Wednesday, May 25, 2022

2. Architecture of Lungs | Conducting VS Respiratory Zones | COPD | 1stYR MBBS Physiology

This this compared with the old song what is the old song doing old song is saggy delight yes elasticity is less yes so when you put your foot in it it doesn't really matter whether you put it into your foot your hand doesn't matter because it's .

It's loose why because the structure has been damaged by by by by the use of this sock so elastic fibers are not new they are saggy and you know they are they're relaxed this is what happens when the lung ages so the material lung is made of laxes in particular .

The elastic fibers in it they lacks so a new lung it's uh easy to expand easy to expand more and more and it's very very effortless mark these words now a default for first year students is that you only concentrate on lung expansion if you don't get this point you will get it when you start .

Reading you are biased you don't think about expiration that is done let's think about inspiration however as you now go along and as we start discussing by the way i've posted some material on the facebook .

It is a clinical scenario please refer to it because i'll be referring to it as we go in the first few lectures definitely so there are disorders which affect the lung architecture in such a way that inspiration might not be a problem but expiration becomes a nightmare .

How can expiration ever become a nightmare this is a difficult question you would think and i know you would think that inspiration should be a problem well it is yes but most of the prolific famous disorders of respiration .

They mess up the expiration profile of the guy why am i pinpointing expiration if you have a difficult expiration what's the problem think think about think if you are the lung think if you have taken air in and you can't take it out wouldn't the next inspiration will also .

Get effective we have trapped air and we can't seem to expire it properly so if say let's say i'll quantify for you let's say we move in five units of air inside with ease however we can only expire three units out two units remain there .

Which shouldn't in a new lung they don't so now there's we are stuck with two units what do you think will happen next respiration doesn't stop does it so the next inspiration will bring in five more units the two extra units are sitting in there from the last expiration because it .

Couldn't expire are you following this whole thing now so you take in five more units again you can only expire three units so now you see that lung is now loaded with old air old air air that is not fresh that that thing that you bring in the five units that you bring in from .

Outside that's fresh air not the stale air that stays behind because it has been transacted with oxygen has been extracted carbon dioxide pumped in and it's sitting there and it's increasing and fresh air isn't coming to remove it problem big problem eventually would you be able to bring in .

Five units of inspiration air because there is a finite amount of volume inside the lung this american association logo if you can't breathe nothing else matters i really like this okay so uh it's it's better that we start the clinical stuff right from the back .

Right from the goal so look at this gentleman on the left and then compare him both pictures are his compare these pictures with all the gentlemen on the right see the difference soak it in you won't be able to understand everything of course this is your .

Literally the first time you're seeing this but i want you to just have a visual of these two people what is the what is the one difference that you find the one difference that you find anybody from the back g area .

This guy is big this guy is thin yes so this guy's bloated this guy isn't yes just remember it just remember this another thing that you would like to remember is the bloater is blue b for blue b for bloater bloat hula yes so blue bloater this is a blue bloater obviously it's a .

Black and white diagram so pink buffer it puffs a lot like that he just sits blue stuff blue lips blue nails blue mr blue sits there depressed shallow breathing he breathes not very uh audible this guy looks like a steam engine pink buffer puffs .

Okay it's difficulty exhaling the trapped air that we were talking about earlier okay he has to push air out so inhalation is not a problem in this one however pushing it out is a nightmare hence look at his physique if you really look closer you will find that his chest as as .

As compared to the rest of his body is broader look at his chest look at his shoulders that one there normal chest normal chest of a guy his physique but look at him he has a broader chest and on the side view you see that it pouches out bulges out on both side .

We call it barrel shaped chest it looks like a barrel and gets worse when his condition worsens that's the third point look at the condition and just remember it we will be visiting these two conditions as we move along that is chronic bronchitis this is m5c .

Once again blue motor chronic bronchitis pink buffer emphysema condition called copd anyone heard of it so people have heard of it chronic obstructive pulmonary disease c o p d this .

Is a huge issue for human beings today disease causability list of who lists copd in the top ranking diseases it causes diseases as a disease its profile is really high up it also is in another list which is much more somber than this one .

Diseases that kill people so mortality morbidity and mortality morbidity he's very he is looking very morbid today morbid female disease morbidity disease mortality killed dead finish so copd features in both lists the bad lists bad worse so copd kills a lot of people actually .

Global okay m5 chronic bronchitis plus m5 sigma is equal to cop so c of e d presents itself in the clinic either as a blue bloater or a pink buffer or somewhere in between in biology rarely can you have a mathematical accuracy between .

Anything it's always approximately maybe somewhat perhaps and so on and so forth there are there is no arithmetic accuracy in biology this is not mathematics so some patients they fall in between these two presentations and you need to work it work work it out the good thing is you .

