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Young's anatomy class is not to be uploaded or distributed to any social media sites or streaming sites and not to be used without permission of dr. young welcome to chapter 24 the urinary system when we're looking at the urinary system we're really looking at the kidneys and then the urinary tract which will be the tubes that lead from the kidneys all the way out of the body the kidneys are primary primarily going to be filters to filter out waste it also will keep any nutrients water that we want to hold on to while getting rid of that waste and then the tubing is gonna be the pathway out of the body now the bladder fits in there to the bladder is basically going to be the storage area for that waste that we want to remove from the body the kidney is also going to have a lot of other functions other than just removing waste it actually helps a lot with our fluid balance that plays in with our blood pressure so if our blood pressure starts to dip too low it can hold on to more fluid hold on to more water and actually increase that blood pressure and if our blood pressure starts to get too high only have too much fluid in the system we can actually just excrete the extra water and help to bring that fluid balance back normal and help to bring that blood pressure back down it's also going to play a big role in our acid-base balance so remember acids and bases are all about hydrogen ions the more hydrogen's hydrogen ions you have the more acidic you are the less hydrogen ions you have more basic or alkaline akyuu are the kidneys can actually excrete hydrogen ions if we become too acidic if we're too basic or alkalinity it can reabsorb those hydrogen ions keep them in our system and help to bring that pH back up to normal the urinary tract is going to be composed of ureters which are two blue tubes leading out of the kidneys to the bladder the bladder itself and then the urethra is of course going to be the exit out with our kidney function the big kind of word we put with it is homeostatic processes it maintains air homeostasis it helps with pH balance it helps with blood pressure it helps to make sure we stay hydrated so all those homos processes that's what the kidneys are really gonna be responsible for so we can say it helps remove metabolic waste we can say that it helps with electrolyte and fluid balance which is technically osmolarity to put a word to it helps with acid-base balance by either removing those hydrogen's and excreting them as just waste or reabsorbing them and holding on to it it's actually gonna also help with creating new red blood cells we have a hormone released by the kidneys called urethra poeta it actually stimulates our bone marrow to make new red blood cells that's something that you're gonna look at more when you get into the endocrine system especially in Physiology whenever we're looking at the kidneys they kind of look like being shapes so kidney beans our kidneys also kind of look like beans they're retroperitoneal which means the peritoneum is basically that connective tissue that surrounds the entire abdominal cavity when we say the retroperitoneal that means retro means behind so they're pushed behind that connective tissue of the abdominal cavity so they're back towards our back on the right and left hand side not part of the abdominal cavity but push there behind it our adrenal glands also sit right on top of the kidneys our adrenal glands are gonna be used in the endocrine system to basically make our steroid hormones they're relatively easy to differentiate from the kidney because they are a more granular material however they do blend in with fat that's gonna be surrounding the kidney we're gonna see the kidneys are surrounded by a ton of actual fat or adipose tissue and those adrenal glands sitting right on top and kind of sometimes blend into it but most pictures are relatively good about making them distinct and separate but in real life sometimes it's kind of hard to differentiate the actual kid the actual fat from the adrenal gland so when we take a look at a kidneys here here on the left side you can see the left and right kidney you can see those adrenal glands sitting on top of it we can see the ureters which are the tube sleeve now the kidneys going to the bladder really well and then of course Yuri throughout goes from the bladder and exits out the body so when we're just looking at the major components of the urinary system it's not that bad kidneys ureters bladder urethra when we dissect the kidney and open it up and get into those internal structures is where it gets a little bit more difficult alright now we're gonna look at the anatomy of the kidneys once we dissect it open the very outside renal fossa is a connective tissue that actually makes it retroperitoneal this is gonna push it back behind the abdominal cavity basically almost on either side of our vertebra the adipose capsule is a fat that's gonna surround the kidney it's a really good shock absorber if we hit it get hit in the back hopefully it doesn't damage the kidney because it does have all these layers around it the renal capsule is really the very first layer of the kidney this is gonna be connective tissue that's actually making the kidney it's on an individual organ so here when we look at a picture this is real simulator what a CT scan would look like kidneys are pretty easy to find because they're pushed all the way towards the back so on either side of those vertebrae the kidney show up relatively well plus they're surrounded by a lot of fat that adipose capsule surrounds the entire kidney makes it real easy to pick out you once we start to get to more the interior of the kidney we have the renal cortex the medulla and then the pelvis which we talked about the renal cortex is gonna be more towards the outside of the kidney the renal medulla medulla literally means middle and then the renal pelvis is going to be that collecting area right before we go out of the ureters when we're looking at the cortex the cortex is where most of the blood supply to the kidney goes main function of the kidney is to really filter out blood to get out waste to get out some extra electrolytes any extra water we may have in our