hello everyone I hope absolutely today we are going to start chapter number 27 from Guyton physiology chapter glomerular filtration renal blood flow and their control renal physiological a second chapter here previous chapter may we have already discussed the functional anatomy of the kidney so today we are going to talk about filtration uh this here is the bombing capsule or your nephron start Aura there is an afferent arteriole which is coming towards the Bowman capsule or it is and then the blood goes away by the afferent arterialism this filtration is called glomerular filtration therefore glomerular filtration glomerular filtration is the first step in the urine formation it's an important Point your information the blood gets out from not the blood actually you know components of the plasma it gets out and it is filtered from the glomerular capillaries into the bombing capsules this is the first step in the urine formation remember um a large amount of fluid through the glomerular capillaries come into the bombing capsule or kitna large amount about 180 liters per day foreign [Applause] [Applause] the most of this filtrate is reabsorbed leaving only about one liter of fluid to be excreted each day 180 liters one liter per day is the amount of urine that you actually pee out which you actually excrete okay the high rate of glomerular filtration depends on a high rate of kidney blood flow as well as their special properties of glomerular capillary membranes in this chapter we will discuss the physical forces that determine the glomerular filtration rate as well as the physiological mechanisms that regulate GFR and renal blood flow 180 liters per day factors they are important okay so that's going to be a very important chapter your information which is glomerular filtration which do not filter and then there are things which easily filter for example water water easily filters for example sodium sodium easily filters glucose glucose easily filters these are the things which can easily filter okay so there are things which can filter there are things which cannot filter okay obviously bloodkey composition different Hoagie or yeah like most capillaries the global capillaries are relatively impermeable to proteins so the filtered fluid is essentially protein free in a protein filter okay and also divide of cellular components such as the red blood cells the concentrations of other constituents of glomerular filtrate including most salts organic molecules are actually similar to the concentrations of the plasma only the cells don't come and the proteins don't come yeah important okay exceptions to this generalization include a few low molecular weight substances such as calcium and fatty acids because they are some of them actually are bound to the plasma protein is your proteins okay now for example almost half of the plasma calcium and most of the fatty acids are bound to the proteins and these bound proteins portions of proteins are not filtered so they are not filtered okay filtration rate is about 20 of the renal plasma every important headings so pay attention to this similar to other capillaries glomerular capillaries filter fluid at a rate that is determined by the following the balance of hydrostatic pressure and colloid osmotic pressure which are acting across the capillary membrane and then there is a capillary coefficient which is the product of permeability and filtering surface area of the capillaries but an important Point suppose this is a capillary okay so suppose this is the bombing capsule filter they will be filtered according to a mechanism they try to pull the substances to remain within the capillary they don't push the substances but they pull the substances it is largely because of the protein so basically there are two pressures in a capillary one is forcing the thing out of the capillary the other one is forcing things to remain into the opposite direction if hydrostatic pressure is more things will be filtered if oncoric pressure is more things will remain in the capillary pressures okay so that's the common common uh basic stuff now the glomerular capillaries have much higher rate of filtration than most other capillaries in the body because of a higher glomerular hydrostatic pressure and a large coefficient fraction for uh filtration so the coefficient is the filtration coefficient and also the hydrostatic pressure within the capillary is very high so think about it but a simple conceptual stuff okay we have a tuft of capillaries is capillary gender blood hair or is blood may cause pressure here the pressure which is pushing things out into the bomb and capsule this pressure is known as hydrostatic pressure or your hydrostatic pressure capillaries because it's more it pushes things into the Bowman capsule Factor coefficient we both it's about 180 liters per day so it's actually a big amount of filtration in the average adult human the GFR GFR government filtration rate is filtration rate it is about 125 ml per minute which equals to 180 liters per day 125 ml per minute 24 hours so that equation 125 into 16 to 24 will give you an answer of 180 liters per day 180 liters filtrate Banta the fraction of the renal plasma flow that is filtered is about 0.2 this is 20 is also filtered okay so that's a big big big fraction of the passing blood so this is what is written here glomerular filtration rate is about 20 of the renal plasma flow fraction um which is the GFR divided by the renal plasma flow or plasma blood flow ratio here that is known as filtration fraction in a normal healthy person it is 20 okay 20 of the total blood flowing through the kidney will be filtered now we have to