Hello, hello, hello buddies. How are you all doing? A very warm welcome.
Yes. So welcome to the NEET 50 days challenge and in this NEET 50 days challenge, so as we have promised you that we'll be completing your syllabus, as you will be appearing for the NEET examination in this May. And before that we have to complete the syllabus.
That is the reason we guys are here. And now I'm going to start a new chapter. which is your excreta products and their elimination so hope all my students all my buddies are ready shall we start hi suresh how are you so come on guys first of all share with your friends and call your friends here let's have a uh fun session let's uh make this session you know you know where there will be a lot of students there will be a lot of interaction there will be you know the doubts and i'll be having again i'll be having a close look a look at the chat box so whatever doubts you have you guys can ask me in the comments hi good evening sanika how are you nice name sanika suresh hi suresh hello akash good evening good evening to all my students so you remember in the previous session we have done structure organization in animals and now uh another chapter which we are going to start is excretory products and their elimination So different type of excretory products are there and today we will see how we can eliminate them all. So are you getting my voice now?
Let me check. One second. Let me check. That is everything fine, clear?
I guess yes, everything is fine. Am I on my? Yes, yes, yes. Hi, good evening Bertini.
How are you? Very warm welcome students to this class. Yes, okay. Okay, okay, okay. First of all guys, call your friends and yes, let's start the session.
We are already, time is, your time has been started. So let's start. So what will be today's target?
We'll be talking about human excretory system, mechanism of urine formation, function of tubules, so many topics are there in this chapter. So we'll be discussing each of these one by one. So first of all buddies, we have to start. Yes, good, good, good, good. I am also good.
Okay, so first, before starting the types of different excretory waste, okay, I will do one thing, I will use a blank slide, otherwise you will get confused. Okay, so buddies, when we talk about excretion, excretory products and their elimination, what comes in your mind? One thing comes in our mind that there are some waste material produced in the body and that waste material we... removed from the body.
What are those waste materials? Now everyone will say, ma'am it is the urea. Urea is there in the body and we have to eliminate it. Bodies, again I am saying urea is not only the waste.
There are other wastes also. What are those other wastes? Sometimes we consume lot of you know, ions, we take lot of ions in the diet, we take lot of water in the diet.
So whatever is there in excess we remove them. When we talk about those excretions, excretion not only involves the kidney, there are other structures also. They play a great role in removal of substances.
The first word which I'll be using over here and you'll be shocked, the first word is the skin. Yes. Now you'll say, ma'am we don't live in water, we do not eliminate nitrogenous waste or any other waste from the general body surface. Now I'll be saying no.
We have sweat gland, we have sebaceous gland. So with the help of sweat gland and sebaceous gland, we excrete so many substances out of the body. For example, for example, okay, I'll show you.
I'll show you everything, everything. Okay, so here, if I talk about lungs, lungs also helps in elimination of substances. Here, if I talk about lungs, lungs eliminate 200 ml per minute of carbon dioxide. This much carbon dioxide our lungs eliminate. This is the exact data from your notes, from your NCERT only.
So lungs also helps in elimination of substances and carbon dioxide is also a waste from the body, isn't it? Now the next thing is if I talk about a liver. Liver is also that structure which helps in elimination of substances, which are not useful for us.
For example bile, bilirubin and biliverdin, cholesterol, vitamins, steroid, hormone, drugs, they are also eliminated from the body. And how? with the help of liver. Now the next thing is if I talk about saliva. Saliva also helps in elimination of small amount of nitrogenous waste.
Now the next thing is skin. Skin also helps in elimination. For example we have sweat gland.
In the case of sweat gland, sweat gland, what is the basic function of the sweat gland? Basic function is the cooling effect. It helps in providing the cooling effect. Now the next thing is excess of you know the salts, water. they are also eliminated.
Lactic acid is also eliminated with the help of the sweat gland. Next is the sebaceous gland, sebaceous the sebum, sebum or the oil gland we have on the skin surface. So that also helps in elimination of what? The oil, sterols, hydrocarbon, waxes. Now you'll say ma'am what about kidneys?
Yes kidney also helps in elimination of substances. How? But that we are going to study in detail in this chapter.
but do not be confused that other organs do not play a great role here you can see liver plays a great role lungs also helps in elimination, these are waste only in fact carbon dioxide is a waste of the metabolic reactions that occurs in the body they are eliminated by the lungs and once in the last NEET question, last year NEET question this data has been asked how much ml of gases per minute are lungs eliminate so this is super important everyone We will note this down. Ok, right? Important. Ok. Now, let's start some small small topics.
So first of all, buddies, I would like to discuss with you one word which is excretion. So what is excretion? Excretion means removal of nitrogenous waste from the body.
That means removal of removal of nitrogenous waste from the body. Waste from the body. Clear? Now what about another word which is ingestion?
Let's have a look buddies. If I say ejection, what is ejection? Anyone would like to give me answer in the comment section?
Come on, be active buddies. What is ejection? What is ejection? What is ejection? Yes, Shri Ras, come on, tell me.
Everyone, guys, please be active in the chat box. You guys are sleeping or what? Get up. Come on.
What is ejection? Egestion is removal of undigested food. Removal of undigested substances. Whatever you eat which are not digested, they will be removed from the body and process is termed as egestion.
Yes. Now, next thing is. Osmoregulation. What is osmoregulation? Osmoregulation.
What is osmoregulation? Osmoregulation means maintenance of ionic balance in the body. Ionic balance.
in the body. This is what osmoregulation is. Now we will strictly focus on the excretion procedure.
In the excretion what we have is, body is a nitrogenous waste from the body. There are various ways by which our body can eliminate the nitrogenous waste. Osmoregulation, it clear?
So this is done by, who does this? This is done by kidney. Yes, kidney helps in the process of excretion. We have a digestive tract which helps in the process of digestion and osmoregulation. Who does osmoregulation?
Who maintains it? Kdney. Kdney helps in the osmoregulation. So these are the three definitions which you should understand.
Okay? Now, as many times I am saying that there are nitrogenous waste. Nitrogenous waste come out of the body.
Now what are these nitrogenous waste? Nitrogenous waste they are of three type. So what I am discussing here is the types of nitrogenous waste. Nitrogenous, one second, one second buddies.
types of nitrogenous waste. So there are three types of nitrogenous waste. So simultaneously buddies keep writing okay.
Keep maintaining your notes. So that will be helpful okay. Types of nitrogenous waste.
So nitrogenous waste are of three different types. Let's have a look. First is ammonia.
Ammonia you all know right. Ammonia is the one which is highly toxic. This is highly toxic. Highly toxic.
This is the one which is synthesized by all types of organisms. All types of organisms. Right?
Now there are organisms who eliminate ammonia as nitrogenous waste. These organisms, they are termed as ammonotelic organisms. Ammonotelic organisms. Do we eliminate ammonia?
But I have written, you will say no. But I have written over here, they are synthesized by all type of organisms. But, Do we eliminate ammonia?
No. Then what do we do? We convert ammonia into urea and then we eliminate the urea.
Is this point clear? So next thing is it require large amount of water. It require large amount of water for amount of water for excretion. excretion right and this is the one which you can see over here this is highly toxic toxicity is highest here here the organism which show such type of elimination is here we have an example of a bony fishes we have aquatic amphibians this is shown by bony fishes you aquatic amphibians amphibians and aquatic insects aquatic insects those who live in water so they eliminate this ammonia as a nitrogenous waste we do not eliminate ammonia as a nitrogenous waste why because these organisms they live in water and when there are there is lot of water surrounding them it it become easy for them to eliminate so they require lot of water and yes along with highly toxic this is highly soluble also in water highly soluble also in water whatever example i am dealing with you i am giving you these everything is there in your ncrt and that is the reason we are here and we are discussing it okay now next thing is urea okay now let's talk about urea urea is less toxic less toxic and similarly less soluble it is soluble but less soluble they are synthesized by say there are organisms who synthesize it So what our body do is our body convert ammonia into urea. Who?
humans in humans right mammal be organisms so ammonia is converted into urea how with the help of a urea cycle here i am using the word urea cycle or krebs tensile cycle CREB hence late cycle ammonia will be converted into urea. These organisms they are termed as ureotelic organisms. We are ureotelic.
