hi everybody and welcome back today we're going to be looking at ultra filtration in the kidney if you are new here don't forget to like and subscribe because every week i will be posting a new video on a different topic so let's get into it ultra filtration ultra filtration is essentially our body's way of removing both useful and waste products and this might sound counterproductive like why would you want to take out the useful stuff essentially we take the useful stuff out because we have to regulate the useful stuff we have to regulate if we have too much of it or too little and of course in terms of wastes we need to regulate our waste we need to remove as much as possible and so in ultra filtration we actually do both at the same time now it's important for us to identify the location of ultrafiltration before we go any further so that we know exactly where this is all taking place and ultra filtration specifically occurs in this structure over here at the beginning of our nephron which is called the malpigian body it is made up of two components one is the glomerulus which is this capillary network that we see over here and the other is this bowman's capsule together they filter out all of your blood and they take out useful and waste products and they create a substance called filtrate which is a liquid that liquid then makes its way down the whole length of the nephron and as we'll learn in some follow-up videos different sections of this nephron will then absorb or exchange useful and waste products as we go along now to have a better understanding of ultrafiltration we're going to have to look at the structure of the male pigeon body and how it enables it to do its function now we've zoomed in on the malfudium body structure we need to break it down into its two main components and we're going to look at exactly how these components allow ultra filtration to occur as best as possible and how we maintain this filtration constantly so the first major component of the malfunction body is the glomerulus and the glomerulus is made up of this network as we can see here of blood capillaries that increase the surface area and essentially allow a large amount of blood to pass through and to be filtered a component of the glomerulus is of course the arterials that flow into the glomerulus now the arterial that goes into the glomerulus is called the afferent afferent means in and the part of the arterial that leaves is called the efferent the exiting now you will notice that they have been drawn in different sizes and this is really important because the sizes of the tubes of the blood vessels determine the blood pressure that's moving through the glomerulus and we always want to keep a high blood pressure in order to maintain something called hydrostatic pressure which is essentially the pressure that is exerted on the walls of the blood vessels via the liquid moving through them in other words we always really want a high pressure of blood flowing through the malfunctioning body so we can filter out as much as possible and so in order to do that we have a afferent arterial that is actually quite short and wide and we can see that here that the opening of the afferent arterial is wide and you can see even over here the diameter is much wider if you look at the efferent on the other hand you will notice it's much more narrower across its diameter and smaller and the reason for that is we are trying to take a lot of liquid and we're going to try and squeeze it through a smaller space and this squeezing action allows us to maintain blood pressure and it also facilitates enforcing particles that we want to get out of the blood into the bowman's capsule and then into the filtrate now that then brings me to of course bowman's capsule this is the capsule that sits around the glomerulus and this is where eventually our filtrate is going to collect and so getting back to our afferent efferent arterioles these blood vessels where the blood comes in in the afferent are going to squeeze the blood from a large area squeeze it down into a smaller area and in doing so it forces any of the particles that are um being needed to removed out of the blood it gets forced into bowman's capsule and then bowman's capsule does the final filtering now what does the melphigian body have that assists it along with the afferent and efferent arterials um infiltration well we're going to look at a closer picture of the glomerulus and bowman's capsule so you can see once products go into the glomerulus how do they actually move through the wall of the glomerulus and then into bowman's capsule ultimately what does ultrafiltration look like if we get really close to the tissues so now what we've done in this photograph here is we've zoomed up really really really close to the edge of the glomerulus as well as the bowman's capsule so as you can see here it says endothelium this endothelium represents the thin lining of the globalist the thin thin capillary lining the green layer on the other side here it says apodocyte now podocytes are specialized cells that are in the bowman's capsule and so what you have is you actually have two filtration layers so first of all the endothelium over here in the pink that is going to be where our capillaries are so as you can see here's our blood and remember our blood is filled with substances that are useful but also wastes and we're trying to filter those out hence the name ultra filtration so what happens is because the blood is coming at such a high pressure because of it being transported from the afferent to the efferent arterial squeezing remember try to squeeze as much through as possible what you find is a sieving action now if you think of what a sieve is it's where you take flour and you or sugar and you basically pass it through a fine mesh to get out all um the big particles and all the smaller particles can move through and that's exactly how ultra filtration works the only difference is that we're actually going to sieve the