the urinary system plays an integral role in regulating fluid balance on our body regulating our blood pressure oh i knew we should have went to the bathroom before recording this like i was saying the urinary system plays a huge role in regulating the fluids in our body regulating our body's blood pressure and blood volume regulating the ph of the acidity of our blood and lots of other things like getting rid of waste in this video we're going to focus on the anatomy of the urinary system where everything's located we'll spend a little bit of time talking about the physiology what happens in the different parts of the urinary system so let's jump to the white board and get started so let's start off with the kidneys the kidneys are going to be the main organ of the urinary system they're going to be the organ that's actually filtering things out from the blood and producing all of the urine that we make that allows us to regulate lots of things such as our blood volume our blood pressure which is super important regulating the ph or the acidity of our blood regulating the ions that are in our blood and just getting rid of things that we don't want to be in our bloodstream anymore getting rid of waste from our blood and so the kidneys are where all of that takes place the kidneys will decide what do we bring out of the blood what do we put back into the blood to make sure that our blood pressure volume ph all those things stay at normal homeostatically healthy levels now sitting just above or superior to the kidneys are the little kidney hats i mean adrenal glands which i still think look like party hats for the kidneys and the adrenal glands aren't generally considered part of the urinary system they just happen to be right on top of the kidneys so it's hard to not include them in a diagram they're part of the endocrine system they make cortisol adrenaline and other hormones that help regulate our stress response and other functions throughout the body on the other side of my diagram i'm going to draw a cross-section of a kidney that way we can see kind of inside the kidney how things are organized there we'll talk a little bit about kidney anatomy in this video now i keep saying that the kidneys filter the blood well if that's the case we have to have some blood coming into the kidney so i'm going to draw a couple arteries on here to show the blood coming into the kidneys first i have labeled the descending aorta that's going to come out of the heart and then come down and it's going to pass right by the kidneys so blood is going to be traveling down the descending aorta and two more branches that have drawn are called the common iliac arteries so i've got the left and the right common iliac artery those are going to go down into the legs and there's lots of other branches of arteries that i didn't draw on here just for simplicity's sake but one branch that we are concerned about here is going to be called the renal artery and the renal artery is going to be a branch off the aorta that goes to the kidneys basically to deliver blood to the kidneys to be filtered so as blood leaves the heart it travels down the descending aorta and some of that blood will travel through the left renal artery some will travel through the right renal artery and into the kidneys now at this point you've heard me say renal a few times one for the adrenal glands and one for the renal artery renal just means kidney and so our adrenal glands are actually named for being next to that's what add means and kidney which is what renal means so renal is the latin word for kidney we also have nephro which we'll see sometimes like a nephrologist a kidney doctor or nephron which are the functional units that actually filter out the blood in these different parts of the kidney here we'll take a little bit closer look at those in a second so renal is latin for kidney nephro is greek for kidney if you see any of those terms just know we're referring to something related to the kidneys now we have blood coming into the kidneys so we have to have blood coming out of the kidney so i'm going to draw in some veins here the main vein that we have here is the inferior vena cava which is going to bring blood back up to the heart so it can get pumped to the lungs and so forth we have the common iliac vein which are these two branches at the bottom that go into either of the two legs and so those are going to be bringing blood up to the inferior vena cava and connected to the kidneys we're going to have the renal veins the renal veins are going to take blood that's been filtered from the kidney and bring that back into the vena cava so it can circulate back up to the heart so if we look at the path of blood flow here blood will travel down the aorta through either renal artery through these smaller branches into the kidneys it'll get filtered out and then it's going to return through these renal veins back to here then to the vena cava and then back up to the heart so blood coming in blood coming out and of course we also need waste coming out or a place for the urine to go and again urine's just going to be fluid and other waste that's filtered out of the bloodstream so whenever you pee that came from your blood and it's not red because it doesn't have red blood cells in it but it's fluid from your blood so in order to collect that urine and bring it to the outside of the body we've got things called ureters the ureters are just little tubes that are going to come from the kidney and travel down to the bladder you've got one on either side one for each kidney that's collecting the urine bringing it down to the bladder all right let's take a little closer look at the kidneys here when the blood comes in through the renal arteries it's going to travel up through here and we've got two kind of regions of the kidney here the outside of the kidney is called the renal cortex anytime you see the word cortex it just means the outside so this kind of dark pink in the kidney that's all the renal cortex and speaking of cortex and the adrenal gland this outer part of this outer layer is going to be the