We are ureotelic organism. And how much water do we require? Less amount of water for excretion.
Less amount. of water is required for then removal so what our body do is we have a structure termed as a liver which converts the ammonia into urea with the help of a urea cycle of the Krebs-Henslitt cycle so we become ureotelic organism So this is less toxic, this is less soluble but water is, if I talk about that one, another one that is very much soluble. Here we have an example of mammals, amphibians.
So here we have an example of mammals, terrestrial amphibians. amphibian and the most important part is cartilaginous fishes cartilaginous fishes bony fishes are ammonotelic see bony fishes they are ammonotelic i'll come to this side so that you can have a clear look and if i talk about the cartilaginous fishes they are ureotelic so these are the cartilaginous fishes, bony fishes and cartilaginous fishes. So these are the marine fishes.
Moving on to the next is uric acid. So uric acid, uric acid, uric acid, uric acid. So uric acid is least toxic, least toxic.
They require very less amount of, least amount of water, least amount of water for excretion. For excretion. Least amount of water they require for excretion. Now this question comes in everyone's mind.
Do we produce uric acid? What do you suggest? Yes. Do we produce uric acid? Yes.
We do produce uric acid. yes, so those who consume lot of in fact purines in their diet, so purines for example tomato is rich in purines, the red meat, so whenever we consume purines in our diet, now this is the same purines, purines, pyrimidines, you know the DNA, this is the adenine and guanine, if you will take lot of this then what our body form, our body forms the uric acid. uric acid and uric acid crystals sometimes get deposited here that means in the joints due to which we feel pain gouty arthritis arthritis okay uric acid crystal they get deposited so we have to take care of it so they require least amount of water require least amount of water for excretion they are least toxic and if i talk about the example what comes in your mind the birds example boots right the insects right what do they eliminate they eliminate uric acid and one more thing the reptiles yes how can we forget reptiles reptiles the snails terrestrial snails so this is a way of conservation of water they conserve yes what's the doubt you have roshan tell me So this is how they conserve their water.
If you are done with biology, that's great, isn't it? You are done with whole biology. Good. Hello.
Okay. So purine, then xanthine, then into uric acid. Purines are your adenine and guanine.
So those who consume lot of purine in their diet, so that purine is converted into the uric acid crystal. And uric acid crystals, they are not good for the body. It causes various problems.
Okay. Now moving on to the next is excretory organ in various group of organism. This is the next topic.
Now I have discussed that some organism they eliminate ammonia, some organism they eliminate urea, some organism they eliminate uric acid. Okay. But there are various group of organisms. Okay.
And different group of organism definitely these nitrogenous waste because they are the product of metabolism will be produced and we have to eliminate them. So how can we eliminate them? Because they are having some specific structures. Let's start with the Porifera.
What do you think? Which structure is present? It's the simplest one.
Pore bearing organisms do not have any structure. So how do they eliminate the nitrogenous waste? They live in water.
They excrete ammonia. How? From the general body surface. Similarly in case of coelentrates, in case of tenofor, they do not have any excretory structure.
They eliminate ammonia from the body itself. Done? Point clear?
Whatever I have mentioned over here, it doesn't mean that I will be only talking about them. Because you have already done the chapter, Animal Kngdom, so hope you know about these structures. Yes, buddies, everyone?
Clear? Let me have a look. I don't know why your chat sometimes goes... Is it possible to crack? Yes, definitely.
Wow, this is definitely possible. Okay, great, great, great. Great.
Yes, yes, yes, yes. Now your chart is fine too. Okay, clear?
So, if I talk about porifera, sealantrate, coelentrata the third one I said tenophora no acid structure is present so what do they eliminate they eliminate ammonia from body surface body surface now what comes after you know tenophora platyhalminthus organ level of organization right organ level of organization starts in this Now organ level of organization starts first of all in platyhelminthus. So in case of platyhelminthus, protonephridia, flame cells, solanocytes are present. Solanocytes are present which helps in the elimination of nitrogenous waste. Here we have an example of platyhelminthus, flatworms, rotifers, some annelids, cephalopod and amphioxus. Hope a good revision is happening and everyone is enjoying.
Guys, again I am saying simultaneously keep writing. Keep making notes. Now the next thing is if I talk about the nephredia. Oh, one more phylum is left.
What is that we are left with? Ascalimithus. Yes. Yes, Nirupama. What about Ascalimithus?
What do they have? They are having rennet cells. So let's write down that also.
So if I talk about Ascalimithus, not mentioned again in NCRT this chapter. but in animal kingdom it is mentioned. They have Rennet cell, H shaped cell Rennet cells. Moving on to the next is Nephridia seen in earthworms and other annelids.
Now you know this particular topic, detailed study is not there in NEET annelids. Earlier annelids earthworm was there in detailed study I'm saying just like that of a cockroach and frog we have done in the previous session. Now If I talk about annelids, so annelids especially in earthworm, three different type of nephridia are present. Septal nephridia, pharyngeal nephridia, intergumentary nephridia.
So they help in elimination. Cockroach we have already done. So hope you remember Malpigeon tibule.
Malpigeon tibule is seen in case of insect, your favorite cockroach. Where are these present? They are present at the junction of midgut and hindgut.
Moving on to the next is antennal glands, green glands present in crustacean. Example is prawn. Yes, yes, arthropod, yes, kidneys.
Okay, what about echinoderms? Who is going to tell me about Nirupama? Tell me about echinoderm.
Nirupama, come on. Echinoderm, echinodermata. What is present in case of echinodermata? Absent?
Absolutely right. So how do they eliminate the nitrogenous waste? Because they have those...
Podia like structure from that they eliminate. So this is absent. Good job.
Very nice. Absent. Okay.
Now in various group of organisms you will find kidney. Kdney is there. So excretion is not absent.
Excretory organ is absent. They do not have a specific excretory organ. Okay. Okay my dear buddies.
Now let's move on to the main topic. That is. this chapter is all about human excretory system we keep on talking about human human human human excretory system because it is a chapter of human physiology now first thing is the position position position okay so where is this present second Now, first position. Where is this present?
This is present, kidneys are retroperitoneal. Kdneys are retroperitoneal. Retroperitoneal in position. Retroperitoneal means on one side, they are having that peritoneum layer, right? Now, the next thing is If I talk about kidney, what is the exact position in between 11th and 12th rib?
In between 11th and 12th rib. Now, next is another thing which your NCRT talks about that this is present between last thoracic. thoracic to third lumbar in between these we have is the kidney how many kidneys do we have?
we have a pair of kidneys yes we have a pair of kidneys pair of kidneys now what else you can see over here this is a diagram of a hole excretory system here not only the kidneys are present you can see some pipe here there are ureter present there is a urinary bladder and there is a urethra so pair of kidneys are there ureter again pair ureter is present in pair there is a urinary bladder a uv and there is a urethra all these structures are present and they in they act actually constitute the human excretory system. Human excretory system. Now, here you can see this is the right kidney. I will label it here.
What is this? This is the right kidney. Right one and this is the left side kidney.
Okay. Now you can see the right kidney is slightly lower. Do you know the reason? Yes, the ribosomal gland is there in the hemicoid.
Very nice. Now do you know the reason why? The reason is here we have liver. Because of liver it is slightly lower. Right one is slightly lower.
Now here these are the kidneys. Now from the region which is termed as a pelvis. Pelvis is labelled over here. Pelvis.
and from the pelvis three things are there on one side so it is like if you look at the structure structure is this is a kidney and from the kidney this is the ureter that comes down here there is a sorry I will use another color there is a renal artery which go brings in the blood brings in the blood And there is another one which I will use the blue color. There is yes there is the renal vein so what is this renal vein red one is what red one is renal artery renal artery what is the yellow one yellow one is ureter so here there is a region which is termed as pelvis So out of this, can you see this, this, you know, notch, a notch, right, something structure, this is termed as hilum. So this is termed as hilum, hilum. I'll explain you what is hilum, what is the pelvis. I know you guys must be confused between what is hilum and what is pelvis.