system so it gets a pretty large blood supply overall most of those real small capillaries are gonna be found in that cortex the cortex has columns that'll actually dive down towards the center so it kind of starts on the outside and then dives down the nephrons this is a functional unit of the kidney the nephrons is really what makes our urine it decides what we're gonna reabsorb and it decides basically what we're gonna get rid of his waste these nephrons are gonna start in the cortex and then they dive down what's called the renal pyramids the pyramids are actually pyramid shaped I'm gonna show you on the picture how these all fit together and hopefully it'll start to make a little bit more sense connected to these rental pyramids there's a collection system so each pyramid has a minor calyx connected to it and then all the minor calyx ease drained into a major calyx and then all the major calyx ease drained into the renal pelvis and then the urine will go out the actual ureter so when we look at the picture here if we start on the outside of the kidney and kind of work our way in very outside we have the renal corpuscle so this is just gonna be the connective tissue layer on the very outside making that kidney the organ underneath that we have the renal cortex it's kind of the lighter pink colored area this cortex is where the nephrons and if we look at the picture on the right those nephrons are basically just little bitty tubes those nephrons star in the cortex and then they dive down through the pyramids and you can see the darker kind of round a little bit more roundish oval but still pyramid shaped objects are the pyramids so it's kind of nice of them some of them do look like actual pyramids so they actually are called what they look like each one of those pyramids is connected to a minor calyx so the little space just right below each pyramid is a minor calyx those will all drain then into a major calyx and then finally the renal pelvis is almost right in the center of the kidney and it drains out the ureter so those are gonna be the major structures within that actual kidney like I said before the kidneys get a huge blood supply so there's big left and right renal arteries branching to each kidney they get about 1/4 of our entire cardiac output so about 1/4 of all the blood coming from the heart the kidneys actually get so it can be filtered now the kidneys have a very organized arterial system going through it and you can see all the arteries listed out for you here at the bottom of the slide you don't have to memorize the pathway I just kind of wanted to show you how organized it was here now the blood supply going to the kidney within the nephron there's eight faire arterioles and efferent arterioles a ferret means going into or towards efferent means coming out of or going away from in between those you have your peritubular capillaries because so remember capillaries are exchanged basically what happens a fair arterioles delivers the blood to the nephron specifically to the glomerulus to the head of the nephron we get some exchange happening in the capillaries so waste some electrolytes water anything small enough this is like basically the filter of the nephron can get into the tubing to eventually be reabsorbed are made into urine watts leftover hopefully big things like red blood cells glucose proteins hopefully those are too large to get past the filter in the glomerulus so that gets put back into our blood supply through the efferent arteriole and we can keep using those materials that we don't want to get rid of this potentially wastes and here again you don't have to memorize this entire pathway but it actually lists out some of those smaller arterioles and their flow so I just wanted to keep that in there to kind of show you the organization of everything this is showing the vein organization so right along with the arteries we have a venule system that runs to right along with it here again nothing I want you to memorize but I just wanted you to see it here's a picture where we can see the arteries and veins both running together so when that renal artery enters into the hilum of the kidney it branches around each one of the pyramids and then kind of has small branches going up into that cortex those small little branches going up into the cortex if we look at the picture on the right with all the small tubes this is where those real small arterioles a far arterioles lead into the glomerulus which is the filter of the nephron and the efferent arterioles are actually leading out so those are the two big important parts because it's taking blood into the filter and then taking out the blood that we don't want to get rid of wait as waste of red blood cells proteins glucose big nutrients will go back into our blood supply through that efferent arteriole then those peritubular capillaries will actually lead back into that venous system and then we can recirculate everything and reuse it in our arterial system all right looking at the actual nephron a little bit closer so like I said this is the functional unit of the kidney this is really what makes the kidney the kidney as the nephron this is the part that makes the urine so we always start with the renal corpuscle which is also the glomerulus doesn't have two or three names it's not really Anatomy this one has a third name their name is Bowman's capsule so Bowman was the person that discovered it named it after himself so Bowman's capsule glomerulus renal corpuscle it's all the same thing this is the filter of the nephron the filter of the kidneys this is technically the only part of the nephron the only part of these tubes that acts as a filter everything else just reabsorbs or excrete psa's waste nothing else filters the glomerulus or renal corpuscle is the only part that filters here's a good picture to actually go through all the different parts of the nephron so there's a bunch of different tubes all connected together you need to know what each section of the tube is gonna be responsible for so the renal corpuscle look will Mary lists this is gonna be the filter connected to that is the proximal convoluted tubule that's kind of a mouthful but proximal just means closest to the glomerulus convoluted means twisty