to provide somebody with some material and then run a quiz on it. Um We're gonna do the opposite. We're gonna have the quiz first. OK? Before we've had any material and also just from the laws this is a competitive quiz. So when you, when you get to the next slide, you will be asked to put in your name. Now, you can put in your actual name or you can put in a synonym or a fun name, but it's probably better not to use the name that someone else might have. So if you're using a pseudonym, don't use, say Peter or Ahmed or something common, right? So then you won't be able to know who's who. So let's just see what the hell happens here. OK. So you should be able, it's interesting already. Is it working? B oh That's a shame. Um So when you go into ment meter that doesn't appear anyone got it working. No, I suspect there will be a fix. Ok? If I got the wrong code, for instance, can't be totally wrong. 81. Can you bear with me? As I said, I've never done this before. Uh Let's go back a slide. So that one was fine, right? And then as I set it up, when you get to this one, you should be being asked to enter your details. I'm just getting, you didn't vote in time on mine. Oh, this is sad. Let's try the next one just in case it's ok. What I'm gonna do? I'm not gonna, I don't gonna give up too easy on this. I'm going to reset the quiz. Anyone know how to do that. Manage results. That looks good. Now try, huh? Ok. So let's try. No. Ok. Now you should get, the quiz should not appear. Did you get to vote? Yes. Ok. Oh, I love your iphones guys. The faster you answer the more points you get. C ok. Keep going. Don't give up centralized decentralized or distributed. Yeah. Don't give up. Now, there's eight questions. All right. I'll give you a clue. Two of these are correct, but I think you can only vote for one of the two. OK. Now, I think the next slide is quite interesting. Oh, yes. The reason you got, you get extra points for how quickly you answer. OK. So let's see whether we can top big bars in the Norwegian. Let's go to the nearest 100. I believe you should know this fact. I'm disappointed if you don't. I did say the, the rules include not looking things up on the, on the internet, by the way, folks. OK. Let's see. OK. OK. That's that, that this is basic planetary physiology. OK? That if you got that wrong, it's a bit like saying the duodenum comes before the stomach as you as you'll probably know it doesn't. Right. This is a text answer. You have to answer it. A exactly spell it. Right. We're giving you extra time for this one. Yeah. Five questions. All right. That's an interesting answer today. OK. Demeter. Interesting. I think that might also be correct, but too bad. Is it? It's not a fair, fair world. Oh, on that? Fantastic. Good on fella and Bobby leading away though. Ok, you ask. Ok, this one is the decider, like if you get this, um, ok, you are allowed to cheat on this one. I'll, I'll see if you can look it up fastly. Yeah. And I've even allowed a couple of different spellings just to be nice to you. Well, I treatment or either beb blast, you try. It'd be interesting to know where, what Vin blasting comes from. Maybe it does. Did anyone find that? Oh, sorry, your life's not fair. Oh, Bella, did she hold on to her, Bella held onto her lead. Nice work, Bella. But uh pretty, pretty clustered at the top there. That's good to see. So that is an unusual way to do the quiz, but it gives you a sense of the territory that we're about to go into. Um, here II always puts that stupid little warning thing up. Um These are the, these are the learning outcomes for the lectures. These will be the things that will be examined. The sorts of questions you'll get will be the sorts of questions you've just been asked. Um And uh yeah, why not? Because this is, this is important material as you'll hopefully soon learn. And do I need to say more about uh OK, learning my way here, folks. He cannot advance in the normal fashion to his lives. So we're going to study systems theory, we're going to look more at feedback systems. We're going to look at the planetary level, the so called Gaia organism. And we're going to be looking at concepts of planetary boundaries and latitude and a little bit more about where we're going with this over the course of the curriculum. If you don't understand any of the learning outcomes at the moment, that's absolutely fine. That's what the lecturer is here to do is to teach you something that you don't currently know. Um So it's a talk about systems and uh what systems are? Something that we medics are really quite familiar with. Do you want? Could you name your system? Sorry. And it just, ok, I'll accept that as I was thinking more since this is a physiology, your all say end system, correct. You know, you know what I'm getting at here, we are used to that terminology. However, as far as I know, I'm the only person who will teach you about systems. In other words, systems in general, not a specific system like your 11 block lecture on the gastro gastrointestinal system. So I thought we just, I just nip back to ment. I, what I would like is a one sentence definition of a system. Uh Let's see if this works. It does amazing. OK, so it's just a one, a brief definition of the word system. See what you come up with. OK. Good. I'm liking what I'm hearing. I don't know how to scroll down. I haven't tried that yet, but I think I probably could. Ok. So the, the sorts of things I'm picking up is there are things so there are bits and the bits are connected together. They work together