today's video is sponsored by keeps find the link in the description below when i was a little kid i used to have this fear that my bladder would explode if i held my pee in for too long and i remember that my big sisters one day decided to exploit this and lock me out of the house when i desperately needed to pee so there i was pounding on the door super viciously screaming at them to be let in but of course they didn't because they're big sisters but luckily for me my bladder did not explode instead i just aggressively peed my pants on the front porch but it begs the question was i just being an irrational seven year old or is it actually possible for your bladder to rupture in today's video we're going to use the cadavers to take a look at the urinary system to answer that very question so if you haven't used the restroom lately now might be a good time to do so let's do this let's start off by taking a look at the urinary system and discussing some of the basic functions of the organs and structures inside of it so here we have a kidney that's been cut in the frontal or coronal plane meaning that it's just been divided into front and back portions now the kidneys job is to filter your blood as well as adjust hydration levels so this outer rim of the kidney that i'm tracing with the probe here is called the renal cortex and this is going to be filled to the brim with tiny little filtration units that will filter the blood and drop waste into these darkened portions here called renal pyramids these renal pyramids will then transport the waste with water which we now call urine into the actual urinary tract which is going to begin in this area here and then it's going to transport that urine down this really long tube called the ureter now this is going to transport that urine to the urinary bladder and we can see a urinary bladder right here that's what this is right here so you're looking at a cross section of a female pelvis we can see the pubic bone you can see the vaginal canal right there you can see the uterus but this structure here is going to be the urinary bladder that has been cut in the mid-sagittal plane now the bladder is going to be a storage organ for urine obviously and it can store at maximum around one liter of urine but that's at maximum normally most people around four to five hundred milliliters which is around two or so cups of urine at that level that's when you're like you know maybe i should probably go ahead and urinate but do remember that one liter maximum capacity because that'll be important later but it's also important to understand that the urinary bladder is a convenience organ meaning you don't actually need to have a urinary bladder and some more many creatures on this planet don't they simply produce urine and then the urine leaves their body but the reason why most people think we have a urinary bladder is to help mark our territory so we can pee on things and say hey this is mine or this is my space or i've been here or this is a warning you're entering my territory so you'll save up all this urine and then you can expel it as you choose but you can also do it at the right time and that's going to be important also coming up later but the bladder will then have another extension coming off of it called the urethra now we can't see that in this cross section here but you can kind of picture that there would be this short muscular tube coming off of the bladder now how short depends on whether you're a male or a female females are obviously going to have shorter urethra than a male would but this is simply going to evacuate or empty the bladder so it's going to take that urine and it's going to leave the body speaking of leaving the body you may have noticed that the hair on the top of my head is leaving my body look i was in denial about my hair loss for years i can't tell you how many times i would defend myself when my friends would make jokes about my receding hairline by saying that no i just have a really high forehead but eventually you see enough pictures of yourself that you can't really do that anymore and you just have to start accepting the fact that you are losing your hair but here's the thing it doesn't have to be that way all of the time for everyone and that's why i'm excited about the sponsor of today's video keeps keeps is a subscription service devoted to helping men keep their hair they do this through clinically proven treatments with most customers seeing results around six months or so after starting treatment these treatment plans are affordable and they're delivered straight to your door the fact is two out of three men will experience hair loss by the time they're 35 years old which is why if you're starting to see those early signs of hair loss now is the best time to jump on this and take advantage of these doctor recommended treatment plans without ever having to visit a doctor's office or a pharmacy plus you'll even get refill reminders so you'll never run out of the products you need to take care of your hair hair loss stops with keeps to get 50 off your first order visit keeps.com anatomy or you just click the link in the description below that's k-e-e-p-s dot com slash anatomy all right let's get back to it let's start by discussing what's called the mcturition reflex now that's a big word but micturition just means the desire to urinate so we go back to this mid-sagittal section of the pelvis again this right here is that urinary bladder the inside lining of the bladder itself as well as other aspects of the urinary tract there's a specialized type of epithelium called transitional epithelium now the reason it's called transitional is because depending on how much urine is inside of the bladder and urinary tract it will stretch and transition to different thicknesses so less urine it's thicker more urine it's more flat and stretched out thus transitional epithelium next we have the muscle of the bladder itself this is called detrusor muscle that's its name but it's really just a type of smooth muscle now smooth muscle is involuntary meaning you are not in charge of when this muscle here contracts instead that is going to be reflexive now we can't see the urethra coming off of here but the urethra is going to have two sphincters which are just really thick and tight muscular rings the first sphincter is called the internal urethral sphincter and again this is involuntary you're not in charge of contracting or relaxing this