Okay, see, let's come here, I'll explain you. This is a kidney cross section. Now this area is termed as pelvis, this one.
Whereas the notch, notch is termed as a hilum. Done. Is this point clear to you? Now we are moving towards the kidneys.
We are talking about each and everything one by one. First, let's talk about the length. Kdneys.
Length. Length is around 10 to 12. 12 centimeter right 10 to 12 centimeter is their length to talk about the width 5 to 7 centimeter is the width and if i talk about the thickness thickness is 2 to 3 centimeter their weight is almost around 150 centimeter 150 to 170 gram. This is what their weight is. Okay, some basic basic basic data bodies I have given you. So it varies also in some organism It is 120 to 170. So it varies right 120, 150, 170. It varies from one person to another.
Now let's come to this diagram and let's see what all structures are there. Here you can see a renal capsule. Kdney covering is termed as a renal capsule made up of fibrous tissues made up of fibrous tissues fibrous tissue right capsule is present and capsule basically helps in protection kidney has two different part now outer part now can you see this outer part outer part is termed as cortex outer part is termed as cortex now towards the inner side see i'll mention it here.
So towards the inner side of this, that means towards this side, this side of this line, what they have is the medulla. What they have is the medulla. This must be mentioned here.
No, it is not mentioned. So let's mention it. This is termed as medulla.
What is this? Medulla, right? In the medulla region, you can see medullary pyramids are there.
1, 2, 3, 4, 5, 6, 7. 7 to 8 medullary pyramids are there. What are these medullary pyramids? And if you will focus on the medullary pyramid, this is how the medullary pyramids look like. See, something like this medullary pyramids are there. And in medullary pyramid, the structural functional unit of kidney that is the urinary ferroestibule that is the nephrons are present.
Now let's have a look. See, what will be present here? I am just making one diagram. Okay?
Right? So like this nephrons are present. Can you see these nephrons?
So what are these? Nephron. Let's label this as.
What are these? Nephron. Nephrons are also termed as uriniferous tubules. Uriniferous tubules are structure and functional unit of kidney.
structural and functional unit of kidney. Clear? How many such nephrons are present in each kidney?
How many nephrons are present in each kidney? So each kidney there are around 2 lakh. In fact more than that, this is much number nephrons they are present. Okay?
okay and what they do they help in the elimination of the nitrogenous waste how that I'll tell you later on now guys can you see can you see this structure now this is one the one structure which you can see over here see this is one which I have drawn what is this this is a medullary pyramid right this is one medullary pyramid so like this there are multiple medullary pyramid And in between the medullary pyramid, you can see some columns are there. Columns. And these columns, they are termed as renal column. They are termed as this column.
Right? So, these are termed as renal column. And this is renal column of Bellini.
Renal column of Bellini. Clear? Point clear? Can't see the diagram.
There is a brightness. Can reduce please. This is Dr. M. This is from your NCRT only.
Because right now I cannot change the brightness. What you can do is you can open your NCRT. You can have a look. And if you face any doubt, any problem, you can talk to me.
You can ask in the chat box. This is a renal column of Bellini. Now what is the renal column? Bellini, renal column is the part of cortex. What is this?
Let's label. What is this? This is a part of cortex, cortex present in medulla, present in medulla region, medulla region. Clear?
Done? Now, next here you can see this is one nephron opening. Right? Similarly, other nephrons they will also open over here.
Now, everything, everything, whatever you can see, they will open into one duct. Right? This is termed as duct of Bellini. Duct of Bellini. So it is like this opens into a duct which is duct of Bellini.
Now here only nephron, some thread like structures you can see they are termed as Bellini. Clear? Now here.
Now let's focus on this diagram. Now I will explain this. Now here you can see they have a structure like this.
Clear? Then they open. Right?
This is how they open. Now can you see this structure? What is this? These are the calyx region.
These are the calyx region. Calyx. And which calyx is it?
Minor calyx. This is minor calyx. Again you can come over here.
You can see in your NCID diagram this is mentioned that calyx. So there they have actually labeled the minor calyx. Done?
Minor calyx. similarly just like that of the first one there will be other structures they are also present like this now they will fuse together they will fuse together not only two three two four they will fuse together this is a minor calyx this is also minor calyx guys can you see this is also minor calyx this is also minor calyx both the minor calyx are fusing you So what we will get is this is the one which is termed as major calyx. Right. It's not a rocket science just that you have to understand. Right.
So if I talk about the medullary pyramids, suppose in our kidney medullary pyramids, there are eight. How many minor calyx will be present? Eight.
Right. Minor calyx will be eight only. Now these minor calyx, you can see minor calyx, they are fusing. and what we are getting is another calyx right ultimately everything whatever the filtration whatever the urine that comes in the region centermost region and that centermost region is labeled over here that is termed as renal pelvis that is termed as renal pelvis and after renal pelvis what is there the urine goes into the ureter urine goes into the ureter is this point clear done any doubt any doubt no so what we have learned so far is a kidney we have a pair of kidney present color is reddish she shape is uh bean shaped right and if I talk about bean shaped structure so if you look at the bean so bean is like this so this area is termed as hilum and interior to the hilum we have is a pelvis region from the hilum the ureter goes out the renal artery which supplies the blood comes in renal vein goes out done clear you some nerves are also present but which is not mentioned in your ncrt so we'll not talk about it i could have given you n number of enough of knowledge regarding this topic the reason is why we are not discussing because that is not there in your ncrt and your neat exam is all about ncrt nothing comes out of the ncrt okay otherwise i could have given you n number of things and you'll be like okay oh this is something new which we are learning today so we have to primarily focus on this one Okay, done? Where is the renal column of Bellini?
The part of calyx which is the part of, sorry, the cortex which is there in the medulla. This is the duct of Bellini. Do not be confused between Bellini and Bellini. Both are completely different. Now, moving on to the next, now let's talk about the nephron.
Right? Yes? Everybody?
Okay. So nephron you can see here. Now nephrons, they are having two different parts. First part is termed as glomerulus. Glomerulus.
Second part is termed as renal tibule. Renal tibule. Now this you must have learnt in your 9th and 10th also. But here a greater depth up to a, you know the one. till the point where the things are there in the NCRT, till that point we are discussing.
Okay. So, some basic structure which I know you guys know about it. So, glomerulus is there and there is a renal tibial present.
Done? Renal tibial is having further parts. Let us see what all parts are there.
In the renal tibial, there is a Bowman capsule. There is a Bowman's capsule. Next structure they are having is the Dct, proximal convoluted tibule.
There is a loop of Henle. Loop of Henle. There is a DCT.
And there is a collecting duct. Collecting duct. Any doubt? Now question comes in a paper. And question is like, can you tell me what is Malfeasance Carpacels?
Okay, let's write down. What is Malfeasance Carpacels? What is Malfeasance Carpacels? Malfeasance Carpacels means glomerulus plus Bowman's capsule plus Bowman capsule that is a Malfugion capsule.
Now let's look at the structure. Here you can see there is a cup like structure. This cup like structure is termed as Bowman capsule which is mentioned over here.
Next structure is a proximal convoluted tibule which is Dct. Third structure is a loop of Henle. So loop of Henle is further part. The one which descend down is descending limb of loop of Henle.
One which ascend up is ascending limb of loop of Henle. then there is distal convoluted tibial and ultimately there is a structure which is a collecting duct. Done?
Now question comes that what is glomerulus? Glomerulus is this. Can you see?
In the center, there is a tuft of capillaries in which are termed as glomerulus. Here, afferent arteriole comes in which carries the blood and efferent arteriole goes out. Now here, let's... understand the topic. What is the flow of blood?
Passage of blood. Like I have discussed earlier, the blood comes in the kidney with the help of a renal artery. Renal artery. Blood comes in.
Right? Renal artery is that artery which is having highest, highest nitrogenous waste. Right?