potentially in a network and potentially for a common goal. Like for instance, digesting our food. That would be an example of it, wouldn't it? So, um, very good. Let me just get to my notes. So there's no, let's see what happens when I go here. Hi. So yeah, ni like it, it's going well. Um this is just the oe one actually, it's not a particularly good one but put it up. Um So what you've already told me is that you understand that net that systems are generally composed of parts that work together and that is um really fine when the parts are obvious. So for instance, my hand that I'm using at the gesture is clearly attached to my forearm, to my upper arm, to my shoulder and so on to my will, to my intention. Um But in fact, there are many, many aspects of systems that are not visible and in medicine, for instance, um human emotion is an example of a human system that's easily ignored within a consultation because it's, you have to ask about it. It may not be obvious people are very good at hiding how they feel. Um And I thought I'd just do a little experiment to um test this. And so my, my um request to you is to draw a tree. Just that's why I said you don't get a paper anymore, do you? OK. Right. This is time for honesty. I want you to draw the tree in your imagination, please. If you've not or you've got a sketch pad, just draw down three for a minute. OK. I wanna see that tree. Yeah. OK. You too. So my question is, there's a, people are sketching on the computers can be used for drawing by the look of it. OK. So your tree, the one in your imagination or the one that you're just drawing or trying to draw before I sort of interrupt with, you didn't have a funny developed root system or not. OK. So just, just fess up to your ruthlessness. So when it comes to trees really, you do, if you want to understand a system called a tree, you need to understand its roots. And this is true of um all plants and it's also true metaphorically. Would you remind me of human beings? So a tree without roots is clearly not a tree, it's not a full tree. And that's what I meant by the fact that parts are so easily ignored. Um Hopefully, it's amazing it's working. Um So this is the quiz question. So you can see that a l in terms of biomass, which is, if you shake out all the dirt and just weigh the damn thing. Um Grassland is like two thirds under the ground and anyone who does allotment like I do, we know this, the roots, the massive for grasses and they take a lot of digging out trees, not so much, but still a lot. And that, that, that's the general point I make. Ok. Great. Ok. So, um we've talked, we're talking about systems in general. We've agreed that they have parts, we've agreed that some of the parts are invisible and that invisibility is quite important in medicine. We also did look at, I think in one of my lectures last time about what happens when you connect simple bits of a system. So we're talking about now, not so much the parts but how the parts connect to each other. And do you remember we had these very simple system that's about as simple as you can get, it just carries on until it stops. OK. But if you put two of these in series, then it starts to behave in a way that is literally. So that's another feature of systems which is that the parts interact in a way that allows see that novel things to emerge, agree. You know, we don't know that. Now, I just thought that we might try to do an experiment with the whole group to see whether we can, we can prove this point in another way. And I have to admit I've never done this before. Mm. It's not what I expected, let's see. Yes. OK. So, two network experiments. So, what I want you to do everybody's attention back row the whole lot, full attention here. I want you to, I want you to find somebody in the election theater who you're going to focus your attention on. Um, so just one person just pick somebody at London and keep them in view. That's all you have to do. And, um, when that person that you're looking at stands up, you so simple as that, that's so simple. Uh Yes, sir. I know I've been to you before. Do you mind standing up for information? Doesn't always hurt, say something, not at the very back. Would you be surprised to stand up? The stomach? Take two guns when the person that you're looking at stands up, you stand up, you, so do you mind standing up? Ok. Ok. Ok. You, you can stand up. Oh, ok. Keep it, keep it, keep your eyes peeled on your person. That's interesting. It stopped. Ok. You sir. Would you mind something up? Oh, but he, ok, let's, let's not stop. Keep, uh, keep your eyes peeled. You must stand up if your person stands up. Are you sure about? Yes. So, yeah, yeah. Ok. Sit down there. Really? Right. I've done that. What I haven't done the sport but what I expected to happen was that I would pick one person and then slowly more people would stand up and then everybody could stand up. Uh And the, and if it work as well as I expect and I worked, it does depend on a few variables that we can sort of work out mathematically what would happen there. But the general plan is that a very simple rule. When the person that you're looking at stands up, you stand up and a very simple intervention you stand up can create a very major effect in the system. So that's a bit like the, like a form the patterns. I suspect it by following relatively simple rules in a network. So let, let's maybe, maybe we, maybe this is hopeless. But let's, let's try a different system. Ok. This time you're going to choose two comments. That's