Just don't need to look at the patient we have tests which we later on see that can pinpoint you in the right direction okay what exactly is he suffering from bronchitis element or emphysema which one is okay any questions until now still no questions good brave class .

Intelligent class i would assume or conclude whether rightly or wrongly they can measure when i badger you guys see that can someone have both of them yes yes that's what i said both of these features you may have a bloater who has some features of the buffer any in between so the disease .

When it starts off it can go in the blue bloater path or the pink buffer path or stay in between that this guy has the worst of both worlds the biggest feature of chronic bronchitis is blue gluteus and emphysema is being performed and .

When when you read we read we'll read it along we'll follow these two why these two because they are really high in prevalence in the world as i just mentioned they're really common and you will get a lot and and then people are stupid .

And stupidity also is increasing stupidity hardly ever do i say random things here i don't say random things here what has stupidity got to do with copd everything i said people like who doesn't like candy i like him .

So candy question candy question is a competition that i that we have sometimes you get 20 seconds to pull in the thoughts together then i ask you a question specifically the one who answers gets a candy from me i hate going to the store and bringing candy so if you don't .

Like me answer the question the hands were one two three four five six six hands we start from you simple answer brief we are the ones causing the solutions i know that you guys don't smoke it's just you answered smoking so one two .

Three four i hate you guys because i have to get you get four candies now well done please sit cr corner who is the cr in this class see ya would you remind me online four candles thank you smoking it's optional and you're stupid to smoke and smoking once it start to .

Create and this is a statistic i'm not just fear mongering here this is a statistic when copd starts developing in the lung look at the situation here look at the situation when it starts developing this happens eventually when it starts to develop when you are .

Puffing your worries away what starts to happen is the lung architecture starts to change then either you become a bloater eventually or a buffer and the thing never reverses so so so if this is the health of the lung starting from 0 to 100 percent you are at 100 .

And then a silly friend of yours thought that it's cool to smoke and put you on smoking as well all right and you were silly enough as well now when you start smoking after some time the lung health will start to come back you will be at 95 percent 19 .

Profs okay 17. it happens okay now what i want your attention to is this seventy percent is fixed even if you quit today in the profit mid prof and somebody takes that and throws it away you can't replenish the 30 that you have lost to stupidity this is the problem with copd .

In one word irreversible you can't reverse the damage once it's done it's done the sock you have messed with the sock it's not new now and in a new guy there's an old sock if that makes any sense this lecture will be uploaded online and i hope they don't skip .

Because if they skip right to this part they say what what is going on it's a government's class same can you can you tell me which one is the bloater obvious the bloater the buffer and now you know okay they are thin they are uh they're not thin by diet this chair .

Might be a good healthy big guy but another candy question why is the pink puffer thin usually thin what's eating him up candy question 20 seconds you're on i like your class already we are already down two candy questions here .

Has has increased or decreased effort to breathe has increased or decreased increased energy anybody else who said energy or related to energy either you guys are good or either i'm .

Asking easy questions so this guy has a lot respiration is an effortless thing in the normal healthy person this is a great point actually you use i think enough a fraction of your energy in the effort of respiration it is so smooth everything is smooth .

You don't you don't even know you're respiring right now but now you do because i've just made you attentive about it but just quietly going up and down up and down and hardly any energy is used but look at this guy he has to put energy every time he exhales can you .

Imagine that every time you exhale you need to push against a ball that's how he feels he has to push against the wall to get the air out it's called air hunger because now he can't introduce more air in his system so he's hungry for air although the sock-like situation is in him .

But since that residual air is sitting there it's hampering now new air coming in as i just explained are there any functions of the lung these are the learning objectives this is good to know where we are in the lecture right now uh are there any functions other than .

Respiration that the lung performs well done well done gee so acid base where did you know that lung has a power to plain acid waste balance respiratory acidosis respiratory alkalosis that business negative both respirations are related i'm saying non-respirational function a very important point especially in the .

Ear of cobalt anything else that the lung plays everything is homeostasis you can put literally everything in there immunity immunity it has what type of you've just studied blood macrophages alveolar macrophages are there in the lining of the respiratory system .

And it's it they have to be there why because you're inhaling all sorts of rubbish but they need to be taken out right at the point of entry where it comes in touch with blood so in between there are macrophages that eat that stuff up from the pollutants that you inhale in air okay then we look .

At anatomy uh three and four we will look at in the subsequent lectures next who also features in one of the today's uploaded slides next functions we've done okay so metabolism it also converts it also does some metabolic activity anyone .

Do we know angiotensinogen angiotensin one gets converted way up lungs and which enzyme does that shabash ace angiotensin converting enzyme it sits in the lung so it waits as soon as blood may angiotensin one comes through it converts cleaves it converts it in .

Angiotensin ii which is the biologically active agent so we've talked about immunity gas exchange we already know let's look at some anatomy okay so we've already talked about this it's a remarkable piece of engineering that tennis court example fit into .