It is artery. So why it is coming? It will supply the oxygenated blood. So it is having oxygenated blood. Oxygenated blood.
Students confuse here. Ma'am, what is the artery? What is this arteriole?
So I am going to explain you now. Now renal artery say the blood will go further. Here it will enter into various arterioles. So renal arterioles. Arteriole.
Lot of arterioles are there. So it is like, I will explain you. See it is a one duct coming and one duct is further bifurcating into lot of arterioles like this.
This is a renal artery bifurcating into renal arteriole. Renal arteriole say blood will enter, one of the renal arteriole will enter into one nephron. one nephron, another nephron, another nephron like this there will be lot of bifurcations. Now this will go to the Bowman's capsule.
Bowman's capsule. So in the Bowman's capsule as this blood was having nitrogenous waste so there will be filtration of blood. So there will be filtration of blood.
And after that from the Bowman capsule the blood goes out to renal arteriole or afferent arteriole. I will write down. The afferent arteriole.
Clear? See. Or now it will go out. by efferent arteriole efferent arteriole yeah efferent arteriole done hope it is clear till now from efferent arteriole blood will enter into peritibular capillaries here blood will enter into peritibular capillaries Now what are these peritubular capillaries? Let's have a look.
See. Can you see this? Right?
Can you see this? It is further branching. Efferent arteriole is further branching which we call it as peritubular capillaries.
Now this peritubular capillaries, they form a network of capillaries around the loop of Henle and that is termed as the Vasa Recta. Now that from peritubular capillaries to vasorecta. Vasa.
Vasa say renal venule. From renal venule to renal vein. Renal vein. And renal vein will take the blood out of kidney. So, renal artery was full of nitrogenous waste.
Now, the renal vein will take the blood which is very less in nitrogenous waste because nitrogenous waste will be filtered in the Bowman capsule. Okay, clear everyone? Okay, now, hope this structure is clear.
Now, moving on to this, now let's talk about the Bowman capsule. All the Malfeasance body. renal capillaries, barfugin capillaries were in the same thing.
Here buddies you can see there is a afferent arteriole coming and efferent arteriole leaving. Which one is having more diameter? Which one is having more diameter?
Can you tell me? Here the efferent arteriole is arteriole which is having more diameter. On the contrary, efferent will be having less.
What is this? What is this? This is a glomerulus.
glomerulus. What will be the lining of this glomerulus? You know the fine lining, what will that be? It will be endothelium. It will because it's a capillary so it is endothelium.
Endothelium is squamous epithelium. So here in the glomerulus the simple squamous epithelium will be present. Simple squamous epithelium. simple squamous epithelium.
Now let's talk about the Bowman capsule. Now I'm talking about just the Bowman capsule. This is what? Bowman capsule.
Right? What is this? This is the parietal layer.
This is the parietal layer. Parietal layer of Bowman capsule. This is made up of squamous epithelium.
squamous epithelium. Done? If we talk about the inner layer, can you see the inner layer? So this inner layer is termed as visceral layer.
Visceral layer. Visceral layer, if you look at the visceral layer, here some special cells are present which are termed as podocyte. And I will explain you the structure of these cells, podocyte.
They create a space like structure which create a filtration slit. So what are these? These are the podocytes. You want to have a look how these podocytes look like? Okay.
Now, here the podocytes are like this. Podocytes. These whole cells are podocytes.
Podocytes. Can you see? These are the podocytes. Yes? Clear?
Now podocyte is having this structure. Can you see this process? What's the name of this process? Pedicel. Pedicel.
Now because of the pedicel, there is formation of filtration slit. What is this? Can you see this space?
And you know, this space is termed as filtration slit. Filtration slits. And because of the filtration slits, easy filtration of blood can occur. Easy filtration of blood can occur. Now tell me any doubt.
If yes, then... please let me know buddies come on come on come on come on everyone yes nirupama anyone any doubt till now no okay this is clear Now let's talk about as we have already done the structure of nephron. This is how a nephron look like.
Now let's talk about the types of nephron. Let's talk about the types of nephron. The nephron is of two different type.
Good. Is of two different type. One is cortical nephron.
Cortical nephron. And second is juxtaglomerular nephron. There is huge difference between these two.
Here, these are the neptune. This is one type of nephron. Another type of nephron is like this.
They have longer loop of handling. they have longer loop of endless. Now if you look at this nephron, this is a cortical nephron, right, juxtaglomerular nephrons are like this.
Always remember when we talk about a nephron, nephron ka the glomerulus, the Dct, the DCT and collecting duct, it is towards the cortex region. You can note this down. If I talk about the Bowman capsule, if I talk about the glomerulus, glomerulus, the Dct, the DCT, this is always towards the cortex, always in every, all the nephrons, right, but there are some nephrons who are having shorter loop of Henle, another are having longer loop of Henle, so cortical nephrons, they are 85% of the total nephron, of total nephron.
Whereas 55% of the nephrons are like this. 15% of nephrons are like this. Now, if I talk about the cortical nephron, they are having shorter loop of Henle. Loop of Henle.
Whereas these nephrons, they are having longer loop of Henle. right here in this case vasa recta you remember peritibular capillaries which form a network of tibules around the loop of henley is termed as vasa recta so here in this case vasa recta is absent vasa recta absent now here in this case vasa recta is present present In a normal condition, this one works, cortical nephron. Whereas when we talk about a condition where, you know, when there is a water scaricity, in that condition, the juxtaglomerular nephron works.
Okay? In that condition only. Okay?
Juxta and cortical. Good job. Clear? Okay.
Now, let's talk about now the passage of urine. How does urine flow? Let's have a look.
the urine flows in this direction like from the urinary ferrestibule urinary ferrestibule is nephron urinary ferrestibule is nephron you want to write urinary ferrestibule you can write you can write nephron you can write from here the duct of bellini Bellini, from duct of Bellini to minor calyx, from minor calyx to major calyx, from major calyx to the pelvis, to the ureter, to the urinary bladder. then to outside. Yeah, from urethra to outside.
Okay? So this is a flow of urine. Done? Okay buddies.
okay now let's talk about one more topic that is a juxtaglomerular apparatus so what is a juxtaglomerular apparatus let's have a quick look afferent, this is a section so I'm drawing it like this. Clear? This is how a Malfugion Carpacilis look like. Yes?
So here buddies if you look at the DCT DCT, I'm saying DCT. So DCT is present in Croh's proximity here. What is this?
This is a DCT. These are the some cells, the smooth muscle cells of the afferent arteriole. Here, let's label.
This is DCT, distal convolated fibula. What is this? What is this? Right?
Can you see? Some smooth muscles, smooth muscles of afferent arteriole. They modify muscle. They modify and what they form is JG cells.
Juxtaglomerular cells. Clear? Can you see here this cell? These cells. They are termed as macula lutea.
macula lutea. Clear? Are you getting this point? Let's have a quick look now again.
First is the JG cells. JG cells are the smooth muscle cells of afferent arteria. Some macula lutea cells. Both of them they constitute the juxtaglomerular apparatus.
Both of them. JG cells and macula lutea cells. Right? Okay?
Okay? Now here you will see the JG apparatus. Now this JG apparatus, they will release renin. They will help in the formation of erythropoietin and the calcitriol.
Now they will first release the renin. So what is the function of renin? Renin basically helps in maintaining the osmolarity.
How does it help in maintaining the osmolarity? That I will tell you later on. So what is the function? They help in maintaining the osmolarity.
Maintaining osmolarity. Clear? Now next is erythropoietin. Erythropoietin helps in the RBC formation.
It goes to the long bone and it helps in the RBC formation. Now moving on to the next is Calcitriol. Calcitriol you remember vitamin D.
This is the same. Now this Calcitriol helps in the absorption of calcium in diet from food. Calcium from food. Done?
Clear? This is JG apparatus and this is their function. Right? Both these structures they are what? They are the Malpigeon body.
Body or renal carboxyles. Malpigeon body or renal carboxyles. These are the one and the same thing. Okay?