talk about a very important topic which is the gloomarular capillary membrane abuse glomerular capillary membrane it has some specific characteristics so we have a lot of capillaries throughout the body but yeah different so this is the capillary these are special cells and they are they are actually epithelial cells so there is endothelium which is inside the capillary then there is a basement membrane cells which are epithelial cells and they are called podocytes so a thin layers that's a unique structure there are two layers there is a basement membrane and then there is an epithelial layer which is called protocyte there was a very nice diagram this one so this is the bombing capsule or a perinephrons this is the afferent arterial blood RI and this is the efferent arterial blood Jara and all this is the glomerular capillary Network capillaries so look here so that's a very important diagram for developing your concept which is epithelium the cells are also known as podocytes here layer number one layer number two and layer number three uh in the capillaries of the glomerulus and these photos are actually very very important because now together these three layers make up the filtration barrier which despite being three layers filters several hundred times as much water as the solutes filtration capacity although there are three layers 180 liters of filtrate is produced per day okay reason hey because there are structural modifications available so for example Joe endothelial lining here and these pores are called fenestrations and then you also see within the protocytes there are slit spaces spaces so there are spaces dismissive filtration easily okay it's not a jam packed system so the high filtration rate across the glomerular capillary membrane is due partly to its special characteristics the epithelium is perforated and they have fenestra so age of perforations these perforations are the finished foreign membrane is negative so when we see the basement membrane is a negative charge uh entity it's either photocytes have a negative charge this is an endothelium protein molecules protein molecules so if any molecule is a positive charge molecule it may still pass ligand proteins are basically negatively charged molecules cannot pass so protein is negatively charged limited protein molecules okay that's the basic basic concept also have negative charges and they repel the proteins and do not allow the proteins to filter so all this paragraph is very well clear now filterability of solutes inversely related to their size it's a very easy heading to understand is that's what is written here filter ability your ability to filter of solutes is inversely religious the larger the size the lesser the filtration capacity easy stuff is membrane is thicker than most other capillaries but it is also much more porous systems that's the simple story this is what is written all in here now a filter ability degree of 1 means the substance is filtered as freely as water whereas a filter ability of 0.75 means the substance is filtered 75 percent as rapidly as water so albumin albumin is protein so albumin filter ability zero because so if you look at this table here water key filter ability is molecular weights sodium molecular weight water says filter ability equal to water hair glucose almost equal to water release 0.75 75 percent of the myoglobin yeah the better way of putting that would be a myoglobin keto filterable capacity comparison only 75 percent okay alumin is a protein energy filter ability closed captioning not available the positive charge will actually easily pass so the molecular diameter of the plasma protein is about only six nanometers whereas the pores of the glomerular membranes are eight nanometers because of the negative charge or negative charge is because of a lot of proteoglycans so you put out your capillary system it is negatively charged um which shows how electrical charges affect the filtration of different molecules dextran are polysatrides that can be manufactured as neutral molecules or with negative or positive charges note that for any given molecular radius positive charge molecules are filtered much more readily in comparison into the negative charge yeah it's a two axis graph here we have x-axis and here we have y axis okay now x axis and y axis may have so which terms represent x-axis is representing uh radius radius of the substance so as you go towards the right the radius of substance is increasing okay I'm talking about this data point to this point per uh radius on the x-axis so it's about 22. slightly more than 38 so radius you will read on the x-axis like in relative filterability in a filter this is how the graph is labeled filterability 0.6 here is 18 okay let me ask you what is the radius the radius your size it is around 22 and what do you think is the filterability the filterability is just below 0.8 so filterability you read on y-axis and size you read on x-axis this is how you read the graph observation through technical things as the size is increasing now listen to this carefully molecules and then we have a molecule which is an ionic dextron so let's look at if in the polycat ionic dextron we are increasing the size so this is the increase in size increasing the size as you are moving in this direction on the x-axis you are increasing the size increase so if on this point I ask you what is the size size is 34 what is the filter ability filterability is 0.6 is size is 42 or filter ability so here the size is 42 and the filterability is around 0.2 yeah 0.27 is 34 or filterability 0.6 So Yesterday reduce so that has an inverse relationship is suppose for example we are