Uh the four liter thruster cage okay upper and lower airways this is pure anatomy you will be covering it in your anatomy classes it's not really upper airways basically condition the air what do we mean by that what does air conditioning mean making it moist it's dry usually warming it up .

Uh conditioning it so that because the inner side is delicate inside you have homeostasis so we are breathing this hair this air is not conditioned and and the inside the lung you need us if you need air at a certain temperature which with a certain uh .

Vapor content else you will dry things up so you need to be careful what you breathe in that's why the upper airways are designed to do all of that conditioning okay the anatomy you'll see in anatomy classes these are the lobes again these are the lobes that you will be grilled into .

By anatomy people this is our stuff so predominantly it is elastic what about the rest its collagen its other type of fibers adipose vessels this that the other but i i want you to make a concept right here take a you know a tree a typical tree .

Stem victory that the calendar dream yes somehow make it small make it small that fits your hand yes it's now this is the tree right on your on the palm of your hand stop okay now flesh out the leaves so that it's just a branchy structure .

Stop branches yes invert it take a beaker and ask your mom to make rafan jelly and put in the beaker do we know what refined jelly is jelly the best kind if it can be called best so it's refined you know the jelly thing .

Put it in there and now it's still warm by the way it's not solid mum just made it it's nice and warm right now it's fluidy when it gets cold it becomes solid yes you're with me right okay it's still fluidy you put your miniature tree .

In it put the beaker inside a fridge wait for 20 minutes as long as the jelly takes to solidify take it out you have the lung it is this is the essence of the normal healthy lung the tree represents the airways the airways the stock is the trachea .

Branching extensive and you took a very big old tree before making it small it was very big and it had a lot of lot of branches you know what i'm getting at i'll be like it needs to have a lot of branches this tree does and the jelly represents the the material the sock the material of .

The lung so it's very flexible it's very flexible it is extremely flexible okay distensible however as soon as you pull it apart and leave it what would the jelly do if it can be stretched apart .

It will come back to its original situation because it is elastic this is literally the lung so predominantly it's elastic airways the whole thing we are moving one step further now the airways are of two types the initial airways are referred to as the conducting .

Airways or the conducting zone their role is to conduct air be a channel between the outside atmosphere and the innermost parts of the lung in the middle you have the conducting zone so initial air is trachea principal bronchi and the big other branches of bronchi .

All of them are conducting zone deeper tree deeper part of the tree is referred to as the respiratory zone this is where what does the word respiratory give away so if i were to ask you just take a guess would there be gas exchange in conducting zone does gas exchange .

Take place across trachea next it doesn't so conducting zone does not involve gas exchange respiratory zone does thank you first so this is the trachea the principal bronchi and then this is the rest of the tree which .

Penetrates deep this whole thing is the respiratory zone this thing here is the conducting zone when we blow this up look at this look at this whole table here it's very nice from zero ie what zero means is no division as you go down it all starts with trach .

Here doesn't it tricky is one two as soon as it divides this is the division counter okay so it has divided once to become two then further division and so on and so forth so the first 16 divisions from zero to the first 16 divisions that comprises of .

This is a viva question don't don't write things you should remember these things okay so the first 16 divisions are actually conducting zone they don't involve in respiration in gas exchange but of course they their road is very important .

And there are features which in a viva we can dissect out from you there are features of the conducting zone which are very peculiar specific to the conducting zone not found in the respiratory zone okay the rest from 16 onwards 23 it's lots of division as you can see there are lots of division now .

And this whole thing now is the respiratory zone let's see the names quickly so drake had started a trachea then came bronchi then bronchioles and terminal bronchiole is that station where conducting zone becomes respiratory zone yes and then you have respiratory .

Bronchiole alveolar duct alveoli or alveolar sacs okay this is the complete uh breakdown of the respiratory tree inside that jelly-like thing called the the parenchyma or the tissue of the lung the tissue of the lung gets messed up in smokers and the respiratory treatment .

Concept you can do two nasty things to the lung either you can mess up that rafan jelly the parenchyma the tissue of the lung which smoking does by the way you know what smoking does smoking breaks down the last literally i'm saying it like this there is a whole sophisticated way of .

Saying it but basically what it does it it breaks down the elastic fibers so they do they're not continuous they're broken down that messes things up because it's nice one spherical thing when the lung comes up it comes in a symmetry .

But if you have broken down stuff then the symmetry goes then it's like a balloon if you try to inflate it this is a good example if you try to inflate a balloon while you are squeezing it like this and you are pushing air in it will out pocket from within your fingers .

And get trapped within the fingers it will be a very funny little thing as compared to when you hold its neck and then blow in it then it becomes symmetrical so imagine this now when you mess up with the parenchyma it will expand in the healthy parts but the non-healthy parts will just stay .