and turny and tubular means it's a tube so it's the twisty turny tube closest to the glomerulus and we're gonna go through what each parts of this tube is gonna be responsible for hearing and slides coming up then we have the nephron loop you have a decent portion and an ASA mean portion and it literally makes a nice little loop this actually dives down into the pyramids so you can see the lighter pink on top is gonna be in the cortex the darker area is gonna be in the pyramid now this can also be called the loop of Henle so if you see the loop of Henle it's the same thing as the nephron loop this turns into another twisty turny tube this is called the distal convoluted tubules this ttle cuz it's further away from the glomerulus convoluted still twisty and turny tube you'll still a tube so distal convoluted tubules this is going to lead into the collecting duct and you can see there's several little branches that looks like they've been cut multiple nephrons all lead to one collecting duct this collecting duct will then lead down to that minor calyx and major calyx within the kidney that dumps the urine into that renal pelvis that we looked at so when we look at what the different parts of that nephron are gonna do kind of talked about the glomerulus already filter filter filter within that glomerulus you have little podocytes which are little foot kind of little foot extensions that kind of reach out and what these are gonna lead to they lead to filtration slits so remember we said glomerulus is a filter you have to have little slits in it just like you pull your water through a filter and the water can go through the little holes and the bigger particles can't that's essentially what happens in this glomerulus so the glomerulus is going to filter out or keep in our system big things like red blood cells proteins big nutrients like glucose fats and it can't get past the small slits in the filter but small things like electrolytes water waste can get through it and that's what we're gonna use to make our urine so anytime you see filter just look for glomerulus if you see little Merrill Asst just look for the word filter you can't go wrong with it so here's a good picture of the glomerulus that head of that nephron and this is blown up real big for you so we got our efferent arteriole supplying blood to Google Marilyn and we have our efferent arterial where everything that was filtered out is going to go back into our system if we look to the picture on the right here you can see the little filtration slits all within this capillary bed and this is all it is it's a capillary bed we have some exchange going on so really small particles water waste electrolytes some nutrients maybe can get through those real small slits it's bigger though it can't get through them and we actually just keep it in our system proximal convoluted tubule once we get into this to real system this is all gonna be reabsorption is what we're really looking at we do find simple cuboidal cells like we talked about in beginning of class cuboidal generally makes up tubes this is the tubes that is actually going to be making up here within the proximal convoluted tubules since we do have absorption we also find some micro villi here proximal convoluted tubule reabsorbs 60 to 70 percent of everything we want to keep water electrolytes coming through there any nutrients that might have slipped past proximal convoluted tubule 60 to 70 percent of all of our absorption then we want to get to the loop of Henle so we have two different parts we have the descending limb that goes down and we're gonna have the ACE ending limb that goes up the descending limb is actually responsible responsible for reabsorbing water yeah all the way down reabsorbs water the ACE ending limb going up is going to reabsorb sodium chloride so electrolytes mainly salt as we go back up getting closer to that distal convoluted tubule the distal convoluted tubule is going to reabsorb anything we happen to miss so electrolytes that we want to reabsorb any water we want to reabsorb hormones are also going to work on this distal convoluted tubule so sometimes our body needs to hold on to something extra like extra water or extra calcium or extra salt if it needs that extra we make a hormone it works on this distal convoluted tubules and tells it to reabsorb it and hold on to it and not get rid of it as waste here at this distal convoluted tubule this is also where our acid-base balance is going to come in we can either reabsorb hydrogen ions here or we can keep it in our tubing system and excrete Emma's waste most of the time we're actually too acidic so most of the time we're just going to excrete the extra hydrogen this waste and get rid of it with our urine so here's all our different sections of our tubules all put together so remember glomerulus the head which isn't labeled here filter filled filter proximal convoluted tubule reabsorbs sixty to seventy percent of everything descending limb of your nephron loop reabsorbs water a sending limb reabsorb sodium chloride or salt distal convoluted tubule kind of Arquette's all reabsorbed any extra electrolytes or water that we haven't reabsorbed yet hormones also work here to allow us to reabsorb anything extra we want to hold on to and this is also where acid-base balance comes into play when we get to the collecting duct so whatever we're dumping in the collecting duct at this point is probably gonna be waste with the exception of water the collecting duct can actually reabsorb some more water but that's it everything else is basically your urine so this is where we start collecting that waste we're gonna get rid of and eventually send it to our other parts of the kidney like that minor calyx major calyx and then finally our renal pelvis okay so now we'll forgot our urine made once a nephron makes that urine and like I said it gets dumped in the renal pelvis now we're really getting into that urinary tract so the ureter is gonna be our first section so the ureter leads out of the kidney and down to the bladder this is made up of transitional epithelium and really all it is is a tube leading from the kidney to the bladder to transport urine that's it the bladder is just a storage area for that urine now the