Done? okay now we have to move on to the next topic and next next topic we have is a mechanism of urine formation mechanism of urine formation the mechanism of urine formation now you all know that we excrete around 1.5 to 1.8 liter of urine per day and depending upon the water we take in the fluid we intake so that also increases if we take more fluid in our diet so there will be more urine formation so that you all know so there is an exact process by which the urine formation occur so let's have a look Here you can see this is a structure of a nephron. So there are three steps involved in the mechanism of urine formation.
First one is glomerular filtration. Second one that is termed as reabsorption. reabsorption and third one is termed as secretion secretion now let's have a look glomerular filtration is a filtration which occurs here in the glomerulus if I talk about the reabsorption reabsorption means can you see guys some arrows coming out of the nephron so this is termed as reabsorption arrows coming out and where does these substances go you can see bicarbonate is there, NaCl, water, nutrient, K plus is there so where does it go? it goes to the peritubular capillaries because here you will see the peritubular capillaries are there and in the peritubular capillaries these substances they will go and they will enter like this, it will enter like this, done?
so every arrow not only in this Dct area you can see the area over here also some arrows they are going out Whatever the arrows they are going out, they are termed as the reabsorption. Right? Now third word is termed as secretion.
So secretion means whatever arrows you can see which are going inside. Now this is arrow going inside, this is arrow going inside, this is arrow going inside. What are these? This is secretion. Right?
Arrows going inside, these are the secretion, secretion. That means during the process of urine formation, still some substances, which are not of use to our body, they remain in the peritubular capillaries and we remove them. And how do we remove them?
With the help of secretion. So like this, now we are going to start with the first procedure which is a glomerular filtration, then the reabsorption and the secretion. Now, first of all, let's start with the glomerular filtration.
Again, I am making the same diagram, glomerular filtration. woman capsule this is efferent arteriole efferent going out clear now here you can see some blood here what happens is blood comes over here what comes over here blood Clear? Done?
How much blood comes over here? Here around 1100 to 1200 ml per minute blood come over here. This much blood comes here.
And if I talk about out of this, out of this, only the plasma part is filtered. Cells do not come in urine. Does blood cells come in urine?
RBC comes in urine. Normal condition? No, right? WBC comes in urine?
No. Flatlets comes in urine? No. So only plasma filtration occurs.
So out of this, if I talk about the plasma, the plasma you all know, that will all, out of this if I calculate, which is just 55%, if I calculate from this, that is 650 ml per minute plasma comes over here, which we have to filter. This is the plasma 650 ml per minute which comes over here which we have to filter. Now our next data suggests after the filtration out of this 650 ml you know how much comes here in Bowman capsule?
That is around 125 ml per minute. So with this data this is a filtrate formation. Filtrate rate. that is 125 ml per minute. So just imagine if this 125 ml per minute we are forming, then what will happen?
How much urine are we going to expel? That means per minute 125 ml we will be eliminating from the body. But out of this we conserve most of them. So how do we conserve most of them?
We conserve with the help of reabsorption. Now for this filtration to occur, 650 ml plasma will come over here and out of this 125 will come here and whatever comes over here that will be termed as filtrate not urine. Later on it will be reabsorbed, substances will be reabsorbed from this, something else will also be added so that will be then we can call it as a urea. So here if I talk about the filtration pressure.
So there is a glomerular filtration pressure. filtration. Can you tell me what is glomerular filtration pressure?
What is that? Filtration pressure. There is blood colloidal osmotic pressure.
There is a third one, colloidal hydrostatic pressure. 3rd one, hydrostatic pressure. These are the 3 pressures which plays a great role.
Great role. Can anyone tell me? Come on, come on, come on. Anyone who would like to tell me what is this pressure?
And how much is this Be active buddies in the chat box. Come on, come on. No?
This is 55 mm of Hg. I'll explain. This is 30 mm of Hg. This is...
15 mm of Hg. Now the pressure which this plasma create is termed as glomerular filtration pressure. Glomerular pay whatever pressure the plasma is creating is termed as glomerular filtration pressure. That is 55 mm of Hg.
Now next thing is if you will realize here some blood cells. they will come and accumulate over here which will not allow the filtration to occur. They will not allow filtration to occur. They will cover the surface.
So that is termed as blood colloid osmotic pressure which is 30 mmHg. So 55 is a pressure which exert and the 31 which doesn't allow the filtration to occur. So this is a positive pressure and this is a negative pressure. While filtration, some substances they will come over here and will accumulate over here. Those which will accumulate over here, they will exert a pressure and will not allow.
It is like, it is like buddies, you are just sieving. So you are sieving a tea. You are making a tea and during the process you sieve a tea.
What do you do is you take, you take, you know, your tea and just use a strainer. So once you start straining, at that time the pressure is really very high. So that pressure which you are you know the vessel which is there in your hand is creating that is termed as a glomerular filtration pressure just imagine after some time what will happen now these you know the tea leaves they will settle on this uh your the strainer that will be termed as a blood colloidal osmotic pressure the tea leaves similarly here the blood cells they will create that negative pressure and the third thing is if you realize that your pot you know the you know the cup where which you are filling that is already uh filled with the tea that will create a pressure at back. So this is the same.
Right? So they will create a pressure, colloid hydrostatic pressure, this is also negative. Now what is a net filtration pressure?
Net filtration pressure, what is the net filtration pressure? Net filtration pressure buddies will be 55 mm of Hg minus 30 mm of Hg minus 15 mm of Hg. So total it will be 10 mm of Hg.
Just have a close look. By the time I'll drink some water. You guys please.
Okay, okay, I'll explain you again. I'll explain this again. So it is like there is a pressure.
by which the fluid comes in and that pressure is glomerular filtration pressure. Ok Dr. M. Now next thing is what will happen some cells they will settle over here which will not allow the filtration to occur. That will create a negative pressure. That is a blood colloidal osmotic pressure.
And during the filtration some pressure will be exerted by the substances which are present in the filtrate. That will be the colloidal hydrostatic pressure. Clear? We need the PYQs but first Nirupama my point is I have to complete the syllabus.
It's not as you can see here in the title it is written that I will be talking about this chapter first. There is a one shot of zoology. Later on once we will complete the topic, once we will complete the chapter then we will do some questions.
Okay. Okay. Now moving on to the next is now let's talk about the tubular reabsorption. Tubular reabsorption means What do we mean by tibular reabsorption? That means reabsorption of substances.
Now what is this? This is let's say the Dct, proximal convoluted tibular. This is the peritibular capillary surrounding it. Peritibular capillary surrounding it. Now substances they will go like this.
Now this is termed as reabsorption. What is this? This is the reabsorption.
Reabsorption. Reabsorption. Now this reabsorption occurs in Dct, in DCT and loop of Henle.
Now let's see what all substances they are being reabsorbed. Okay, now come back to this. Here in the Dct, some substances like HCO3 negative, NaCl, water, nutrients, K plus, amino acids, I am mentioning it here, amino acid, there will be glucose, they will be reabsorbed. Should I write it? I will write it here.
I will write it here. So first let's talk about Dct. In Dct there will be reabsorption of the glucose.
Very important question is how much glucose is reabsorbed? 100%. Whatever glucose comes in the filtrate in normal condition 100% is reabsorbed back. Moving on to the next is the amino acid.
How many amino acids are reabsorbed back? 100%. Normal condition you will not find amino acids in the urine.
Next thing NACL. NACL. Next thing water.
Next thing K+. Next thing what is next next next next oh we are left with the what is left we are left with HCO3 negative. Clear?
They will also be reabsorbed back? Yes. So these are the substances.
Along with this, the creatine, the puric acid. Clear? Is this point clear to all of you? Any doubt? Okay.
Now guys, let's move back. Here if someone asks you where is the maximum reabsorption occur? So you should know the maximum reabsorption occur in the Dct. So here there is maximum reabsorption. Maximum reabsorption.
Around 70 to 80 percent. 70 to 80 percent are reabsorbed back. they are reabsorbed back.
This much substances, they are reabsorbed back. What is this? This is your Dct.