adrenal cortex the cortex just means outer layer so the blood comes in through this part of the renal cortex called the renal column into the renal cortex here and in this light pink area which is called the renal medulla that's where the actual filtration is going to be happening the renal medulla is also often called the renal pyramids because they're sort of triangular shaped and they contain nephrons which is where filtration happens now if you look at the end of the sections of renal medulla or the renal pyramids you'll see that it connects to little yellow spaces right there those are going to be called the calyx and the calyx are going to be collecting ducts for the urine that we filtered out of the blood so the urine will travel through this yellow area collect together and then exit down through the ureter to head to the bladder anything that's not filtered out is going to travel through the blue tubes here which are going to be the renal vein and then back to the heart and of course those tubes aren't actually blue that's just to represent low oxygen blood okay so we've filtered out waste and fluid and everything those have traveled down the ureters and then now we're here at the bladder and the bladder is just going to be a collecting place for the urine so we can keep it somewhere until we're ready to get rid of it one interesting thing about the bladder is that the ureter actually connects to the bladder at the bottom it doesn't connect to the top it wraps around sort of behind and connects at the bottom of the bladder now the bladder is very stretchy it's got what we call transitional epithelium which means that the cells can change shape as the bladder stretches now leaving the bladder is one final tube called the urethra in female anatomy the urethra is going to exit out through the vulva area and the male anatomy the urethra will pass through the penis to the outside of the body now we want to be able to control when we urinate and so we're going to have a couple sphincters which will help us do that we've got the internal urethral sphincter and the external urethral sphincter and just like the anal sphincters the difference between the two is that the internal urethral sphincter is involuntarily controlled it's sort of always closed we don't have to think about it and the external urethral sphincter we can consciously control it so whenever you need to pee and you feel you need to pee but you're holding it in you're using your external urethral sphincter all right let's do a quick recap of that we have blood that'll travel down the descending aorta and some of that blood will go through the renal arteries from the renal arteries it'll branch off and go into the renal cortex and then to the renal medulla where it's going to get filtered out by nephrons into these collecting ducts down into the ureter all the blood that doesn't get filtered out and become urine is going to travel back to the heart through the renal vein and then the vena cava everything that did get filtered out which is now our urine is going to pass down the ureter into the bladder where the ureter connects at the bottom of the bladder the urine will stay in the bladder until we're ready to expel it by urinating and so then we'll relax the urethral sphincters and the urine will travel down through the urethra to the outside of the body all right so here we have a human kidney let me turn it over real quick and there's the cross section of the kidney here we can see the ureter coming out of the kidney these are going to be the calyxes or the branches they're going to collect the urine and bring that down to the ureter we also have some renal blood vessels here and you can see those branching out going to the different parts of the kidney we can follow the ureter down here to the bladder and in this model there's a catheter going up into the bladder and you can see inside the bladder it's sort of wavy like that and the bladder is going to be really stretchy like i said so that it can expand whenever it collects with urine just below the bladder we have the prostate gland so this would have been from a male patient with the prostate gland which is just below the bladder and the urethra actually travels through the prostate gland so there's a kidney ureter bladder and then the urethra will exit down from the bottom okay here we have a 3d model of the urinary system we've got the descending aorta right here the renal artery on either side we have the renal veins just coming out of the kidneys and bringing the blood back to the vena cava and up to the heart we have the adrenal gland the kidney this is going to be the ureter which is going to collect the urine and bring it down to the bladder so here's the bladder and if i open up the bladder we can see down there there's where the urethra will be and that urethra will connect to the outside of the body if i come back up to the kidney here we can see the renal pyramids which are part of the renal medulla and then the renal cortex which is going to be the outside part here where you see all those blood vessels kind of wrapping around this is going to be the calyx which is going to collect the urine so they can travel down into the ureter there and if we want to get really up close to the kidney we've got another model here this is the renal pyramids these are going to be the nephrons that i talked about you can see all the blood vessels where it comes in through the renal column to the renal cortex and then down in the rhenium medulla where the nephrons are where the blood gets filtered and becomes the urine which is collected in these calyxes and then down through the ureter all right take a minute pause the video see if you can identify all of the parts as well as all the arteries and veins that i have labeled on the diagram all right here are those labels again so you can check and see what you knew and what you still need to practice yeah bladder where's the kidney kidney the kidney's up here the kidney's right there can you point to the kidney where's the bladder good job where's the kidney good job you learned it so much