the, I suggest you try, try to disperse your attention between people with different and when one of those three people stands up, you stand up. But if both of them stand up, you sit down here, that's the only rose. That's it. So I'm gonna ask, uh, mother, would you mind standing up? You please? Yes, I was actually flipping a paragraph. Both of you started, stopped again. Ok. Um You about so good, good. Keep going. Yes. Try to stand up as quickly as you reasonably can. All right, sit up and stand stand up and sit down quite sharply. Two people standing up, you sit down, one standing up, you stand up. Yeah. Right. Oh, ok. Quick. Quick, quick, quick. Ok. In the first example, I had predicted that we would quickly reach a 76 which was everybody standing up with that exercise. Do you think we'll reach the same thing? Yeah, I think it should continue indefinitely. Ok. So, because the rules were really simple, but they were so they were complex enough to create quite a complex ano that maybe II predict that it wouldn't have continued to be totally random. But that patterns within 100 rather like they do for Y Starlings. OK. So systems of parts, those parts are connected together in various interesting ways. Let's see. Shall I try hitting that one? Brilliantly, you already mentioned in your definition without being prompted the notion of networks that systems are networks and just take a look at the screen here because the types of network are very different depending on the types of relationships between the parts. Uh So you can see on the left here, there is decentralized in, in the middle, so centralized, decentralized and distributed where there's evenness of interaction between the parties. And this is not a mental question, but it's just a little question between you and the next person. Please try to attach um the network to the specific example. 30 seconds, right? 130 bye. I I see. OK. Colleagues. Very good. Uh So Bristol Medical School is a to the totalitarian state Crystal Medical School is a decentralized network potentially because you've got different year groups that have a relative degree of autonomy. But you still have like a center point which is like the program directors and so on. The Russian Federation. As far as we can tell it's centralized, it's all the power comes from one place. If you've ever been to Russia, you feel that very strongly when you're there and the rain forest, like there's nobody's exactly boss of the rainforest, right? It's just a, a massive pattern of interconnections, maybe some hierarchy between predators and prey and so on. And the extent to which human beings are healthy relates a lot to how network they are. So this is the Alameda County study. It's one of the most famous what we call it longitudinal cohort studies in the whole of epidemiology. It's got very high level of follow up. I think Alameda is California, if not mistaken. And they showed that the people who had the most social networks had a relative risk of dying of like tt times two, less than the least connected people when they'd account for as many other confounding variables as they could. And this research from 1970 you see, it's like 20 years before social networks were in everybody's parlance. Um So we have, we have parts often hidden, we have those parts in interaction in, into networks. And I just wanna mention a type of connection that you'll have studied at probably G CSE, you're probably studied at a level and you're probably gonna study it at 11 o'clock today because it's the basis of all physiology. And that is what? Oh, I'll tell you why he's there in a minute. Um It's, it's, it's feed uh feedback loops. OK. So, um I've created a slightly new vocabulary here because how are feedback loops generally divided into and three times diposis? Ok. So, because pulse is negative, so many complications, I prefer normative and amplification. So no function is to keep whatever the parameter in question is the same. OK. So that's fundamental in your home. It's also fundamental in lots of other systems. So in this like now we are obeying a whole bunch of social norms, there are social norms about how you dress, how I dress, um how you behave, whether you shout out, whether you start singing during the lecture or whether you stay silent, whether you ask me questions or you let me know what I'm talking, et cetera and those, those social norms at a cultural level, which we even even within science, the paradigms we studied last term are examples of scientific norms. So if you move outside of that norm, you get feedback that makes you um obey whatever that particular norm is. And um I just thought, I just thought I'd be very impressed if anybody knows why at this level. OK, South Korea were expected to win in the Asian Asian football competition, correct? And they lost in the semi finals. And Jurgen Klinsmann Dutch, he was fired as the manager and one of the reasons he was fired was what he was too happy. He was smiling too much in press conferences. Like for instance, after they lost, you can see on the left the more ex socially expected facial expression for the Korean footballers having lost this competition that they expected to win just using it as A I like in my election to sort of take things straight out of the news. It struck me that he failed to adapt his behavior to the social, non expectations of Korean football culture. Cos it was just too silent and they didn't like that. Cos there sort of, you know, cultural things are around shame and high expectation that hadn't