during its filtration process and the first one is the fenestrated capillary this is our first filter okay so the blood has to try to move out of there um just like uh if you had a like a fishing net or something and you were trying to filter something through there like basketballs and and all different sort all different size balls golf balls basketballs tennis balls soccer balls footballs and some of them would go through especially the golf balls and tennis balls baseballs but the other ones wouldn't because they're too big and that's what's going to happen here and so so this is our fenestrated capillary this is our first filter and so the things that are not going to go through there would include the formed elements which are red blood cells white blood cells and platelets and or just formed elements okay sorry formed elements okay so this is our first filter and we're going to have a set of three filters and remember that filtration is size dependent so the first filter is filtering out the really big stuff formed elements now anything that gets through this first filter is going to get caught up in the second filter if it's too big and our second filter here is going to be actually let me get rid of this top thing here just put the bottom of the capillary and over here is going to be um this is our efferent arteriole let me make this so over here is our efferent arteriole and all this stuff is going right into the efferent arterial so in the case here here's our first filter and our first filter is the fenestrated the wall of the fenestrated capillary and everything goes through there except for the formed elements okay our second filter is going to be that basement membrane on the outside of the capillary and that's going to let everything through except large proteins they will not be able to fit through those filters okay so our second filter is the basement membrane our third filter is going to have even smaller holes and it's going to let everything else through except so here's our third filter everything except medium and most small proteins sometimes a small protein or two gets through and then it gets returned a different way so these are things that are not going to become part of the filtrate these are things that are going out into that efferent arterial and just moving on okay now our third filter is a an actual a form of epithelial cell that wraps around the capillary in the glomerular capillary and that third filter is made up of cells called potasites and they have little extensions called that look like little feet and that's why they're called potasites and the feet like in between the toes of the feet that's the best way to describe it are the filtration slits okay so when filtration occurs the pressure that's formed because the afferent arteriole the one that's dumping the blood into the capillary is has is more dilated than the efferent so you're putting more in than you can remove that creates pressure the pressure is going to force uh warm down it's going to force the substances through this filter system the things that can't go through though are going to be the formed elements which are the red blood cells white blood cells and platelets large proteins and most and medium and most small proteins okay so what actually gets to move through this filter system and into to become part of the filtrate so over here is going to be our filtrate water ions okay um let's see a certain wastes glucose amino acids certain drugs and the wastes could be things like urea [Music] uric acid creatinine creatinine is um so let me just break those down for you so um urea is breakdown of amino acids it's produced in the liver from the breakdown of amino acids you remove the amino group it becomes ammonia and then the liver converts it into urea which is not harmful ammonia hurts you but urea does not and then uric acid is from the breakdown of nucleic acids and uric acid you may have talked about when way back last semester when you talked about joints gout is caused by accumulated uric acid so either a person is producing too much uric acid or what is more likely the case they can't get rid of it their kidneys aren't functioning properly or they're producing um it could be they're producing too much or they can't get rid of it either one can cause a pathological situation what happens when you have a lot of uric acid that's not being removed by the kidneys is that if you've taken a chemistry class you know that when a solution gets saturated it starts to whatever it's saturated with starts to precipitate out and generally the cooler the solution gets the more precipitates out if you can keep it warm you can keep it in solution longer okay now if you think about you have this uric acid in your blood and your blood is traveling through your torso your torso is pretty warm where is it coldest when you get to your feet okay um the further away you get from the torso the colder it gets so you're that's why your toes get cold first your feet get cold before the rest of your body except maybe your nose or something if you're outside but if you're inside it like if you're trying to sleep at night your feet might get cold it's because it's your blood carries heat muscle creates heat blood carries it and blood's going to carry it throughout your body by the time it gets down that little toe it gets cold and so the number one place for the crystallization of uric acid is the big toe and these crystals lodging joints and that's what causes gout so gout is usually in the ankle the big toe sometimes in the knee but it's deposition of uric acid crystals in joints okay so if you're susceptible to gout one of the things that you can do is um make sure you're well hydrated too because then it's less likely to precipitate out okay but there's certain drugs you can take for it now creatinine is a breakdown product of creatine and you should know from last semester what creatine does creatine is is used uh we phosphorylate creatine to store that high energy bond from um atp so we can make more atp when we're at rest okay so creatinine is also a waste product so these are the types of things that are in the filtrate now as i said the glucose amino acids those are going to 100 of those should go back into um the blood at the level of the proximal convoluted tubule and then various variable amounts of other ions okay and other other things okay all right but anything and remember back when we were talking about the endocrine system and said that okay the lipid soluble we have to they have to have a transport protein and one of the things that transport protein for the lipid soluble hormones does is it allows it to stain your circulation longer why because it's not going to be filtered by the kidney if it's attached to a protein it's going to stay in your blood okay what happens um when you first start seeing proteins in your urine okay the first type first sign of kidney disease is protein in your urine and it's actually called micro albumin orea small amounts of albumin in your urine because remember albumin is our one of our major plasma proteins it's our most abundant protein and then you start seeing increasing amounts of protein and you get to the point where we say you have protein area and then you you're in well into chronic kidney disease and you better start looking for a transplant and start getting dialysis okay and think about why you would see proteins in your urine clearly there's something wrong with the filter system okay the filters have been compromised they have big holes in them perhaps and now things are going into that filtrate that we don't really have method to put back in okay there isn't really a system in our kidneys for putting proteins you know other than real small proteins that are returned through pinocytosis but for larger proteins there's really no mechanism in your kidneys to put those back into your blood and so they stay in your your urine now um people who are diabetic have high levels of glucose in their urine why because of something called the transport maximum so let me save this and go to another one