So there will be a mismatch in expansion similarly mismatching in deflation in contraction because there are stuff which are not continuous they are broken number two very importantly it replaces elastic tissue with fibrous tissue fibrous fiber doesn't this wire won't expand you know just imagine .

I couldn't find a rubber band i wanted to just tell tell you the rubber band thing look at the double band you extend it if it's a nice strong rubber band it will it will stretch as long as you can i mean don't break it but you know it's nice .

And when you release it it just goes back to its original length this is how the elastic fiber of the lung acts however when you replace it with a thread thread that thread does not stretch does it it doesn't so smoking does both of this so either .

You mess up the tissue of the lung or the airways themselves can you give me a condition which involves airways it's very famous people are born with it asthma well done asthma so in asthma what you do but what happens is an inflammatory reaction you have .

Your great inflammation an inflammatory reaction happens inside the wall of the respiratory tree all sorts of uh secretions are there it's thick and when it becomes thicker than normal exactly the same thing happens air entry is a problem relatively but air exit is a bigger problem as soon as .

You now press apply pressure on already constricted tree it just collapses inside because the pressure has increased we will do it uh as we go along okay just go through it ask me a question if there is a question i've already explained it .

That's a very good question okay just hold that question till saturday we will answer it on saturday good question i will forget it you have to remember it come on hurry up name the red no question about the red no question that's why i'm good but do remember the red .

Okay conducting zone blood supply bronchial vessels respiratory zone blood supply pulmonary vessels there are two blood supplies of the lung bronchial pulmonary very important the one that is involved in gas exchange is pulmonary blood not bronchial blood .

What's the what's the function of bronchial blood then to nourish the lung itself to nourish the nourisher it's it's it's tissue right it needs to be alive so its own blood supply is bronchial however the pulmonary blood supply is for oxygenation and all that sort of okay this stuff is we've done 82 meters .

With age and size tail adolescence you're late your alveoli have attained their size okay now you can only mess with them you can't improve them okay dollar since it increases after that the only they can only increase in size .

But not in number i beg your pardon so you they have stopped multiplying after a dollar since they can only increase in size if you are good in your health if you exercise etc etc then they can only expand in size not in number number is fixed and smoking irrevocably decreases the number that's why it's stupidity number .

One plural i will explain plural first thing on saturday however i brought a little gift for you what do you see one slide this was the there are two strides now what do you see two sides .

Two sides yes it's like a magic show i can't seem to separate them i'm not kidding i can't separate them but i can slide them i can slide but i can't separate let me try again i can't i've done a trick what's the trick boom try it try separating maybe i'm just tricking you guys .

Vertically no not like that vertically just try to pick it vertically so we have a student here trying to pick oh not like that don't break it but did you feel the friction yes yes when you put it like this in this situation look in this situation you can't pull it apart .

You can't you can't pull it apart why once if these were two brand new slides you could you could do that these are very brand new slides but whatever i put in between elfie if they were healthy i wouldn't be able to slide them water i've put water in between just a couple of drops .

And look the magic that we get what am i getting at so very briefly the lung is encapsulated by two membranes one is visceral pleura right outside the lung visceral plural and outside it lining the inside of the thoracic cage is .

Parietal plural visceral bridal and those two membranes interact with each other like this and they are wet on their inner side so the wet surface is parietal pleura this one visceral tourer this one they interact such that they can slide on top of each other .

You can't pull you should not be able to pull them apart or answer that is exactly what how they're designed so there is a space in there because we know there are two you know now initially you didn't i showed you you said this one slide so if you just look at them these .

Membranes they look they appear like one structure however they're two so there's a conceptually not conceptually physically there is space in between them which should never be occupied just that thin layer of fluid that you can't see that .

Should be the only thing between these two membranes it should not be anything extra between these two membranes else we will go to amit for khan's land problem saturday okay so these two plural they slide on each other so when the .

Lung needs to expand not a problem it will expand bulge the visceral pleura will come against uh it's already against the parietal pleura and they will just pull the lung out and when you want to constrict the lung deflate it they will just push it in that's it .

That's all we need to know at the moment about these two linings these two membranes if god forbid you were to introduce any stuff plus blood air ironically air as well in between these two plural layers bad things are it's not good for us and we will study it in the subsequent .

Lectures so if you have air in between these two membranes we call it pneumothorax right and hemothorax is blood so if you have accumulation of blood in between these two where do they go in between these two if any blood comes they will separate .

They separate you have a problem they don't they can't separate you if you have air this is irony why am i saying irony because inside the lung you have air but you can't have it in between these two this is the iron abundant of air inside the lung but outside no big no if you have .

Outside air lung will collapse why would it collapse we will talk about that okay please revise this lecture uh you will have it on youtube very uh today by afternoon inshallah and we'll pick off proceedings from this onwards on saturday 9 00 am in this article .


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