chapter 26 lecture 7 involves urine storage transportation and elimination urine once it's produced is going to drain through the papillary ducts into the minor calyces two or three minor calyces will fuse together to form major calyces and they unite to form the renal pelvis from the renal pelvis the urine drains into the ureters and then into the urinary bladder and then out of the body through the urethra so we have two ureters these like the kidneys are retroperitoneal they're going to transport urine from the renal pelvis to the urinary bladder the primary way primary way that they transport is using peristalsis but hydrostatic pressure also works and gravity the orders are retroperitoneal and they consist of a mucosa a muscularis and an adventitia or fibrous coat just to get back to the gravity there for a second gravity is important they found oddly enough when they sent the first astronauts into space way way back um when they were just doing the orbit of the planet and such um they never even considered what they would have to do if they had to to urinate um so the first guy that went into space actually urinated in his suit but they found that that astronauts they came up with a whole bunch of different types of ways of catching the urine while they're in space but one of the things they didn't think about was the effect of of being in zero gravity on the urinary bladder and and the urethra uh the ureters it's when the urine is in the urinary bladder being in an anti-gravity state prevents you from being able to tell that your bladder is full until it is dangerously full and it's starting to damage um damage is starting to occur the urine is starting to back up into the orders so they had to come up with a lot of different ways to deal with the altered physiology of astronauts because the effect of gravity on urination so here you can see a cross section of a ureter we have the mucosa and this remember the urinary system is one place we're going to see transitional epithelium transitional epithelium is um it can change shape it's involved in areas where there's going to be distension or stretching and it changes shape from squamous to cuboidal or columnar and back again depending on how it's stretched we have smooth muscle and then the outermost connective tissue layer all right so here you can see the orders they're about 10 to 12 inches long their diameter is about 1 to 10 millimeters again they're retroperitoneal and they enter the posterior side of the urinary bladder through the the urine is going to flow then through the ureteral openings the bladder wall compresses the arterial opening as it expands during filling and the flow again is peristalsis gravity and hydrostatic pressure in this picture we have the urinary bladder this is the pubic symphysis so the very bottom of the hip so the mucosis transitional epithelium uh because the organ has to be able to expand and um contract there's mucus there so there's a lot of mucus inside it prevents the cells from being contacted by urine remember urine urine has a ph that varies according to your diet and your body condition and so urine can be very acidic and the mucus helps to prevent the cells from being contacted by that acidic urine also by um any chemicals that may be in the urine the mucus gives it your protective layer the muscularis you have two layers longitudinal and circular in the distal one-third there's an additional longitudinal layer and then the outer layer is adventitia urinary bladder is hollow it's smooth muscle it's situated in the pelvic cavity it's right behind the pubic symphysis and in the floor of the urinary bladder small smooth triangular area called the trigone and the ureters under the ureteral openings and the urethra drains the urinary bladder from the anterior point of the triangle in urinary bladder and women sits right below the uterus so here is the urethra urinary bladder this is the vagina and then the uterus and you can understand by looking at this picture why when a woman is pregnant she has to go to the bathroom all the time as the baby gets bigger and bigger and the uterus grows inside to accommodate the baby it puts pressure on the urinary bladder and that pressure decreases the volume this is a pubic symphysis so you can see where it sits in relationship to the hips in males the urinary bladder is just anterior to the rectum okay so here we can see the urinary bladder the capacity is about 700 to 800 milliliters the trigone is this triangular shaped area we have the urethral openings at the two corners and then the internal urethral orifice is at the point of the triangle the muscle here is called the detrusor muscle it has ridges or ruge and mucosa and again the mucosa is also going to have some protection mucus protection um one thing about the urinary bladder since we're getting rid of metabolic wastes there are a number of different drugs and different chemicals that leave our body through the urine and a lot of the chemicals the carcinogens that come from cigarette smoke are going to lead the body via the urinary system when these chemicals are in the urinary bladder and they sit in there waiting to be voided uh the chemicals the carcinogens from the cigarette smoke can have an effect a carcinogenic effect on the cells in the urinary bladder and quite often smokers will develop urine bladder cancer prior to developing lung cancer because the effect of these carcinogens sitting there in the urinary bladder so there are three layers in the wall there's mucosa again transitional epithelium the mucus there muscularis is known as the detrusor muscle it's three layers of smooth muscle longitudinal circular and longitudinal there are circular smooth muscle fibers that form the internal urethral sphincter once we get to the external urethral sphincter over here this is now skeletal muscle so the internal urethral sphincter the muscle right here is involuntary here's the urethra the external urethral sphincter is voluntary this is skeletal muscle and that controls your ability to urinate and it too also has an adventitia of loose connective tissue the micturition or urination reflex is a spinal reflex there are stretch receptors in the urinary bladder that are activated when the volume is between 200 and 400 mils sends signals to the spinal cord as well as the brain in the sacral region of the spinal cord around s2s3 reflex is triggered it's a parasympathetic remember slud salivation lacrimation urination defecation and digestion the parasympathetic fibers cause relax uh contraction of the detrusor muscle and relaxation of the internal and external sphincters you have a sensation of fullness when it fills up and initiates that initiates a desire to urinate before the reflex actually occurs since we have conscious control of the external sphincter we can initiate micturition which is urination or delay micturition for a limited period of time um in infants because their nervous system is still developing they don't have the ability to limit micturition or delay micturition until they have proper myelination of different parts of their nervous system in the female the urethra is only about an inch and a half long and it's found in the orifice between the clitoris and the vagina it's transitional epithelium it changes to non-keratinized stratified squamous epithelium in males it's much longer it passes through the prostate the eurogenital diaphragm and the penis so it has three different regions to it the prostatic urethra the membranous urethra and the spongy urethra so here you can see um the positioning here's the urinary bladder and males against it's right behind the pubic symphysis and the um the urethra we have the prostatic urethra where it goes through the prostate membranous urethra where it goes through the urogenital diaphragm and then the spongy urethra that it's the length of the penis in women it's just this little bitty thing right there this is the erectile tissue of the clitoris there's a fat pad that makes up the mons pubis and here we have the vagina so it's found right in between there are other waste management systems in our body we have buffers that bind excess hydrogen ions and blood transporting wastes the liver converts a lot of toxic substances into less toxic substances the lungs excrete carbon dioxide water and heat the sweat glands also help us get rid of some metabolic wastes like urea and small quantities of salt and the gi tract is where we get rid of solid undigested foods some waste some co2 water salts and heat the goals for lecture seven are describe the anatomy and histology of the orders urinary bladder and urethra answer why women have more urinary tract infections than men do and how the mic tuition reflex is initiated and what other body systems are involved in waste management