What all substances they are being reabsorbed? You can see here, here you can see there is a glucose, amino acid, NaCl, these substances they are being reabsorbed back. Okay, right? Now, one question which has been asked multiple times, ki what about the lining of this, of Dct? lining of Dct is always brush bordered cuboidal epithelium brush bordered cuboidal epithelium always remember super important this is okay now next thing is if I talk about the you know If I talk about the glucose, amino acid, NaCl, the K+, how these are being reabsorbed?
This is reabsorbed by the active absorption. Active, this is also active, this is by water, by diffusion, right? This is by active, this is also by the active reabsorption.
Whereas if I talk about the HCO3 negative and along with the Cl negative, this will be reabsorbed by the passive reabsorption. This is Dct. Now let's move on to the loop of Henle. Loop of Henle. If you look at the loop of Henle, this is how it looks like.
There is a descending limb and there is an ascending limb. Clear? So from descending limb, you will see water is coming out.
Water is coming out. From here, the NaCl is also coming out. Here also NaCl is coming out. Right? What is this?
This is a descending limb of loop of Henle. descending limb. Why do we say descending limb?
Because from Dct the filtrate goes down like this right descending limb of loop of Henle right. So if you look at their lining so they are squamous epithelium squamous epithelium. So descending limb of loop of Henle is the one which is impermeable to other substances. This is the one which is permeable to only water. So this is the one which is permeable to only water.
Water only. Clear? Whereas this is the ascending limb. Here I am writing ascending. Why do we say ascending?
Because it ascends towards upper side, ascending limb. So ascending limb is the one which is having cuboidal epithelium. Simple cuboidal. And this is the one which is impermeable to water. One which is impermeable to water.
This is impermeable to water. Here if you will see, I will show you here. Here, you will see here, now descending limb of loop of Henle only water is coming out.
Ascending limb, two arrows are there. One NaCl is here, another NaCl is here. Now this NaCl, whatever comes out from here, here there is a passive reabsorption.
So this is a passive. Below one is a passive, above one is an active. Active reabsorption.
Yes, Sadakat. What do you want me to repeat? What's the doubt?
Yes, Sadakat. Passive. Come on, tell me.
What's the doubt? No. Moving on to the next is, now one thing is here let's remove this not creatine so this I am removing it will not be reabsorbed in fact it's a secretion occur that I'll explain you at the time of secretion okay now let's talk about the third one what is that DCT Tistel Convintive Tribule, NaCl, Water and HCO3 negative comes out okay now we have to majorly talk about the DCT distal convoluted tibule. So distal convoluted tibule is that tibule where there is conditional reabsorption.
Where there is conditional reabsorption. conditional reabsorption. Conditional reabsorption that means here whatever reabsorption occur they are under some condition.
Okay. Now, so here again there is reabsorption of NACL water HCO3 negative. Clear?
Now in what circumstances does conditional reabsorption occur? Let's have a look. So here what happens is, see, whenever hypothalamus, hypothalamus, hypothalamus release a hormone.
What is that? That is a ADH, anti-diuretic hormone, anti-diuretic hormone. right they release a hormone this ADH goes to DCT goes to DCT right this is a DCT right they have some receptors they have some receptors like this on the surface now they will go this ADH will go and this ADH will bind here these are the ADH these are the ADH, anti diuretic hormone, they will go and they will bind to the surface due to which what happens is because of presence of this the NaCl comes out and the water also comes out so there is reabsorption of NaCl in water, clear?
Similarly there is one more hormone which is by adrenal gland, which is by adrenal gland, clear? Now adrenal gland secretes a hormone, right, which is aldosterone. Aldosterone.
So aldosterone it will go right, here some receptors are present, some receptors are present, they will go and bind and due to which the water will be reabsorbed. Is this point clear? So when does it occur? When does adrenal gland secrete this? When the other structures secrete this?
That I will tell you later on. Right? When I will be talking about the regulation, that time I will tell you.
Overall, 15% substances, they are being reabsorbed. How many? 15% reabsorption occur through this.
And that too buddies the conditional reabsorption. What else? The conditional reabsorption.
Is this point clear? Now, distal culminated tubule is done. Now, let's talk about the next one. The reabsorption from the tissue. Collecting duct.
So two things are being reabsorbed. There is a reabsorption of two things. One is water because here also ADH receptors are present because ADH receptors are present on CD, collecting duct.
Just like the same which they did on the DCT, they will do the same on the collecting duct also. And the second thing is urea and urea help in maintaining. osmotic gradient.
I'll show you how. Osmotic gradient. Osmotic gradient of medulla.
Of medulla. Collecting them. Okay.
Let's have a look what we have studied so far. Buddies we talked about this arrow. First we talked about the glomerulus, then we are talking about this arrow, the proximal convoluted tubule, some arrows they are coming out, from descending limb of lumbar family some arrows are coming out, from ascending one some arrows are coming out, from the distal convoluted tubule some arrows are coming out. Clear?
Yes. Okay? Sodium reabsorption also. It helps in the sodium reabsorption also. Now, moving on.
to the next that is the secretion. Now I am talking about those arrows which goes from the peritibular capillaries to the ducts that is the uriniferous tubule. So from the Dct, potassium, NH3+, H+, bile salt, oxalate, hipuric acid, drugs and toxins.
From loop of henle descending limb of loop of henle no secretion occurs. From ascending limb small amount of urea and this urea is important. Why? For maintaining the osmotic gradient that I will tell you later on.
From DCT the K+, NH3 and H+. From collecting duct H+, N the K+. So there secretion actually occurs.
And the urea also. small amount of urine. Clear? So these are the things which you have to remember as such. Now what you have to do is see everything whatever I have explained you I have explained you with the help of this diagram.
So one thing is everyone all of you either you are appearing for sorry you will be appearing definitely for your NEET examination or if you are appearing for your 11th board 11th class examination school examination this diagram is super important. Steps of urine formation I have already given you. How does everything occur? That also I have explained.
So make sure you're not skipping any step. First we have to talk about the reabsorption or sorry first we have to talk about the filtration, the moment capsule, second the reabsorption and third one is a diffusion in detail. Okay now moving on to the next procedure which is a counter current mechanism.
So what is this counter current mechanism? Let's have a look. Now let's understand the counter current mechanism like this.
Okay. Okay. Now let's talk about the counter current mechanism. You remember loop of Henle?
How did we make loop of Henle? Loop of Henle we make it like this. This was a loop of Henle right? So how does fluid flow?
Fluid flow like this. Yes? Okay? Okay. So here the outermost region is termed as cortex.
I am talking about the extracellular region, outside the region, right? In the interstitial space. Outside above there is a cortex. Then here we have is the medulla.
So in the interstitial space here right outside outside the loop of henle kidney always maintain a gradient. In the cortex the salts are in the concentration of 300 milliosmoles per liter whereas when we talk about the medulla it is 300 Here it is 300 milliosmol per liter, then the 600, then the 900, then the 1200. Let's say, let's make it 300, 400 or let's say 600. to the 900 mOsm per liter 1200 really a small parlator. So which is having more salt?
This one is having more salt or this one is having more salt? Which one is having more salt? Definitely this one is having more salt.
Here salt is more, here salt is less, here salt is more, so this is what our kidney maintains. Why does it maintain? Because we have to filter, right?
We have for the filtration process this is important. This is what our kidney maintains. Now let's look at the loop of Henle. So loop of Henle me whatever filtrate comes in that is 300 milliosmol per litre. Right.
This is what this is the concentration of our plasma 300 milliosmol per litre. This is a exact concentration and this 300 milliosmol per litre similarly the plasma is forming the filtrate so that will also be 300 milliosmol per litre. The filtrate which is entering is 300 milliosmol per litre.
Clear? Now from the descending limb of loop of Henle what comes out? The water comes out.
So if water will come out, so what will happen? There will be more salt. So 300 becomes the 600. 600 will become the 900 because more and more water is coming out. Then it will become 1200. Then 1200 it will remain over here.