been met. So why be happy? They might say, I don't know, I don't really know. It's a guess maybe just show you uh this is the sort of thing that uh you will be studying at 11 o'clock. Very key. Just an example of a normative loop that you've probably known about since G just to remember, it's complex, isn't it? Because glucose also uh low glucose releases glucagon. So there's a separate parallel feedback system which reinforces the normative tendency of the glucose insulin system just as a little. It's quite interesting to think about the pathology of these systems. Cos they're remarkably similar. So for instance, what do you get if when glucose rises? You have no insulin release from the pancreas. What's that called as a disease? Yeah. Which side try again. Correct. Ok. You get a rise in blood glucose but because of uh autoimmune condition of the pancreatic basal cells, you don't get glucose is if that's one type of uh feedback of um the other one, you get plenty of insulin, but the muscle cells and particularly the adequate tissue is not, is is what it is not sensitive nature. Therefore, that produces matter. Would you like to suggest the type of diabetes here? Correct. So that's type two. So you can see there's different types of pathology. Um I just wanted to think I'm just trying to, yeah, I mean, Klinsmann in a way, he failed to produce the serious expression that he should have produced when the levels of shame had risen within Korean culture. Say um um that you can of course get the opposite problem in feedback groups, which is that you get too much of a response um to a sym and can anybody think of a, a medical situation where you get a little and you get a little syllis and a very big response that you don't want a little bit. Yeah. How tell you in the form her posy axis. OK. That's a, that's a catastrophic immuno activation due to time. I have a video that I could be. I had a patient who took a single tablet of um penicillin and very diet totally healthy patient that just got to the phone in times to tell us the whole story that shows you another time. OK. Does anybody know somebody in their social realm? But you know, you just said that little thing to her and she took it, took it the wrong way and just misinterpreted what you were saying in an unhelpful fashion. OK. We know this, we've probably done it ourselves, right? So that is an overreactive system and these are all really phenomena of the same type. The anaphylaxis would be an example, not of normative feedback, but of top left amplificatory feedback. Now, in physiology, mo a lot of the amplification feedback moves have to do with sex. OK. So the most common, the most famous example would be the one illustrated here because as the neck of the world stretches during these uh later phases of labor, it, the fibroids go to the posterior ge causing it to release swab, sir. Which hormone uh you're not sure. OK. Pay for better attention. You might sorry, correct Oxytocin. OK. So the Oxytocin causes the uterus to stretch further, producing more Oxytocin. But why does this process end? Where go give me this for? Um No, I understand. OK. It ends with the birth of a child. OK. So that's what's happening here. So um if I may sexual orgasm is another thing which builds to a CSC and then finishes and ovulation is another example of a positive feedback loop. The thing about these positive feedback loops is they always are, they always have a finite conclusion. They don't persist. If you have a positive feedback loop that continues, then you've got, you've got problems. OK. So the key thing about these feedback loops, these um normative and amplificatory feedback loops is that they apply at all levels of what we defined in the first term with the whole arm. So the same principles are going to apply. And um yeah, I think um let's have a look at an example of this. So I'm gonna start at a bodily level with this. So this is a curve of body temperature against time. Now, you can just say it's a bit fuzzy but it's uh it's like a 20 a 28 hour interval. OK. So it's, it's a, it's a cycle. It's a day measuring um temperature on the left with time along the bottom and, and I'll just give you a little heads up that it's a study of body temperature when people have a hot bath. And that explains the spike. But I want to move now to menter because I want you uh I wonder will it work if, yeah, unfortunately, the, the the graph has gone away. But I want you to tell me what you notice about that graph. That's your challenge. Like what just say anything about it. Just what do you notice cos it's quite important. Excellent. It does indeed good. It fluctuates. It does. Yeah, those try to get me. There is ok. What happens on my head this bit like that? I wanna go back here. Ok. I'll tell you what I really, I really want to go. This may confuse the thing totally. I'm just learning how to use this guys. Haven't quite cracked it. Ok. So let me, let me, let's have a few things. So a quite a few people said that there's very, let's ignore the spike generally in that. So people said that it was lower at night than it was during the day. And that's perfectly true. And just a little sleeping tip if you want to sleep, better, keep your bedroom cold, the body like sleep cold, sleeps better in the in cooler air. Second of all, there is a point to point variation. In other words, there's a macro variation over 24 hours, but there's also a constant variation uh from you might say minute to minute, probably 77 if you could. Uh and what do you notice