talking about this particular data point is data point per what is the size the size is on x exit so it's about 22 and what is the filter ability around 0.2 the size now is 30 and the filter ability is almost close to zero so 22 says so filter ability reduces with the matter of size size so let's for example take this data point is data point per or AC data point is molecules so this is the data point that we are talking about is data points size is about 30 okay or is data point per is black Valley Line 30 because we are taking this data point so x axis so it's around point eight point eight seconds but anyways let's take it point eight like it is almost close to zero zero reason this is negatively charged molecules which means this is positively charged molecule so same size per size same size k is that clear now so that line should not be clear that note for any given molecular radius positively charged molecules are filtered much more readily than negatively charged molecules the reason for these differences in filterability is that the negatively charges of the basement membrane of capillaries obviously and porosides provide an important means of restricting large negative molecules including the plasma protein now they are talking about a disease which is called minimal change nephropathy and increase glomerular permeability to plasma proteins normally plasma proteins they become more permeable to plasma proteins there are changes in the food processes of the photocytes even though they may look normal when viewed in the standard light microscope higher magnification per year electron microscope they usually displays may become something like this you know you see the difference here they are flat here they are indented so they become flat protocytes and this is called podocide effacement the causes of minimal change nephropathy are unclear but it is believed that this is because of the T-cell secretion of cytokines and this is perhaps a sort of autoimmune attack or attacked on protocyte due to any other reason feed processes and they become straight this increased permeability permits protein to be filtered by the glomerular capillaries and excreted in the urine condition which is called protein urea or albumin urea albumin minimal change nephropathy is most common in young children but also can be seen in adults just made there are three layers filtration difference and number two is the negative charge of all this apparatus disease so far so good now let's start talking about determinants of the glomerular filtrate also look at this diagram for example your filtration the process an important role in the production of glomerular filtration rate the GFR is determined by variable factors for example the sum of hydrostatic and colloid osmotic forces across the glomerular membrane which gives the net filtration pressure terminology this terminology is extremely important to understand okay what is the net filtration pressure details that is the net filtration pressure number one number two is the coefficient filtration coefficient filtration coefficient hair that will also have an impact on how fast or slow the GFR will be details obviously but if we first have a look at this diagram and try to understand 4 four forces which are actually working in this region here we are looking at the afferent artery this is the glomerular capillary organization so this is the efferent arteriole and this is the Bowman capsule filtration the filtration will be in this direction that is from the glomerular capillary to the bombing capsule is filtration facility there are total four forces of char forces and the term is hydrostatic pressure hydrostatic pressure basically for the sake of understanding the hydrostatic pressure means hydrostatic pressure it will push things in the opposite direction see what is this this is glomerular capillary so is anything in the plasma away from the capillary away from the capillary Muslim head towards the bombing capsule horses so hydrostatic pressure pushes things in the opposite direction hydrostatic pressures safe glomerulous meaning capsules it will push things from the bombing capsule to the capillary so the the term hydrostatic pressure simply means it is a pressure which pushes things in the opposite direction number one hydrostatic pressure of the glomerular capillary hydrostatic pressure of the bombing capsule so hydrostatic pressure of the glomerulus capillary hydrostatic pressure here of the bombing capsule is going to be safe pressure only the pressure but that actually is the hydrostatic pressure so much pressure hydrostatic pressure that is known as hydrostatic pressure yeah p g so this pressure is basically the PG pressure okay then the next pressure is the hydrostatic pressure of the bombing capsule so hydrostatic pressure in the bombing capsule is represented by PB so a pressure is [Music] it favors filtration you know it does not favor filtration it rather stop filtration your filtration these are the hydrostatic pressure it favors it opposes they are basically because of the protein molecules right this is the global capillary is glomerular capillary proteins this is called oncotic pressure either it is called oncotic pressure or it is also called colloid osmotic pressure same thing so osmotic pressure capillary cosmotic pressure is the osmotic pressure of the glomerular capillary and it is represented by pi symbol and G Pi is for osmotic pressure and G is for glomerulus it is a favoring filtration yeah it is opposing filtration so it is opposing filtration protein capsules there is a category which favors filtration and there is a category which oppose filtration