6 lecture one is Introduction to the urinary system and urinary system Anatomy urinary system is pretty simple in terms of the um macroanatomy there's two kidneys two yers one urinary bladder and one urethra gets a little more complicated when we look at the histology though uh urine is excreted from each kidney through the uriner stored temporarily in the urinary bladder and then it's expelled through the rra branch of medicine that deals with uh function diseases of male and female urinary systems and male reproductive system is nephrology and um the branch of surgery related to it is called Urology so here we have the two kidneys notice at the right kidney sits lower than the left that's because of displacement because the liver is so large they ret peronal meaning they're found in in the posterior part of the perianal cavity the two ERS connect to the urinary bladder which sits right behind the pubic symphysis and then you have the urethra in women it's just for um releasing urine in men the urra also serves the second purpose as transporting semen the job of the urinary system is to filter the blood and remove wastes mostly metabolic waste so we're talking about parts of molecules that have been have been broken down um by the liver and other organs and then to get rid of the waste and return most of the water and most of the solutes back to the bloodstream here you can see the posterior View and you can see how the kidneys sit right up against those floating ribs provide a little bit of protection and the yers are also retr paranal they go right along the iliac crest pass right by the iliac crest and this is the position of the drenal glands or the suprarenal glands they sit at top each kidney and again the right is lower than the left they have a very rich blood supply uh because their main job is to filter the blood so as I said the um job function of the kidney uh conserving eliminating water kidney uh Works along with the blood and several other systems to keep your blood volume constant it does so by causing causing more water to go into the urine producing more dilute urine or more water to um stay in the body producing darker or more concentrated urine it also regulates the ions in our blood um getting rid of some when we have too much keeping some when we don't have enough it helps to regulate blood pH through getting rid of either hydrogen ions or bicarbonate producing more bicarbon it uh the osmolarity and also glucose and regulates blood pressure rinin is a hormone that's secreted by the kidneys that aids in blood pressure regulation and it also can by itself um adjust the resistance of the blood coming into the kidney thereby um adjusting the filtration rate other things it does it releases the hormone Ropo which you know is the hormone that um causes more red blood cells to be produced also calcitriol which is the active form of Vitamin D it we secrete wastes and foreign substances through the urine conserve valuable nutrients eliminate organic waste products products synthesized CIT triol and that goes along with parathyroid hormone it acts on the kidneys and it also assists the liver and detoxification so if we're talking about the um external anatomy of the kidney there's a capsule on the outside um the uh kidney like the lungs has one opening through which all the blood vessels lymphatic and nerves enter and exit and that's called the Hillis the three layers of tissue around each kidney the one that's directly on the outside of the kidney is the renal capsule then there's a layer of fat because like the heart the kidney likes to preferentially use fat for energy and then there's an outermost layer called the renal fascia people who are extremely thin don't have a lot of fat around their kidney and so the kidneys can move they're more mobile than they are in people that have fat around the kidney and this can cause the orders to Kink and that can block urine flow and it can be a dangerous condition okay so the kidneys are kidney being shaped um they are about four to 5 Ines long and about 2 to three inches wide you can think of them in humans as being about the size of a pack of playing cards they're found just above the waist between the peritoneum and the posterior wall of the abdomen as I said they're retr peritoneal along with the ERS and they have a little bit of protection by the those floating ribs the 11th and 12th ribs if we do a transverse section through a a person and look up we'll see here is a liver you can see how much space that takes up and because the right and left kidney are being cut at different levels they look different okay um and here is L2 uh the second lumbar vertebra you can see the abdominal aorta the inferior vnea okay um so here you can see the layers as well so this tiny pink layer here is the renal capsule then we have the layer fat around it that's the adapost capsule and then outermost we have the renal fascia which is the connective tissue and holds it in place this is yet another view showing the different capsules this white area here is the renal capsule then the adapost capsule and then the renal fascia around that and you'll see there's even more fat around this area