about that variation? It's not like very much. But um you've also got a physiological intervention of the hot bath and how quickly does it get back to normal? Obviously, by other feedback loops like um blood flowing to the surface of the body, cooling the blood, right? Ok. So bear with me here. That's a physiological cycle. Agreed. Now, I'm gonna look at another cycle this time on a completely different scale if my ability to do this once. OK. So roughly, so this is a graph of temperature against time. So it's the same graph except that the timescale is 800 1000 years. And how do we know the temperature of the earth so long? Actually, I don't know the really know the answer to that. I know where we get the answer from, which is II, OK. So if you go down the Antarctic ice, you go back in time, you can go back about a million years. In fact, this is to 800,000. So that's the oldest ice on earth that a million years old. And you can see that it varies in a cycle, just like the human temperature variant in the cycle. And also that um within that variation, there's constant variation. So at a micro mic macro level, at a micro level, there's variation. Uh it is a, it is a ment but I'm not gonna involve a, what are the areas going to do? There is a little side effect. So coast coast cells known as ice ages, ice ages. OK. So these are the ice ages. Uh they may re remember people forget the ice ages though. They're only just the top of the earth. There is never ever in history. The whole earth on I see it's just that holes get icy and it gets down as far as like Europe and then it gives up and goes back again, but this happens in a cycle. OK. So do you see what I'm saying? That the two things are really just the same at different scales? I think we'll ignore that. OK. Here, I've done something else which is I've added a second graph onto the temperature time graph, which is the CO2 time curve. So we have a very similar curve for carbon dioxide as we do for temperature. And the carbon dioxide is itself controlled by a really deliciously complex feedback system which I'm gonna show now, don't freak out that's the carbon cycle. Ok. Without looking in too much detail at the graph. Shout out to me. Where do you think carbon dioxide gets into the atmosphere from? Huh. What is I get? I just get that give me an example from fossil fuels. Ok. So that's a bit of a new one. Not really speaking for fossil fuels, but yes, so that is a very big one. Anywhere else. Any other major sources that you know of that make the news volcanoes, volcanoes. They, they don't, they cause a lot of trouble to combat. And the third one is, is probably, I mean, there's probably loads of places, but I'm thinking of plant and animal restoration. Ok. That's another, I don't know how significant it is and we absolutely know that the cars are in the atmosphere at the moment is a lot of it's from fossil fuels because it's a different carbon Aceto to the isotope from, say volcanoes or from uh plant and animal respiration. So, just like, so the point here is that, that the earth has, its got, has got these macro cycles. Um In fact, i it's very good at keeping the carbon dioxide levels of the planet constant because do you know where m I think it's something like 40% of all the carbon dioxide that we've put into the atmosphere from fossil fuels. Do you know where it is? Now? It's in the water, it's in the ocean, that's how it works. Um And of course, eventually it will become uh um shellfish and form, form sedimentary metamorphic rocks and go through this massive MC macrocycle. Now, um things get a bit interesting when you start to understand w high carbon dioxide and temperature related. And as I understand, and it works like this, that um when you have more co when you have uh more carbon dioxide, the temperature goes up by mechanisms that we'll learn and uh the plants, particularly the algae, they absorb the carbon dioxide and try and bring it down. And that's roughly, I think how the carbon feedback loop works. I don't really consider this necessarily a true negative feedback loop because nothing alters the sun, right? You can't alter the amount of energy coming from the sun. But that is a core piece on that screen of plane physiology. No question about it. That's the greenhouse effect. And you remember my question, the ultraviolet radiation comes into the earth, it gets bounced off the clouds, the proportion that reaches the earth is remitted as infrared radiation. And that's the type of that's heat and that's the type of radiation that gets trapped by the carbon dioxide and by the clouds. So that's the mechanism by which greenhouse gasses work of which carbon dioxide is one of the most well known uh because of these regulatory processes. As you remember, I said, we know that the body has loads of regulatory processes. We studied the situation with glucose a moment ago. The earth itself has dozens and dozens of similar regulatory systems. And this is what led a guy called James Lovelock in 1974 to propose the Gaia hypothesis. Gaia being the Greek goddess of the earth. And that is roughly what the hypothesis states. And this in turn brings up a really interesting philosophic question. I rather like I asked you to decide whether you thought the soul should be part of our understanding of the whole person. I'm gonna ask you a similar question now, which is, do you personally consider the earth to be a living system? And it's up to you to decide what you mean by living or indeed what you, you mean by the earth? OK. That's