hydrostatic pressure of glomerulus opposed Carnival pressure hydrostatic pressure of bombing capsule favorite osmotic pressure of the bombing capsules it is actually practically is equal to zero it is effectively zero okay so technically speaking factors hydrostatic pressure of the capillary hydrostatic share of the bombing capsule and osmotic pressure of the glomerulus there are only three pressures listed hydrostatic pressure of the capillary hydrostatic pressure of the bombing capsule and osmotic pressure of the capillary in teen factors may say yavala factor a factor or a factor though factors that is the hydrostatic pressure of the capillaries minus sign K so net filtration pressure calculator it is the you know equation which is listed here okay up hydrostatic pressure mathematical equations forces so both these forces they oppose uh filtration equations hydrostatic pressure which is going in this direction or capillary cosmotic pressure so capillary osmotic pressure hydrostatic pressure with a minus sign and this is then Oriental values so uh hydrostatic pressure just force say filtration from the capillary to the bombing capsule is usually 60 minus bombing capsule hydrostatic pressure it is 18 with a minus sign minus sign Matlab it is opposing filtration and the osmotic pressure of the capillary it is also opposing filtration so that's also the minus sign and then you calculate this whatever happens is the 10 millimeters of mercury so net filtration pressure that is 10 millimeters of mercury yeah okay so now you have the concept of net filtration pressure up net filtration pressure value usually 10 years coefficient of filtration you get the GFR gfrk glomerular filtration rate is the net filtration pressure represent the sum of hydrostatic pressure and colloid osmotic pressure that favor uh opposite filtration and the forces include HR forces you now know this okay now GFR can therefore be expressed as a coefficient of filtration multiplied by this now what this is this means the net filtration pressure so net filtration equation coefficient fraction coefficient fraction multiplied by net filtration pressure or net filtration pressure actually which opposes filtration okay hydrostatic pressure in the capillary so it favors uh filtration positive sign what was PB PB was the hydrostatic pressure in the bombing capsule negative sign because it opposes filtration and this is the osmotic pressure within the capillary negative sign this is the osmotic pressure within the Bowman capsule positive sign but practically it is zero because bombing capsule proteins or negative sign okay values if you calculate all this uh the net filtration pressure is 10 mL meters okay very clear majority of the life for renal physiology is going to be cool because the important Concepts I told you okay what is the uh you know hydrostatic pressure in the glomerul capillary I told you what is the hydrostatic pressure in the bombing capsule I told you what is the osmotic pressure in the glomerular capillary and then the osmotic pressure in the bombing capsules plus sign hydrostatic pressure in the capillary favor hydrostatic pressure in the bombing capsule hydrostatic pressure goes in the opposite direction so it opposes filtration this opposes filtration this opposes filtration this favors filtration forces increased glomerular capillary filtration coefficient increases the glomerular filtration rate fraction net filtration fractions on the filtration coefficient the filtration coefficient is a measure of the product of the hydraulic conductivity and the surface of the glomerular capillaries which means basically or total surface area the filtration coefficient cannot be measured directly but can be estimated experimentally by dividing the GFR uh by the net filtration pressure so this is the same equation which is roaming around here and there yeah so this equation GFR is equal to filtration coefficient multiplied but not foreign so the next equation we'll get is the GFR divided by the net filtration pressure because the total GFR for both the kidney is about 125 milliliters per minute or we for the sake of Simplicity call it 120 millimeters per minute and then the net filtration pressure it was about 10 millimeters the normal KF is about 12.5 milliliters per minute so that's a simple calculation 120 net filtration pressure so if you just divide them you get about 12 milliliters per minute and when the filtration coefficient is expressed per 100 grams of the kidney weight the average is about 4.2 milliliters per minute so 120 MLS per minute because the filtration coefficient is so so high or you highest capitalism there are photo sites available okay although the increase filtration coefficient raises the GFR and decrease filtration coefficient reduces the GFR changes in the filtration coefficient are probably not very well understood and that all makes sense hydrostatic pressure decrease glomerular filtration rate is slowing it is decreasing filtration is so this is what an example of increased bombing capsule hydrostatic pressure and decreased GFR direct measurement of hydrostatic pressure in the bombing capsule and at different points of the proximal tubule in the experimental animals using micro pipettes have made us you know able to calculate K humans but that's an extrapolation increase in the hydrostatic pressure in the bombing capsule will how does that work okay so this is all good in certain pathological State associated with obstruction of the UT Unity track bobbin capsule pressure will increase or the bombing pressure increase that's a very very sensible thing to understand okay that is increased glomerular capillary