inside the kidneys we have the main structure that you see are these things called pyramids and they're shaped like an upside down pyramid with the the point or the apex of the pyramid facing downward the main sections in here are the cortex and the medulla okay so the cortex remember cortex means crust and medulla means marrow so the cortex is always going to be external to the medulla and then you have the capsule outside of the cortex so it's capsule cortex and medulla in the medulla is where it's this region in here where we find the pyramids in between the pyramids we have these columns that we found in here okay um the point of the pyramid goes into a drainage tube and the drainage tube is called the minor kalex several of these minor chalices fuse together and make major calyx and the major calluses then drain into an area called the renal pelvis renal pelvis drains into the ureter ureter goes to urinary bladder urinary bladder goes to the urethra and this is the hilum this is the area where all of the where the ureter all the blood vessels all the lymphatics all the nerves enter an exit behind the area where the the pyramids are deep to it is the area called the renal sinuses and in here you find fat also some blood vessels so the renal cortex and the pyramids constitute the parenchyma remember parenchyma is the functional tissue stroma structural so the tubes would be structural the calyces would be a structural component whereas the cortex and the pyramids would be a physical functional structure the nephron which we'll look at in bit is the functional unit of the kidney and we find these in the pyramids so parenchymas the cortex and the medulla we have about 8 to 18 of the renal pyramids and they're separated by the renal columns and the tip of the renal pyramid is called the papilla remember papilla means nipple so it's sort of nipple shaped and that's what drains into the minor calyx here you can see these uh the tops of these calyces they are it's just like a series of pipes drainage pipes that are going to drain the urine that's produced and then it flows together so ones that attach directly to the pyramids are minor calluses the areas where they come together they drain with other minor calluses are the major calluses and then we have the renal pelvis this is a better picture I like this because here you can see it in three dimensions and see that it is just drainage tubes so these again would constitute the stroma or the structural tissue when someone gets a kidney transplant they put the donor kidney they removed the donor kidney and they put the put that in the pelvis the recipient through an incision they generally do not remove the kidney that isn't working they leave that there with all the blood supply that goes to that removed kidney and that kidney if they were to remove it there's so much of a chance of having internal bleeding um having something not sutured correctly or whatever it's it's much easier to leave the kidney in unless it's cancerous but if it's just non-functional they keep it in and then they put the new kidney a little further down um generally more closer to where the urinary bladder is and connect it to the abdominal aorta the patient then has to go on immunosuppressive drugs for the rest of their life to prevent rejection as I said the kidney has a very extensive blood supply also has an extensive nerve Supply now remember the kidney is the only a major organ that only gets sympathetic stimulation no parasympathetic even though you would think of producing urine urine is in that acronym slud it's elevation lacrimation urination defecation and digestion it's a parasympathetic activity but it's controlled by the sympathetic nervous system there is no parasympathetic nerve supply to the kidney so whether or not how much urine you produce is determined by how much sympathetic stimulation you get if it's very little kidneys will be very active if it's a lot blood will be diverted elsewhere because you don't want a good portion of your blood being filtered when you need it to go to your skeletal muscle so that you can fight or flee so we have the renal artery and then the renal vein that drains it the um when you're resting about 25 percent of your cardiac output is in the renal arteries 25 of your resting cardiac output the kidney also has a number of different capillary beds that have different functions the glomerular capillaries that's where filtration is going to occur and the arteries the arterials that lead to that we have afferent and efferent arterials remember Afrin is going towards efferent is exiting and they are going to through vasoconstriction vasodilation control the rate of filtration of the blood the peritubular capillaries go around the tubules of the Nephron and are going to be there to carry away things that have been reabsorbed back into the blood and then the vasorecta surprise the nutrients to the medulla and it doesn't disrupt the osmolarity and that's really important we'll talk about that later the nerve Supply comes from the renal plexus and that again it's only sympathetic and the sympathetic vasomotor nerves are going to regulate blood flow and renal resistance by altering the diameter of the arterioles so here we see a close-up of a renal pyramid and here we have the two major types of nephrons there's a cortical nephron where most of it is up in the cortex a little bit of it dips down into the pyramid then we have the juxta medullary Nephron okay where most of it a big loop of it is down in the pyramid and a little bit of it sits Atop The Pyramid as the blood is flowing through the kidneys it goes through the renal artery then it goes through a series of arteries till it gets to the afferent arterioles then it goes to the glomerulus that capillary bed any blood that isn't being filtered goes into the efferent arterial and from there goes to the peritubular capillaries where it's going to pick up any substances that are going to be reabsorbed goes through some venules and then a series of veins till it gets to the renal vein and exits the kidney here you can see how extensive the capillary network is inside of a kidney Golds for lecture one or to list the parts of the excretory system just describe the macroscopic structure of a kidney and list parts which of these parts help form the parenchymum which help form the stroma and what our parenchymens stroma what's found in the renal sinus list the parts of the excretory system that are risk retroperitoneal Define nephratosis afferent efferent describe how the sympathetic nervous system controls kidney function and listen describe the three capillary systems found in the kidney and describe a kidney transplant