interesting. I mean, I, I remember when I was like doing o level biology, you know, the teacher said, OK, what is life and it had things like can reproduce and I didn't know whether the earth it didn't strike me as possible for the earth. So it does hinge somewhat on what you mean by living. But I think unequivocally self regulating. Uh So thank you for that. That's interesting. OK. We're in the home Straight cos that's, oh no, I didn't want that. You gotta learn to use this damn thing. OK. So guys, we've talked about parts, hidden parts networks and we've talked about different types of feedback, um normative and amplificatory. And we've seen that the same principles apply at the micro and the macro. So for instance, your carbon dioxide levels are carefully maintained in your blood. And similarly, the planetary carbon dioxide levels are also maintained by very complex and huge feedback systems which lead to the concept of the earth being a living system. That's roughly what I've said so far. I want to finish my lecture, which we'll finish in about seven minutes, talking again, moving a little bit into pathology because yeah, we doctors, we love pathology. And I want to remind you uh a little concept that we had in, I think it was actually the first lecture you ever had at med school myself. And uh Professor Tina Turner, we talked about this concept of system latitude. My system latitude is how far you can stretch a system before when you uns stretch. It, it doesn't come back to the way it started Ok. So it's a sort of maximum capacity of the system. And you will remember, I said, you know, did your little sister ever get your slinky and do that to it? And now look, it's broken, it won't go back to where it was because it was stretched beyond its latitude. Ok. So you get the theme here, you know, as below. So above, you could say, um that, um a very famous piece of work that's annoying, the way that code sits there, isn't it planetary boundaries? Uh a very respected paper published nature which is the leading journal by the Stockholm Institute, make this attempt to define the latitude of different systems for the earth and they find 10 of them. And you can see that um biodiversity isn't going well, not least because that's the sort of failed feedback system because once a uh plant or animal is extinct, then you, you can't homeostasis, you can't bring it back. Uh And we're, we're in the middle of a aba biodiversity crisis, nature crisis really. But if we take another one, climate crisis, things are bad but not quite so bad. Um This is another physiological curve. I, you know, in my view, all uh well rounded, sophisticated modern adults should know this because this is carbon dioxide against time since the 19 fifties measured in an observatory on top of a volcano. Wear. Hi right on top of it because in Hawaii, there's very little industry So you're not gonna get carbon oxide from the results. It's very mixed. The carbon dioxide mixes through the whole atmosphere, which by the way is only about 12 miles thick, which is the distance from here to back. That's how, that's how, that's how little atmosphere we have. Um OK, so uh bonus points this could come, this would be a tough question in an exam. But why is the peeling curve jagged like this? OK. We don't have the time. Yeah, I'll tell you because most of the plants on the planet are in the northern hemisphere. In the nor northern hemisphere summer, the plants do what they suck the carbon out of the atmosphere into the zone. And that's why car drops during the summer, I should say the northern hemisphere summer and the southern hemisphere uh summer it comes up again because the plants in the north are dead and the carbon oxide I had to amend my slide. You can see top right that we, we talked about this homos stasis of carbon oxide against time, but the current carbon dioxide is not homeostasis. So remember I said the, the, the, the the historic peak was about 300 parts per million. And now you can see it's 421 parts per million carbon dioxide. That's the sort of fact I'd like you to know and remember and if it wasn't for Gaia buffering the carbon dioxide into the seawater, I don't know what this level would be, but it would be much higher. And the implications of this on the planetary system are pretty severe because the carbon dioxide in the water renders the seawater acidic and that has the effect of majorly influencing the marine ecosystems. For instance, here you can see an example of coral bleaching. Ok. If you're aware of time, I'm not going, I was going to do this, but I think I'll miss out that I'll just finish off by, by just reiterating er, where we are with the, the curriculum going forward. Um, you've studied planetary physiology. Next term, you'll study planetary pathology, as I said, and the pathology pathology, as I see, it falls into three main categories. The first category is greenhouse gasses and climate change. The second is biodiversity loss. And the third is impact of pollutions in the, particularly in the water supply. Much of it, not much of it, but significant proportion of which is directly related to medicines and the impact of medicines in the water supply. And yeah, in the third lecture you, as I said, we're gonna be studying, um, we're gonna be studying the impact on healthcare and also what healthcare can do about this. And this is one of the reasons why we don't want to destroy nature because it's a source of medicines and something like 50 per cent of all chemo therapeutic agents come from the