Then again what will happen? From here NaCl is going out. NaCl so it will become 900 as it will go around 600 more NaCl going out here 300 more NaCl going out why let's label this because from this area water is going out water from this area water is going out water see H2O why the process of diffusion, passive process not the active one. From this area what comes out? From this area the NaCl comes out.
NaCl coming out so that is the reason the osmolarity is reducing. Can you see this is a counter current? That means flow of filtrate in both the loop of Henle, the descending one and ascending one is in opposite direction.
Done? Clear? and why this is we are maintaining so that we can have a proper filtration for the concentration of urine clear now moving on to the next is if I talk about the vasa recta vasa recta also do very much similar so this is a vasa recta a type of peritibular capillary if you see the vasa recta The flow of blood in vasa recta is opposite to that of flow of filtrate in the loop of Henle. The flow of flow is like this, opposite.
Here, see, it is coming out, here it is coming down. The one type of peritabular capillary which is adjacent to the ascending limb of loop of Henle, the flow of fluid is opposite in both the directions. So if you will see here, you know, blood is there.
So what will be the osmolarity? Osmolarity 300 milliosmol per liter. Clear? Now as NaCl is here, so what will happen? This NaCl will be transported here, some will be transported here, some will be transported here.
Why? Because we want more NaCl on lower side because here we have to maintain 1200 milliosmol per liter. We want more deep down the medulla. We want...
more NaCl deep down the medulla so it will absorb some it will absorb and it will become to 600 to 900 to 1200 see deep down the medulla the osmotic concentration is seriously very high 1200 up the water is coming out if water is coming out from the loop of Henle the water will settle here As the water will settle here, so the osmolarity will decrease. 1200 will decrease. So to maintain this, this water will enter here. See, this water will enter here in this vasa recta.
Right? As it will enter in the vasa recta, so osmolarity will reduce. It will first become 900. Then it will become 600. Then it will become...
And the one which I have drawn in the orange, this is what? This is the Loop of Henle. Loop of Henle.
Now, let's look at the Loop of Henle. So, here you will see your similarity is increasing. here osmolarity is decreasing because NaCl is going out so osmolarity will reduce so there comes a condition because here after this the next part is DCT so there because of more excretion of more you know removal of NaCl from this what happens is the osmolarity reduces to 200. Now this question can be asked in your NEET paper the only part of the nephron where osmolarity is less than blood. In normal blood, it is 300. When I am saying it is less than 300, that is 200. Where it is? This is in the DCT.
Where it is? This is in the DCT. So, yes everyone, come on, are you able to understand the concept? Yes? Clear?
Okay. Now, this is a counter current mechanism. okay now we have to discuss the regulation of kidney function regulation we have completed the how does our kidney look like then we have talked yes Akash very nice then we have talked about the you know the functions of the urinary ferrous tubule mechanism of urine formation and counter current mechanism yeah now moving on to the next is let's talk about the regulation of kidney function So in the regulation of kidney function is first I am discussing what is the role of hypothalamus. So in the role of hypothalamus first listen very carefully suppose the blood volume decreases, BP decreases, blood pressure, body fluid decreases, osmolarity increases that is more than 300 mOsmol per liter. This is what our blood maintains 300 mOsmol per liter and it goes down when?
In DCT. So in terms of more? removal of 300, more removal of NaCl from the ascending limb of loop of Henle.
So in this case what will happen? Signal will go to hypothalamus, to hypothalamus, hypothalamus. Now what will hypothalamus do? With the help of posterior pituitary hypothalamus will secrete ADH.
another name is vasopressin, what is this ADH? anti diuretic hormone, I will give you a cheat to remember this what is anti? anti means opposite, diuresis means more urine diuresis means more urine so this is the one which is opposite to more urine that means less urine because why?
because our body volume is decreasing blood volume is decreasing so we want water in the blood now in this case the signal will go to the DCT, DCT there is a conditional reabsorption and the collecting duct and from these places there will be reabsorption of there will be reabsorption of water and NaCl now what will happen because of this just imagine the blood volume Increases isn't it the blood volume will increase Yes, or no come on because the water is there so blood volume will increase Okay, now moving on to the next is one more thing Guys one more thing when there is deficiency of ADH, when there is deficiency of ADH, ADH is not there so there will be what will be the condition? More urine and that condition is termed as the diabetes insipidus. diabetes which occur because of the high glucose level in blood is diabetes mellitus but this is diabetes insipidus.
So here there will be more urine Now moving on to the next is regulation by JG cells. The JG cells you remember, the JG cells or the JG apparatus. That also plays a great role.
So these JG cells they are present where the DCT comes in contact. Whenever this DCT they come in contact with the efferent arteriole. So there is a JG apparatus.
So JG apparatus they release renin. Now this control is termed as Ras system. Very important Ras.
So what is Ras? Ras is renin, angiotensin, aldosterone system. Renin, angiotensin, aldosterone system.
So when... When does JG cell secretes run in? Let's have a look. So whenever the glomerular filtration rate decreases, the BP decreases, ionic concentration decreases.
See, who will detect this? There are some receptors present and these receptors present, remember, the smooth muscle cells and these receptors, they will check whether the GFR, glomerular filtration rate is fine or not. When it is less, when the BP is less, blood pressure is less, ionic concentration is less, then what will happen? the signal will go to the JG cells and JG cells will secrete renin. This is a renin-angiotensin-aldosterone system.
What is the function of renin? Renin will help in the conversion of you remember? Anyone?
Angiotensin-aldosterone system. So here what happens is renin helps in conversion of angiotensinojan angiotensin 1. Angiotensin 1 will convert into angiotensin 2. Now what is this angiotensin ojan? Now angiotensin ojan is the one which comes from liver.
this will be converted into angiotensin 1 angiotensin 1 will be converted into angiotensin 2 with the help of angiotensin converting enzyme converting enzyme and this angiotensin converting enzyme comes from lungs see so many organs they are involved now what is the function of angiotensin 2 angiotensin will be having following function. Now the first function is it is a vasoconstrictor, powerful vasoconstrictor. It will constrict the blood vessel so that blood pressure can increase.
It will go to the Dct and allow the reabsorption of. Here there will be reabsorption of water and NaCl and NaCl from Dct. Third thing is it will cause adrenal cortex. to release aldosterone and aldosterone will cause reabsorption of here I am writing this this will cause reabsorption of water and water and NaCl from DC you remember this we have already done right yeah this is the regulation by JG cell RAS Renin-angiotensin-aldosterone system and this is how it functions okay now let's move on to the next one next what is the next Next, now let's talk about roll-off atrial natriuretic factor or peptide. Atriuretic factor or peptide.
This is the one which is secreted by atrial valve. Secreted by atrial. Atria is what? Atria is your heart valve.
Right? And when does it secrete? Due to high blood pressure. High BP.
Now what will happen here? This will be secreted and there will be elimination of water from the DCT. It will cause the DCT to more and more remove water from the body and more and remove water from the collecting duct. And this is the one which is antagonistic to RAS.
very important atrial natriuretic factor and atrial natriuretic peptide clear now buddies let's move on to the micturation next step which is micturation now what is micturation micturation is expulsion of that means removal of urine from the body now now what is this micturation let's have a look So for the urinary bladder, if you will see the urinary bladder, here there is outer fibrous layer present. Let's see. So three layers are present. This is a urinary bladder.
What is this urinary bladder? This is a fibrous layer. Fibrous layer. Right? Clear?
Now this is the second one is a smooth muscle layer. Smooth muscle layer. Now this smooth muscle, specially they are termed as detrusor muscle. tetrasaur muscle, tetrasaur muscles.
Inner one is the transitional epithelium. You remember in the previous chapter we have done this transitional epithelium, transition innermost innermost transitional epithelium. Okay now this transitional epithelium which you can see here innermost Here some receptors are present. Some receptors.