colloid osmotic pressure is foreign osmotic pressure number one the arterial plasma colloid osmotic pressure and number two is the fraction of the plasma which is filtered by the glomerular capillary so that's an important thing increasing the colloid osmotic pressure raises the glomerul capillary colloid osmotic pressure which in turn decrease the GFR increasing the filtration fracture also quantum concentrates the plasma protein and raises the the colloidosmolic pressure okay and maybe GFR your head that will go down for example a reduction in the renal plasma flow consequently even with a constant GFR hydrostatic pressure a greater rate of the blood flow I'm parking this so park this information because so if the protein amount is increased this pressure will increase they will just feel like be more because gfrs protein concentrated so that actually makes all sense a year heading B should make sense to you increase Global capillary hydrostatic pressure a glomerular capillary hydrostatic pressure contextualize any pressure within the capillary Direction it is in the flavor of filtration yes therefore a positive sign will also increase glomerular capillary hydrostatic pressure increases the GFR simple the global capillary hydration pressure has been estimated to be 60 changes in the globular hydrostatic pressure serve as the primary mean for physiological regulation of GFR increase in the hydrostatic pressure raises the GFR whereas decrease in the algebra District pressure in the glomerulus obviously red reduces the GFR glomerular hydrostatic pressure is determined by three variables each one of which is under physiological control variable arterial pressure resistance or thesis increase in the arterial pressure tends to raise the glomerular hydrostatic pressure and therefore increase the GFR however as discussed later in this chapter there is autonomic regulation like in Pella points there are horses for so many different reasons our blood pressure can increase so if we have high blood pressure hypertension what will happen reduces the hydrostatic pressure and decreases the GFR conversely the dilatation does the opposite thing again this is very very uh logical um it is this is all very very sensible now once you understand it with Concept you will not be stuck Factor number three constriction of the efferent arteriole if the efferent arterial is constricted there is increase resistance to the flow as a result there is rays in the hydrostatic pressure and too much increase in the GFR so things is foreign foreign [Music] levels of constriction there is a slight increase in the GFR but with severe constriction there is a decrease in the GFR yes the primary cause of the eventual decrease in the GFR is as follows as effluent construction becomes severe and as plasma protein concentration increases there is a rapid non-linear increase in the osmotic pressure caused by the dominant effect the higher protein concentration then ultimately reduces the GFR okay to summarize constriction of the afferent arterial reduces gfratulations however the effect on the efferent arterial is dual dual camera and again this is very logical it makes sense should be easily understood there is slowing of the blood evacuation or hydrostatic pressure protein concentrations that's all very very interesting okay now a very important topic regulations in a 70 kilogram man the combined blood flow through both the kidneys is about 1100 milliliters per minute I have it is about 22 of the total cardiac output so that's very important per minute as with other tissues blood flow supplies the kidney with nutrients and removes the waste product IT Supplies the nutrient removes the waste product however the high blood flow to the kidneys greatly exceeds this need actually kidneys purpose of this additional flow is to supply enough plasma for the high rates of glomerular filtration that your body major solutely concentrations as might be expected the mechanisms that regulate renal blood flow are closely linked to control the GFR and exterior functions of the kidney blood supply Joanna it isn't a very fine-tuned controller bees chapters make a blood supply now renal blood flow and oxygen consumption a philosophical type discussion collecting dog because of the reabsorption of sodium there is active transport sodium potassium pumps the point of the whole heading is oxygen consumption is used for transport of sodium okay now on upper gram weight basis the kidney normally consumes oxygen at twice the rate of the brain and have almost seven times the blood flow of the brain it has the blood flow does the oxygen deliver to the kidney for exceeds their metabolic needs a large fraction of the oxygen consumed by the kidney is related to the high rate of active sodium absorption so sodium absorption if renal blood flow and GFR are reduced the less sodium is filtered and if the less sodium is filtered less oxygen is consumed so that sort of thing you know sodium absorbing therefore the renal oxygen consumption varies in proportional to renal tubular sodium reabsorption which in turn is closely related to the GFR Point per gfrah increase in GFR so okay that sort of thing now determinants of renal blood flow very important heading renal blood flow this is what we call renal blood flow is determined by the pressure gradient across the renal vasculature yeah renal artery pressure arteries it makes the resistance divided by the total resistance low yet controls the renal blood flow is equations total resistance increase because that's a mathematical equation if somebody if something goes up here it has to go down here vascular resistance biologically be it should