substance or the blood twice and if you are lucky enough to make it through both spaces then you become a part of what we call the filtrate so essentially this is how the movement of our blood goes it enters into the glomerulus and the first thing it needs to do is it must make its way through what we call a pore this is a pore that is in the walls of the endothelium these small little holes and if you are a particle that is small enough to move through that space then you've luckily made it through the first layer the second layer you have to make it through and you have to be small enough is these podocyte slits this is a part of the bowman's capsule if you are lucky enough to make it through both of these holes and both of these spaces you are now part of the filtering a good way to think of what exactly is the filtrate is to imagine it being a somewhat clear liquid that has a lot of useful substances in it but it also has a lot of wastes in it it actually essentially is blood without the red blood cells in it and we're going to now look at what substances can actually make it through there through the filtration and what can't make it through the filtration so let's look at the substances that are able um to make it through so the following substances are going to be able to make it through our filtrate they are things like urea salts glucose and amino acids they are small enough to fit through both the pores in the endothelium and the podocytes they can make it through both filtration points hence the name ultra filtration and they then make it into the filtrate now if you look at that list there are some useful substances such as glucose and amino acids there is also wastes like urea and salts to some degree salt is also a useful product but we're going to learn in another video how do we actually regulate salt now all the substances that remain in the blood are too big to leave and they can't actually fit through these small spaces that have been provided by the endothelium and the podocytes and these are substances like red blood cells platelets and large blood plasma proteins they're basically really big clumpy globular proteins that can't fit through these spaces and that's a good thing because you should never have red blood cells in your filtrate if you do that means you'll have eventually blood in your urine it's at this point i want to make it very clear also that filtrate is not urine yet it only changes its name right at the very end of the process when we're all the way at the distal convoluted tubule so to finally summarize essentially ultrafiltration is when the blood moves at a high pressure into the glomerulus we select out specific substances that are small enough to move through the endothelium pores and the podocytes of bowman's capsule and those substances are either wastes or useful substances and they become a part of the filtrate all the larger substances like red blood cells and platelets cannot enter into the filtrate because they're too big they cannot go through the filtration process and they remain in the blood and they leave via the efferent arterial as always i like to finish off our lessons doing a terminology recap in order to make sure that we're very familiar with the words that we have learned because learning these words is what enable us to answer these questions as quickly and easily as possible in exams so first we looked at the malpigian body which was a structure where filtration occurs and the malpiguan body is made up of two components the first component is the glomerulus which is a dense network of capillaries that intertwine with one another and it is there to increase the surface area so that filtration occurs faster and it has an afferent and efferent arterial which i'll get to now in our terminology list essentially that is what brings our blood into the glomerus and then what leaves out of the glomerulus we then have bowman's capsule which is the structure that the glomerulus sits inside of and this is the final component that we need for ultra filtration blood must move through the glomerulus then through bowman's capsule and once it's done so then it has been ultra filtered now earlier i spoke about these arterials with the glomerulus and that's the afferent arterial which is the artery that goes into the glomerulus and the efferent arterial is the arterial that goes out of the glomerulus now why are they so important these two arterials well their widths are different the afferent arterial is wider than the efferent why is this important because it maintains hydrostatic pressure essentially hydrostatic pressure is the forces exerted on the walls of the blood vessels to maintain your blood pressure blood pressure is really important in maintaining your overall physical health and cardiovascular health and to do that we have to try and squeeze blood from the afferent arterial which is much wider if we did a cross-section through it compared to the efferent which is much more narrow and the difference in the opening width improves the pressure then we spoke about podocytes and podocytes are these unique cells that we find lining bowman's capsule and they assist in ultrafiltration um in that they have something called a slit within them it's basically a thin opening which allows only certain substances to move through and so if you are lucky enough to move through both the glomerulus and bowman's capsules potocytes you now become a part of the liquid called filtrate filtrate is the liquid that we produce after ultrafiltration it's important to note that it is not urine it will only become urine at a later stage this filtrate is also going to be looked at at a later video as well and i'll unpack exactly what do we do with it after an ultra filtration and that's it for today everybody i hope that this has been a helpful video and if you liked it make sure to like the video subscribe i will keep you updated with as many exam and study tips as possible but i'll see you all again very soon bye