sphincter we'll see why that's important in a moment but you are in charge of the more distal sphincter called the external urethral sphincter this one's made of skeletal muscle which means you can decide when it contracts and when it relaxes but what you need to understand is that inside of this detrusor muscle there are stretch receptor neurons and what they're doing is they are monitoring how much urine is filling inside of the bladder and what they're going to do is send that signal so they're going to send their signal up the spinal cord and that spinal cord will then send a motor neuron back or a signal back to the detrusor muscle telling it to contract that's right so once you reach about around like i think it's 200 milliliters or so of urine what's gonna happen is those stretch receptors will send a neuron and they'll get another neuron and signal back saying contract and that's also going to tell that internal urethral sphincter to relax so this is that initial urge to pee right when you're like oh i got i got a p here what's happening is the bladder is actually contracting and the first sphincter is opening letting urine down but you are in charge of that external urethral sphincter and that's because at the exact same time signals are going up the spinal cord they're going to this region of the brain stem here called the pons inside of the pons there's something called the pontine micturition center and the signal is going to go to that pmc as well as go to higher areas of the brain specifically this medial prefrontal cortex in this area here and what's going to happen is you are able to decide hey this is not a good time to urinate i mean think about it imagine you're in like a you're at a social gathering right you're among friends if you didn't have control of that external urethral sphincter well your body would just start urinating on your own and you'd just be pee in your pants so that the decision to keep it contracted comes from the cerebral cortex up here right you can actually make the decision what you have to understand though is the pmc and the cerebral cortex are working together to kind of not only figure out how or when we should be peeing but how to actually do it because when you decide to pee then the signal is going to go back down that same pathway and it's going to be reflexive again it's going to cause this detrusor muscle to contract that internal urethral sphincter to open and now the external urethral sphincter will also open and this creates a pressure gradient and the urine is going to then be released so knowing all this is it possible for the bladder to rupture or explode and the short answer is yes the long answer is it's very unlikely to happen simply from you holding your urine unless you had something else already wrong with the bladder so let's look at this if the bladder ruptures there are two different types of bladder ruptures if it ruptures into this space here into the pelvic cavity this is called the peritoneal space if it ruptures say on the top of the bladder here then goes in here we call that an intraperitoneal rupture in this event the urine will be reabsorbed by the body which will then kind of cause havoc and chaos with your bloodstream because it's the urine is literally being reabsorbed into it but it's also going to require surgery to close off that rupture but if it ruptures at another point let's say deeper down in this tissue here we call that an extra peritoneal rupture and this is actually easier to manage because you can just administer a catheter and drain out the urine from that space but you may be asking well how does this happen though right if if if if i'm saying that there needed to be something else wrong with the bladder well most cases of bladder ruptures happen due to this bone here this is the pubic bone and if this breaks due to some kind of trauma that can cause ruptures to the bladder and the most common cause of those ruptures are going to be automobile accidents picture the steering wheel hitting your pelvis hitting the pubic bone and then it ruptures some aspect of the bladder but other things that can happen are like bladder cancer right if you have bladder cancer that can weaken the wall of the bladder and then it makes it more likely for a bladder rupture to occur uh vaginal birth simply putting the child through there there have been instances where that has actually caused a bladder rupture to occur maybe someone is administering a catheter to you right they're gonna drain the bladder and they don't do it correctly and they cause an injury those are all pre-existing conditions or some kind of trauma event that is weakening the bladder which is causing that to occur the bladder rupture to occur simply you holding your urine is it's really not all that likely i mean i looked in preparation for this video i was looking at the published literature looking for case studies of spontaneous bladder ruptures and finding them without some kind of pre-existing condition i couldn't find any that were really reliable if it was more just mysterious is in we saw this happen we saw this individual they this happened to them but when you trace back their history it does seem like they had some kind of inciting event something else happened to their bladder at some other point the reason why this is so unlikely is because as that bladder is reaching that maximum capacity of one liter it makes far more sense for the urine to go up the ureters to go head towards the kidney and that can and does happen that can create urinary tract infections kidney infections you can send you into kidney failure you can actually die from urine going back up the kidneys but a far more likely result instead of your bladder just rupturing is exactly what happened to seven-year-old justin when your external urethral sphincter just opens and you aggressively pee your pants see that makes more sense from a body's perspective right like would you rather have the bladder rupture and urine go into this body cavity or into the tissues or would you just rather pee your pants and suffer a little bit of humiliation again both are not ideal but i'm pretty sure i know which one i would choose thanks again to the sponsor of today's video keeps be sure to click the link in the description below or just visit keeps.com anatomy and get 50 off your first order today as always be sure to like comment subscribe if you 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