now we can have a look at the micro and out of me the micro anatomy involving the kidney or really what's known as a nephron the functional unit of the kidney is known as a nephron and nephron this is really what it all boils down to and by functional unit I mean the smallest thing that we can break the kidney down to and still retain its primary function of filtering out waste products now the nephron has two parts it's going to have something known as the renal corpuscle or puzzle and a tubular network that communicates from that renal corpuscle now the renal corpuscle is made up of two parts we have Bowman's capsule which surrounds a glomerulus and we're going to be taking a closer look at these structures but to get a frame of kind of what we're dealing with let's take a quick peek at the gross anatomy now we know that the kidney is divided into two parts a cortex and a medulla or the center region and in that medulla we find the medullary pyramids all these medullary pyramids okay when we talk about a nephron there's two types of neurons there's cortical nephrons and then there's juxta medullary nephrons just beside the medulla nephrons now a cortical methyl one is going to be out here in the cortex and it's going to stay out there in the cortex we're gonna find Bowman's capsule that surrounds a glomerulus and then this tubular network that communicates with it now with a juxta medullary nephron these nephrons are going to dive deeper into the kidney so what we just saw was a cortical nephron and what we're gonna look at now is a just imaginary nephron and with the juxta medullary natural on we're going to have the tubular Network dive deep down into the medulla before draining into a collecting duct that really runs through the medulla to the papilla right here where the urine moves into a minor and then major kayla sees into the renal pelvis and down the ureter so of these two types the cortical nephron and the juxta medullary nephron the cortical nephrons are more numerous but when we describe the anatomy and physiology of a nephron we're going to focus on the workings of this juxta medullary nephron because it has all the same features plus that long what's known as loop of Henle that allows it to illustrate the concepts of the kidney a little bit better so when we looked at the blood vessels coming to the kidney we saw that there was a renal artery that went into lobar arteries that went into segmental arteries that went into you cortical radiate arteries after becoming arcuate arteries so arcuate arteries and then cortical radiant arteries now we're going to zoom in a bit on a single nephron within [Music] this area so what I have is I have my cortex and these little brown dots are actually little Tufts of capillaries that are attached to cortical radiate arteries which came off of an argument artery five six and so we have these little glomeruli or these little Tufts of capillaries and there's about a million of them per kidney and each one of them is a part of a natural on these Tufts of capillaries called a glomerulus we have about a million per kidney so really two million in all and you get the idea but they're all over these little Tufts of capillaries in this kidney that's what gives this kind of spotted appearance to the cortex and associated with each one of those is going to be what's known as Bowman's capsule and Bowman's capsule is going to lead into a tubular network that dives down into the medulla turns back upwards and then drains into a large collecting duct now it's these collecting ducts you need to remember we're working in three dimensions here are actually what give the kidney they're kind of striated for the medullary pyramid they're striated appearance because I have another one here there so now let's just zoom in on kind of this whole idea of a natural and let's look at the parts of it okay I'm gonna turn it upright so that it just keeps it a little bit easier okay we have at this capillary network on a ferrant arterial leading hit actually what I'm gonna be drawing here we'll just start with this kind of Bowman's capsule here before we get to the tubular Network okay we have an afferent arteriole coming in to Bowman's capsule and we also have an efferent arterial leaving now notice that the efferent arterial is wider than the efferent arterial the efferent arterial is going to lead into this capillary bed and it's going to wind all throughout whereby we end up with this large what's known as a tuft of capillaries now my best illustration of this but I think you get the idea that this is just whining around until it leaves as an afferent arteriole okay or efferent arteriole let me get some labels on this is the a parent arterial art here real blood will flow through there and this is the efferent arterial blood will leave through there okay this is the glomerulus that I've just illustrated and this is the capillary bed now it's surrounded by something called Bowman's capsule now it also has some cells connective tissue cells that help anchor it we have in trachoma euler mesangial cells and these intrical mariel or mesangial cells include white blood cells that can phagocytose anything that comes through or filters through that really shouldn't be there so here are some white blood cells but it's mostly connective tissue cells that help well white blood cells are a type of connective tissue I suppose but these connective tissues cells that help hold and support this capillary hey those are intra glomerular mesangial cells and they are kind of all around and these these little areas okay these are intra glomerular within the glomerulus Mizzy angio referring to connective tissue or mesenchyme misny angio cells we also have extra glomerular nozanne geocells which kind of accumulate around this little area is there going to be some of that extra glomerular miss angio cells here an intra lemare euonymus Angela says they're okay then comes along and pac-man or Bowman's capsule or the visceral layer of the renal corpuscle bites down on this I think a pacman biting down on this and his oral cavity is made up of epithelium that surround this this capillary bed and it folds back on itself to form the outer part of his body so he bites in and I have cells that