make sense to you now suppose this is a kidney okay um you know there is increase in pressure or vasoconstriction what will happen because renal blood flow so resistance is very very important okay now most of the renal vascular resistance is residing in three major segments and they include interlobular artery uh friend arterial and efferent arterioles capillaries not actually the capillaries even more than the capillary is the interlobular artery a major contributors towards the resistance resistance blood comes from the artery into these set of smaller arteries than afferent arterial glomerular capillary efferent arterial peritubular small veins and vein you see it includes the interlobular artery afferent arterial glomerul Capri maybe coffee come resistance or efferent artery because other resistance so you should know okay what is the major contributor of resistance to the renal blood flow okay resistance resistance they're related inversely to each other okay an increase in the resistance of any vascular segment of the kidney tend to reduce the blood flow again same equation resistance okay although changes in the arterial pressure have some influence on the renal blood flow usually blood pressure changes say an arterial pressure usually our blood pressure is 120 80 systolic diastolic mechanism for most of the time not always okay but for most of the time it maintains its blood pressure or blood supply via autoregulation so nothing to worry about now blood flowing the vaser vector is outer layer they were all the uh glomerular Bowman capsule while a part of the Nephron bombing capsule or glomerular units under Loop of Henley and all these things so blood supply measures you have low supply to the cortex cortex bombing capsules so the outer part of the kidney which is the renal cortex receives most of the blood supply and the medulla only gets one to two percentage vessels that is another important one where we talk about physiological control of glomerular filtration rate and renal blood flow filtration if there is increase in blood flow then what will happen GFR will increase that's the simple story okay or blood flow formulas resistance think about it and then try to understand these headings okay they're pretty simple the determination of the GFR is most variable and subject to the physiological control is the hydrostatic pressure hydrostatic pressure glomerular Capital image okay now this variable in turn is influenced by sympathetic nervous system now let's have a look of the strong sympathetic stimulation very strong sympathetic stimulation and two blood vessels blood vessels all these undergo strong vascular construction of the vasculature means increased resistance or increased resistance decrease blood flow or blood flow degrees GFR will go down all of this paragraph explains the same concept now there are some hormones and Arctic White controls of renal function for example norepinephrine epinephrine endothelene all they constrict the renal blood vessels and when they constrict the renal blood vessel what will happen to the blood flow the blood flow will decrease the renal blood flow RBF this will decrease what will happen to GFR the GFR will also decrease okay so norepinephrine epinephrine all these endothelene they all have the capacity for decreased GFR because they constrict the blood vessels okay now Angiotensin 2 is interesting it also constricts the vasculature but it constricts uh preferentially the efferent arterial efferent arterial hair again if you go back to the concept of e Fred arterial this diagram for example artery adjectives foreign arteriole in most physiological condition increase angiotensin level raises the glomerular hydrostatic pressure and therefore it will ultimately increase the GFR okay while reducing the renal blood flow why reducing the renal blood flowy blood vessels blood flow whenever it is decreased so GFR is also decreased by League okay so that's a very interesting scenario to remember because the resistance okay it should be kept in mind that increase Angiotensin 2 formation usually occurs in the circumstances associated with decreased arterial pressure or volume depletion so for example accident okay conditions so that is why it is important in preventing the decrease in GFR it maintains the GFR Angiotensin to what an important molecule at the same time though the reduction in the blood flow blood supply causes by efferent arterial construction contribute to the decrease flow through the peritubular capillaries and all in all it's a very good effects there is increased GFR uh renal blood flow so that's pretty simple stuff prostaglandin and bradycinene they also do the same thing they decrease the vascular resistance and therefore increase the GFR same story nitric oxide Valley nitric oxide or bradycanine prostaglandin in sub say blood vessels renal blood flow burli GFR Burly all that simple thing okay right now we have to talk about Auto regulation of glomerular filtration rate and renal blood flow so kidney has an intrinsic property of not being affected by the blood pressure blood pressure blood supply blood pressure blood supply kidney blood pressure blood supply constant Auto regulations Loops involved blood supply blood supply foreign blood flow and GF are relatively constant despite changes in the arterial blood pressure is in the center this is the bombing capsule yes one of them this is the alphared arterial this is the efferent arterial or a distal convolutely tubular this is the distal tubule okay foreign because they can sense the concentration of sodium within the urine so urine and the distal Community tubules is called macular denser