They will detect whether the urinary bladder is completely filled or not. Transitional epithelium has a capacity that it can increase the size because they are stretchable. Here you can see two sphincters are present. One is internal sphincter. The other is the retinal sphincter.
and second is external sphincter internal sphincter is involuntary it's not under our control, it's involuntary whereas external sphincter is voluntary this is under our control whenever these stretch receptors they will sense that urine is filled they will send a signal to the central nervous system to the central nervous system and central nervous system will lead to central nervous system will lead to there are two circumstances in this case so I'll explain you this the central nervous system has two different part one is autonomous nervous system ANS and second one is SNS Right? what does SNS do? SNS basically helps in the opening and closing of the sphincter so this helps in opening of sphincter opening and closing of sphincter of internal sphincter yeah ANS has two different part one is sympathetic nervous system sympathetic and second one is parasympathetic.
Now what does this do whenever the signal goes, here signal goes to the central nervous system from central nervous system to normal cases to the parasympathetic nervous system and parasympathetic will cause the you know the contraction of urinary bladder. urinary bladder contraction urinary bladder contraction and then signal will go to the sphincter and internal sphincter will open we will exert the pressure will be exerted on external sphincter and because of the external sphincter we feel like urinating okay then we will you know when the conditions are favorable then we'll go to the washroom and we will use it this is a normal condition right what does normal condition what works the parasympathetic nervous system suppose there is conditions are not favorable you're not look we are not not able to find the washroom now in that case a sympathetic nervous system will function sympathetic number one will help in the relaxation so that more and more urine we can hold but this is the only part which is there in your syllabus that is the reason we are discussing okay okay okay center nervous system parasympathetic nervous system this one sphincter external sphincter etc and this you know this holding of urine we we can hold our urine but if i talk about kids they cannot hold their urine you know the one year age kids send the two year they cannot hold urine because with time there's a learning of the external sphincter we learn that how we can you know hold it okay so that comes with this so the last topic of this chapter is role of excretion so role of excretion also buddies we have already done right so what else we are left with let me have a look okay now let's talk about the disorders the last topic disorders then disorders first let's talk about uremia um uremia so what is uremia uremia is a condition when there is more urea in the blood kidney failure more urea in blood because kidney is not working properly kidney is non work not working properly yeah first is uremia so for the uremia what person can go for is Hemodialysis, hemo dialysis. So what is hemo dialysis?
Hemodialysis in this case the blood. We basically take blood from the you know from the body from the radial arteries specifically and we filter it outside with the help of a machine which is a hemodialyzer and with the help of hemodialysis we after dialyzing after clearing after removal of more urea from the blood, the filtered blood we again enter into the body. So this is hemodialysis.
Second one is the kidney transplantation. Kdney transplant. Ok.
Yes. Ok. Now first thing is guys hemodialysis you know.
So there is a hemodialytic unit. and in a hemodialytic unit there is a fluid, dialyzing fluid. Here cellophane membrane is there and in that cellophane membrane pipes our blood flows. So we take out blood from the body, basically the radial artery.
blood will be filtered Here there will be dialyzing fluid. What is this? Dialyzing fluid.
Dialyzing fluid concentration is very much similar to plasma except nitrogenous waste. Except nitrogenous waste. Except nitrogenous waste. Yes?
Okay, then again what will happen we will take the blood and we will do body We will transfer the blood to the body It takes a time of around two to three hours and we keep on releasing that replacing the dialysing fluid The reason is after filtration whatever the you know, the urea is there urea will come in the dialysing fluid So we keep on replacing them now next is a kidney transplantation kidney transplantation. That means a kidney will be taken from the donor and kidney will be placed here. You remember in many cases when you will be doing the kidney transplantation of your patient if you will opt for this you know career then in that case normally in many cases the original kidney the faulty kidney which a patient is having will not be removed from the body. In fact they will use another donated kidney from any you know donor and they will place it in the pelvic region that means lower to that of the original kidney position.
that means the person will be having three kidneys one kidney which is not functional and the two more kidneys they will place sorry one more kidney they will place the pelvis region and during like when the you know when they take the kidney from the donor they take you you know the ureter also so the ureter they will take and directly attach to the urinary bladder yes so in that case yes doctor i'm absolutely right whenever there is you know rejection Suppose the organ is rejected, if organ is rejected, so that is because of the cell mediated immune response. So in organ, if you know, what we do is we give immunosuppressants also, but still if new kidney doesn't function properly in the recipient organism, so the one immune response which is active is cell mediated immune response. absolutely right. So this is the kidney transplantation. Next is a renal calculi is the renal calculi.
The renal calculi means in between kidney there is a formation of calcium oxalate salt. Calcium oxalate salts. So calcium oxalate salts they cause pain, they cause huge pain in the pelvis region.
right so if this pain starts from here and goes to the back direction it causes pain and because in our case four to five mm if such stones formation occur so those stones they can easily go out of the body but if it is more than that if it is more than four to five mm because ureter diameter is just four to five mm after that we have to definitely go for a surgery or any other method where they just break it and then they next is glomerular nephritis third one nephritis so what is glomerulonephritis glomerulonephritis means there will be inflammation of the membrane the glomerular membrane because of it the filtration will not be able to occur many cases The filtration site, those slits, you remember? Let's come back to this diagram. I'll show you. See. You remember I have shown you the slits also.
Oh, where is that? Yeah. These podocytes. Sometime the size increases due to which even protein become in urine. So that is the biggest issue.
Inflammation. Glomerulonephritis. Okay.
inflammation of not whole kidney inflammation of glomerulus Okay buddies So with this we have completed the today's class What we have done so far. Let's do a quick revision Again, I'm telling you this chapter whatever information I have given you, I have given you that information by heart. See, it's the best thing that within two hours of duration you are completing everything. Isn't it great?
So whatever information I have given you, they are directly from NCRT. Each and every line buddies I have tried to explain you to make the things better for you. And because many times it happens and students they come to me and they keep on commenting, K ma'am this particular topic you haven't taught.
But I am telling you whatever there is in NCRT that is important. If you focus on other things, if you focus on... something else if you if you're like me we have to do phd in kidney so that's not possible now so after do then go for a graduation then post graduation and then you can go for the you know research career but for the neat examination we have just two books two simple books your 11th ncrt and 12th ncrt rightly kindly buddies just focus on it and that is the reason we have designed such courses such you know the 50 days need challenge for you so where what we are doing we are focusing on the content so that more and more quality content we can provide you so that within a less time duration we can give you a lot of knowledge so it's like you were here for that two two hours of duration in that two hours of duration this chapter is completing yes so what is dr m what is confusing here what you're not able to understand i'll explain you that again what is that see everything is simple so once just do one thing after this you will get the pdf Just go through them and if you face any problem, I always tell my students to comment in the comment section. Right?
So hope all of you enjoyed the session. Yes, everybody clear. So let's wind up the session what we have discussed. So let's see nitrogenous waste come here. We talked about the human excretory system, urine formation, the tubules, mechanism of concentration of filtrate, regulation, mixturation, role of other organ disorders, each and every topic which is there in NCRT we have done.
And after this, please practice more and more questions. And those questions, first thing is from your PYQs. First practice those PYQs.
And once you are done with the PYQs, then you should practice, you know, the possible questions which are there from the NCERT. Okay. Let's wind up. Have a nice day.
Today I was not able to come up with the questions. I was not able to give you some questions. But please after this session, you can Google, you can find some previous year questions.
Do practice them. and at that i can vouch here after watching this session you will be able to attempt all the 100 100 you know 100 all the questions so all the uh you know positive energies from my side take care have a nice day and all the very best for your neat examination thank you so much bye bye uh pyqs again i'm saying pyqs are not only enough because questions they are not repeated better to do some ncrt based questions also Along with the PYQs you will get an idea how such type of questions are being asked. But along with the PYQ try do the NCRT based question also.
So how you can do this? Suppose you are done with the topic which is the mechanism of urine formation. So you should always follow that book where you know topic wise questions are given. This is a topic and there are the questions related to it. Try to solve them.
and whenever you face problem guys you have a comment section you can comment over here so we'll be coming up uh i'll be meeting you again in this week we'll do one more chapter of zoology and keep coming in those classes and these classes they will be great help for you very nice thank you so much nirupama so see you buddies have a nice day take care bye bye guys good night