bladder is gonna be made of a big muscle so we do have to have that contraction to actually get enough force to get that urine out the name of that muscle is the detrusor muscle and basically that is a bladder there's really that big muscle now we do have a special area in the bladder called the Trigon I'll show you on the picture this is where the ureters come into the posterior or the back of the bladder and then this is also where the urethra is gonna start just stretch and lead out of the bladder this is a special area because on the inside of the bladder it's nice and smooth the rest of the bladder has rugae just like we saw on the stomach has those extra folds so the bladder can actually expand as it fills up with urine here if we start on the left and kind of work our way to the right with pictures on the left you can see the kidneys and you can see the ureters leading down to the bladder if we look at the picture in the middle we can see the bladder dissected open so you can see here the Yertle openings where those ureters come in behind the bladder and actually insert in to it this area kind of forms a triangle the urethra starts to form along the lines of where those ureteral openings are making the trigon of the bladder this is a smooth area of tissue where if you look at the rest of the interior of the bladder it's all kind of wavy looking those are the rue de so it can actually expand the urethra is going to lead out of the bladder now within the urethra we're gonna have to swing kurz the internal urethral sphincter and external urethral sphincter this is set up exactly like our rectum with an internal rectal or anal sphincter and external rectal Ariel's finger the internal sphincter is made up of smooth muscle the external is skeletal muscle so as that bladder begins to fill it puts pressure on the internal it closes the external closes sends the information to the brain telling you you need to go to the restroom hopefully you make it there in time then you can relax the external the internal relaxes and we can actually have urination at that point you can see here the bladder is mainly a muscle that de três or muscle so that de Trussell muscle will contract and we actually get urination that's gonna be the micturition reflex I believe it's a very last slide of this chapter coming up it looks complicated but that's all it is bladder feels up puts pressure on the internal sphincter closes you make it to the restroom relax the external sphincter and you get urination on the very right we have a cup slides where we can actually see the ureter and the bladder wall remember this is a mainly transitional epithelium but especially with the ureter we can see it makes a tube and then the bladder you can kind of see part of that empty spot in the bladder in there as well once we have that bladder fill and we start to exit out of it this is gonna be where your rethrick comes into play so the urethra is that exit actually out of the body it's gonna different slightly for male and female for male it has to pass through the prostate and it's gonna be quite a bit longer for the female it's gonna be quite a bit shorter and there's no prostate in females I'm gonna jump straight to the pictures so we can see the difference here so on the Left we have male on the right we have the female so big empty balloon right in the center that's gonna be our bladder now with the female you also have the uterus that sits right on top of the bladder so be careful don't confuse the uterus with the bladder uterus is where babies grow bladders what we fill up with urine so if we look on the left with the male we can see that your wreath Row is gonna have to go through the prostate this is usually called the prostatic urethra then it exits out of that prostate and this is also gonna play double duty in the male with the reproductive system or ejaculatory duct or seminal duct is going to be located within the this prostatic area and it actually has a connection right to that urethra so that way not only does it serve as an exit for urine it also serves as an exit for sperm as we travel down we have to make our way down through the penis and that's where the urethra is gonna exit if we look at the female there is no prostate gland no penis so that your wreath Rhett is actually quite a bit shorter this is one reason why we tend to see more urinary tract infections or bladder infections and females and we do males and males with that longer urethra that bacteria usually gets flushed out by urine before it can make its way up into the bladder for females it's a lot shorter so that bacteria can make it up to the bladder a whole lot faster and actually stabilize itself on the bladder before it always gets washed out by the urine however we do see problems with males especially with a prostate as they age we see what's called BPH benign prostatic hypertrophy which basically means a prostate becomes larger in size it can actually make that urethral tube smaller and smaller so when metals start to age they have to get up at especially at night time to use the restroom more often and that's when they notice it because they can't get a full night's sleep so smaller amounts of urine have to come out and increase pressure in the bladder has to be actually made to get the urine to eject out females you have the uterus setting on top so that means if the baby's growing the uterus it kind of has a built-in soccer ball to come kick with that bladder so there's benefits and and problems that we see with both males and females micturition reflex so this is that urination proxy process micturition means to urinate this is what we looked at with the internal sphincter and external sphincter so when you look at it in picture form and look at how neurons run it looks a little bit more complicated but really it's not bladder fills up with urine puts pressure on internal sphincter closes which closes the external sends the information up to the brain brain says hello bladders getting full we need to make it to the restroom you make it to the restroom you relax the external sphincter which relaxes an internal that--did trestle muscle of the bladder squeezes down and we actually get urination so that's why that make tuition reflexes you