cells now these macular denser cells have the capacity to sense the sodium ion within the urine that's very important point is there are some specialized cells these ones audio specialized cells drugstore glomerular the primary function of the blood flow Auto regulation in most issues is other yeah basically sorry tissues to get rid of the waste products okay now GFR normally remains relatively constant under you know even the blood pressure is changing um I mean High changes such as 75 blood pressure yeah 160 so they're only ten percent change noticed in the GFR and that is very important blood pressure change okay now although the renal why this is important numbers 180 liters per day for example or the tubular reabsorption 178.5 reabs that is the amount that we get rid of usually daily okay only 1.5 liters blood pressure foreign if there is 25 in the GFR just because the blood pressure raises from 100 to 125. uh if this was the change usually if this was the change then kidney would have started releasing 46.5 liters of urine this is your body would have been depleted in terms of the volume so blood body volume depletion systems autoregulation prevents large changes in the GFR and this is largely because of a phenomena called the tubulo glomerular feedback to below glomerular glomerular tubular feedback okay the kidneys have a special feedback mechanism that links the changes in sodium chloride concentration at the macular denser macular density these are specialized cells in the distal tubule okay with the control of the renal arterial resistance and this is called the autoregulation this feedback helps ensure a relatively constant delivery of sodium chloride to the distal tubule and helps prevent any fluctuations in many circumstances this feedback Auto regulates the renewal blood flow and GFR in parallel and how does it work the tubular feedback mechanism has two components number one afferent arteriolar feedback mechanism and efferent arterial feedback mechanism these feedback mechanisms are depending on specialized cells which are called just a glomerular cells the juxtaglomerular complex consists of macular densa which is the initial portion of the distal tubule and JG cells the gesture glomerular cells in the wall of the afferent and the efferent arterioles the macular denser is a specialized macular densa is the specialized group of cells which is specifically designed to sense the sodium concentrations in the urine okay now decreased macular densa sodium causes dilation of afferent arterial and increases the renin release but anyways this is cell senses changes in sodium chloride delivery to the distal tubule experimental Studies have suggested that decrease GFR kcb majesticide GFR degrees say for example there is depletion of body volume diarrhea vomiting hair bleeding excessive body foreign so decrease in the sodium chloride concentration has two effects number one it decreases the resistance to the blood flow through the offend artery all and number two it increases the renin release from the JG cells of the afferent as well as the efferent arterial release from these cells then function uh via the enzymatic system formation of angiotensin one and ultimately Angiotensin 2.10 it effects on ephrine arterial contractors for any reason if there is a decrease GFR such as by reduction in arterial pressure such as by excessive vomiting such as by diarrhea volume depletion whatever there will be reduced hydrostatic pressure and decrease GFR now decrease GFR give us a urine nephrons there will be low sodium in the macular densa a macular density number one arterial afferent size in two all these efforts will increase the GFR to you know restore it that's the whole story okay or is mechanisms because this is the tubule this is the glomerulus tubular glomerular reflexes GFR maintained okay these two components of the tribulo glomerular feedback mechanism operating together by the way of a special anatomical structure they are all there autoregulation is possible okay and uh so actually very nice here nephrons these are the sodium sensors which actually feel okay Angiotensin 2 release Angiotensin II job Angiotensin therefore one of the side effects of using Angiotensin II is reduction in the GFR sometimes so much so okay there is acute kidney shutdown so blockage of angiotens into formation further reduces the GFR so if you are using angiotensin two blockers Geo blood pressure conditions and it can actually lead to sometimes kidney failure okay so blood pressure or kidney failure because side effects in two blockers say GFR come one of the side effect of HE2 is reduce GFR but physiology physiology then you are fine another regular that's the prime regulatory system a primary automatic control hair GFR car okay which is called the myogenic regulations but the point is it is like elastic system other blood pressure If there is a high blood pressure Tojo arterials as simple as that okay which is kind of important message high protein intake and high glucose intake they actually increase the renal blood flow and GFR a concept important if you eat a lot of proteins so protein injections so macular denser will do a couple of things foreign um offering arterial resistance into it will try to restore the GFR so bad protein diet and same is the story for glucose high protein and high glucose diet say gfrigerator and now you know the physiology behind this in Taman blue boxes so that's the end of this chapter there are some other factors explained here but EA ugly chapters I think that was an amazing important and a detailed video please watch the video share with 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