the kidneys are not so bad you might even like learning about the kidneys even the physiology portion but if you don't have to basics down on how the kidneys work you will feel overwhelmed quickly so in this interlude we'll just do this very basic introduction to kidney function and we'll start with remembering that the kidneys are full of blood vessels that branch and branch and branch until the blood has arrived up in the cortex of the kidney and the structure hiding up in there in fact 1 million of these structures per kidney is the nephron and you'll recall the nephron is made of a little body a little ball called a corpuscle and then all everything else you see here is a tube you'll now if someone says what did the kidneys do you could say there are little structures in there called nephrons that filter the blood that's totally fine if someone says how do the kidneys work if someone wants any more detail than that what you really want to do is tell them that they filter blood but really the kidneys when they filter blood it's more than just filtering I mean imagine that you are trying to do a little bit of drip coffee and you're pouring some hot water through the grounds and through a filter if a whole bunch of those dirty grounds end up in your coffee and then a whole bunch of this water and so pour it all over the countertop then that's more like what the kidneys do in other words stuff ends up where you don't want it to like the grounds end up in the coffee pot now if you want coffee you got to go in and remove the grounds that's why your kidneys do and the hot water well that gets poured out in the wrong places too if you want it to get where it's supposed to go in the coffee pot then you got more work to do and the kidneys have to do all that work so the kidneys start by filtering blood but stuff ends up in all the wrong places so there has to be more to it but it does start with filtration so let's look at this basic diagram what we've got here is blood arriving in the renal corpuscle and filtration occurs when I say filtration occurs I mean large items will be trapped in the capillaries red blood cells white blood cells may be some big plasma proteins they're not going to leave the blood the waste like urea uric acid those waste products they can definitely leave the blood the problem is this filter is just filtering stuff out based by size based on size big stuff can't get out little stuff can so along with the little waste products come the little water molecules and the little salts and the little sugar molecules and all of this good stuff passes through the filter and is now in a tube the renewal renal tubules which will eventually pour out into the renal pelvis and the ureter and bladder and urethra in other words you've got a bunch of good stuff mixed in with the bad stuff Oh kidneys what are you gonna do so now we need a couple more steps for the kidneys to recapture that good stuff step 2 reabsorption think about this those sugars and salts and water you absorb that from your food and drink and your intestines well now you lost it so you have to reabsorb it so step 2 shows us that there's some good stuff here that we don't want to lose we have to get it back into the blood so because of this inefficient filtration process we now must reabsorb all the good stuff that was lost so downstream which is not a technical turn but I'm saying a not a technical term I'm saying later on these little capillaries hang out near the renal tubules and as the good stuff exits the renal tubules it goes back into the blood back into the reabsorption is back into the blood remember this stuff was in the blood till that crappy filter let it all out so reabsorption it brings it back into the blood the third and final step you will find this hard to believe as leaky as that filter was letting out all kinds of good stuff it still didn't let out a lot of the bad stuff the blood still has a lot of waste products in it so step three is due to the fact that surprisingly the overzealous filtration process missed some of the wastes we can pump some of those wastes out of the blood and into this renal tubules and while reabsorption occurs meaning while the tubes and the blood vessels are all hanging out next to each other that's not only a good time to reabsorb good stuff but you can also pump out bad stuff these capillaries right here they still have bad stuff in them they still have metabolic wastes so now's a convenient time as long as your reabsorbing good stuff to secrete out bad stuff into the renal tubules pretty simple but go through it go through it again and find someone that you can explain it to just do it walk through it and look up some YouTube videos until you can get those basic processes down because in the last video we're gonna name like 50 different parts of the renal corpuscle and renal tubules and talk about exactly how they do filtration reabsorption and secretion