oops we have two arterioles remember arterioles are small arteries and one of them is the afferent and that is going to go to a little knot of capillary called the glomerulus now remember when we looked at the adrenal gland there was a zona glomerulosa okay so when you think of glomerulus you can think of kidney so the glomerulus is a little knot of capillaries like knot is what i'm talking about that kind of knot and then over here we're going to have the efferent arteriole now notice that i made the afferent arterial greater diameter than the efferent i did that for a reason because it is a greater diameter than that that's one of the ways you tell them apart okay because sometimes in some pictures the afrin will be upward here where i've shown the the uh the efferent will be up where i'm showing the afferent and the efferent the efferent will be down where the efferent is and the only real way you know where which one is which there's two ways number one okay let me move this a second here make that look a little nicer number one is the diameter most times most books most pictures will definitely show a difference in the size of the arterials so this is the afferent here the other thing is if they don't have a difference in size they should at least have arrows and they may have both showing the direction of blood flow okay so the afrin arterioles are going to be bigger in diameter than the efferent now the glomerulus has a structure around the outside of it called the glomerular capsule another name for it is bowman's capsule and the glomerulus plus bowman's capsule equals the renal corpuscle okay um all right so now the next thing that we have here in the nephron is this twisted little sequence called the proximal convoluted that means twisted tubule and it's abbreviated the pct proximal convoluted tubule and then we have the loop of henley it's also can be called the nephron loop and this is the descending arm or limb of the l o h and this is the ascending limb of the loh ascending limb also has a thick an area where it's thick okay and again there should be arrows showing the direction of fluid flow okay and then we have the dct or the distal convoluted tubule and the collecting dot now different a bunch of different nephrons that are going to drain into the same collecting dot so this is the collecting duct okay and the collecting duct is going to end a little point there the papillary duct oops and that's at the renal papilla remember at the end bottom of each pyramid so if you have here's your pyramid you have that papilla and then that's going to go to the minor calyx major calyx renal pelvis and then you order your it's too far out to the side to the order to the bladder okay so blood's going to be filtered over here it's going to come in through the afferent duct at the afrin arteriole i cannot get this to look the way i want it to look tonight for some reason and i know it doesn't really matter that much but and then the blood is going to leave through the efferent arteriole and the reason there is a difference in size is because that puts pressure and that aids in filtration remember that um when we're looking at filtration and reabsorption when we're looking at bulk flow at a capillary the greater the hydrostatic pressure was the more fluid is going to move into the the interstitium in terms of that scenario here the wider the afferent arteriole is in comparison to the the diameter of the efferent arterial the more force there's going to be to force fluid in out through that glomerulus into this tubule system okay so let's talk about what happens at the the kidney and actually i'm going to erase this here so i have more room and i'm going to erase that okay okay so we are going to have three different processes that happen we're gonna have filtration infiltration is the removal of fluid so roots wastes from the blood into the tubule system so it's like renal filtration just to be specific then we're going to have re-absorption okay so filtration before going further filtration happens at the only at the glomerulus so here you can think of it things as leaving blood and it said the glomerulus only okay now um this efferent arteriole then is going to actually go around and i'm just going to do this and then i'll we'll erase it but going all around here remember we had three different types of capillaries we had the glomerulus and that's where filtration occurs that's part of a nephron and then we have the peritubular capillaries okay peri means around so it's around the tubules all right tubular capillaries that's number one number two is the peritubular capillaries and these are going to be used for reabsorption and secretion so things that have to be reabsorbed or things that we've filtered out that are good we're filtering out like anything of a certain size filtration is size dependent so it doesn't matter if it's good if it's bad if we need it if we don't if it's of a certain size it's going to be filtered now we have to look at the things we filtered and decide wait a minute wait a minute wait a minute there's glucose here there's amino acids here there's lots of good stuff here and we got to put that back into the blood okay so filtration is also size dependent let me put it up here size dependent okay so filtration reabsorption is putting good stuff back into the blood good stuff back into the blood from the filtrate because as soon as the blood's been filtered and it's in it's in here it's filtrate once it's in here collecting duct now it's urine but as long as it's in that tubule system we call it filtrate once we dump it into the collecting duct now it's urine okay so we're going to put the good stuff back into the blood um that we've filtered out and we do it by um like oops i'm going to do it into the blood blood vessels that are going around we're going to put the stuff back in okay put the good stuff back then the final final thing here is secretion