are right up against that capillary bed and then I have cells on the outside of it this is the visceral layer of Bowman's capsule this is the parietal layer or the layer that faces the body wall and anything that gets filtered out of that capillary is gonna make its way down Pacman's gullet or down through my arm if it was his esophagus he's gonna swallow those contents and those contents are going to lead to a tubular Network so from this we can kind of shrink this thing back down when we think about Bowman's capsule to pac-man and his gullet biting down on that capsule or on that glomerulus and then him swallowing its contents whatever comes out of that capillary bed and it's going to go through a tubular network that has a proximal convoluted tubule a descending thick limb a descending thin limb I'm a sending thin limb and an a sending thick limb before it becomes the distal convoluted tubules so the cells I'm about to draw are going to cover these epithelial cells or these uh blood capillary cells so here's an epithelial cell and here's another epithelial cell and here's another epithelial cell we need to remember though that this is actually in three dimensions so here's another epithelial cell and another epithelial cell kind of going off into the distance that forms this part of pac-man's gully and then it comes back up like this I have an epithelial cell and an epithelial cell an epithelial cell covering these capillaries now in three dimensions we have to remember that they're actually covering the entire surface but I'm just going to keep drawing them this way just so we can see the perimeter and an epithelial cell but really they're covering everything with these visceral layer of Bowman's capsule okay now it turns back on itself actually let me finish the visceral layer this should have been the visceral layer here should have come down like this now it's going to fold back on itself the way any kind of visceral and parietal layers do and when it folds back on itself then it forms through this area I initially was drawing the parietal layer the parietal layer so here's the parietal layer coming back and it turns back on itself so what we have is we have this area where anything that gets through the blood capillaries ends up in this space after it's been moved through the visceral layer and once it gets through that micellar this whole visceral layer we move down this tube and this tube collects the filtrate that's now filtrate okay a little bit more anatomy and that refers to this tube work let me name some of the parts of this tube so we've seen Bowman's capsule this visceral layer that surrounds these cells and then folds back on itself as a parietal layer so it surrounds the tuft of capillaries Mary drugs I didn't do a great job with the a parent and hey Baron sorry a parent and a parent we have this single cell layer thick of epithelium that surrounds it and then that epithelium folds back on itself and you can see how things can actually go after they get filtered out of the blood and make it through the visceral layer of Bowman's capsule they can go down Pacman's throat and remember this is in three dimensions okay the next Anatomy we need to talk a little bit about is this tubular Network and here we have the proximal convoluted tubules or the PCT proximal convoluted - Byul [Music] and here after the proximal convoluted tubule we have the thick limb of the loop of Henle this is a thick limb and the thin limb inland and both of these are part of the descending limb now after this filtrate makes its way around the descending thin limb of the loop of Henle now we're at the a sending limb the ascending limb of the loop of Henle and we have a thin portion and a thick portion and that thick portion of the ascending limb of the loop of Henle is going to lead into [Music] the distal convoluted tubules the distal convoluted tubule convoluted tubules sorry I'm running out of room convoluted Co n vu l conv lu u te D Co NV u L u te D convoluted okay this distal convoluted tubules into this collecting duct which collects many distal convoluted tubules so the collecting duct is going to be over here and that distal convoluted tubules of one knot Ronn drains into it and here's another distal convoluted tubules and here's a distal convoluted tubules of another nephron and another and this distal convoluted tubules is going to collect the filtrate that was produced by all these glomeruli and made their way down Pacman's through the proximal convoluted tubule the thick descending limb the thin descending limb the thin ascending limb the thick ascending limb the distal convoluted tubules into a collecting duct and these collecting ducts will all be collected at the papilla to form the urine [Music] all these collecting ducts will end up sorry all these collecting ducts will take in the filtrate from each nephron and it's going to make its way down through these collecting ducts to the papilla it collects the urine and carries it to the urinary bladder okay right here at the thick a sending or perhaps proximal convoluted tubules there's a little bit of disagreement exactly where it occurs it's probably both depending on the situation that actually passes back by Bowman's capsule we've just laid it all flat usually it passes back by here and it passes by these specialized cells the extra glomerular missing ngo cells and the ones that are right next to this distal convoluted tubules that's passing back by our special cells that help make up along with those extra glomerular mesangial cells essentially they are those cells something known as the macula densa so we have the macula densa here and the macula densa senses the contents of the tube and can regulate the filtration rate by either feeding more blood or less blood into this capillary bed one last group of cells these are going to be the specialized smooth muscle cells called granulosa cells because they have this granular appearance to these muscle cells and I'll talk more about their function another time but these are the granulosa cells okay I probably should have divided this up a little bit into a couple different videos but now we've gotten to see the names of some of these different cells of the micro anatomy of the kidney