Renal Physiology/pathophysiology

1. How does a NORMAL kidney contribute to hypertension which is primarily caused by renal artery stenosis on the contralateral side? Renin levels in the vein of the affected kidney vs renin levels in the vein of the unaffected kidney?

Increased renin levels in the vein of the unaffected kidney

Decreased renin levels in the vein of the unaffected kidney

Decreased aldosterone levels in the vein of the affected kidney

*Stenosis will result in hypoperfusion of kidney on the same side>Activarion of RAAS, so Renin will be increased in the vein of affected kidney, while it will be Decreased in the vein of unaffected kidney(Because the opposite kidney is perfused just fine and also JGA on that kidney will sense all that extra salt/water that was absorbed because the affected kidney "thought" body was hypovolemic, so basically in unaffected kidney Renin secretion will be decreased)...HOWEVER they asked you contribution of UNAFFECTED kidney to hypertension and best choice would be Aldosterone-induced sodium and water retention, because Aldosterone secretion from Zona glomerulosa which was induced by Ag2 will Make BOTH kidneys retain Na and water and excrete potassium....

Stenosis will result in hypoperfusion of the affected kidney, leading to increased renin levels. However, the unaffected kidney will not experience reduced blood flow and will maintain normal renin levels. Aldosterone, induced by Angiotensin II, acts on both kidneys to retain sodium and water, contributing to hypertension.

Explanation

Stenosis will result in hypoperfusion of the affected kidney, leading to increased renin levels. However, the unaffected kidney will not experience reduced blood flow and will maintain normal renin levels. Aldosterone, induced by Angiotensin II, acts on both kidneys to retain sodium and water, contributing to hypertension.

2. After completing a 12 Km race, a young patient develops dark urine and urine dipstick is positive for glucose. What is the most likely diagnosis?

Exercise-induced acute kidney injury

Type 1 diabetes with ketoacidosis

*RHABDOMYOLYSIS>Release of Myoglobin>KIdney damage.

Dehydration due to excessive sweating

Rhabdomyolysis is the breakdown of muscle tissue that leads to the release of myoglobin, causing kidney damage. This can occur after strenuous physical activity such as a long race. Dehydration due to sweating excessively may not lead to glucose in urine. Type 1 diabetes with ketoacidosis presents with high blood sugar levels, ketones in urine, but not specifically with glucose in urine. Exercise-induced acute kidney injury is a possibility but does not explain the presence of glucose in urine.

Explanation

Rhabdomyolysis is the breakdown of muscle tissue that leads to the release of myoglobin, causing kidney damage. This can occur after strenuous physical activity such as a long race. Dehydration due to sweating excessively may not lead to glucose in urine. Type 1 diabetes with ketoacidosis presents with high blood sugar levels, ketones in urine, but not specifically with glucose in urine. Exercise-induced acute kidney injury is a possibility but does not explain the presence of glucose in urine.

3. 100 kg male...calculate total body water, NWM/Hematocrit...ECF volume, ICF volume, Plasma volume, Interstitial fluid volume,Hematocrit....

Total body water is 40 L and NWM is 60%

Plasma volume is 15 L and Interstitial fluid volume is 5 L

ICF volume is 20 L and ECF volume is 40%

*60% of total mass is TBW and so 60 L here(NWM is whatever is left=40%)...Note that ICF is 40% of TOTAL BODY MASS(NOT TBW)and ECF is 20% of TOTAL Body mass...So here ICF would be 40L, ECF would be 20, you can think about them also in terms of TBW and basically ECF makes up 1/3 of it(1/3 of 60 here would be again 20L, which is 20 % of 100) and ICF makes up 2/3 of TBW(so here 2/3 of 60=40, which is 40% of 100)In summary don't mix up 20 and 40% which refer to TOTAL BODY MASS(here 100kg) vs 1/3 and 2/3 which refer to TBW(60% of Total body mass)*Now if you know ECF then you can find out Volume of plasma and interstitial fluid which together make up this compartment...Now key here too is knowing %, basically Plasma is Only 25%(1/4) of ECF thus here it is 1/4 x 20=5 , while Interstitial fluid is whatever is left from ECF, in our case 15(which obv. is 3/4 or 75% of ECF...)Hematocrit would be around 45 because he is male(Hematocrit is around 45 % of TBW in males and it is around 40% of TBW in females.<because females have more fat and thus less fluid if you know what i mean :)

The correct calculations for total body water, intracellular fluid volume, extracellular fluid volume, plasma volume, interstitial fluid volume, and hematocrit were provided in the answer. The incorrect answers do not align with the correct calculations provided.

Explanation

The correct calculations for total body water, intracellular fluid volume, extracellular fluid volume, plasma volume, interstitial fluid volume, and hematocrit were provided in the answer. The incorrect answers do not align with the correct calculations provided.

4. Calculate patient's Plasma volume, if he is 70 kg male and after injection of 1g of radiolabeled albumin, plasma concentration of radiolabeled albumin is 25 mg/dL (After equilibration)

Plasma volume = 2 Liters

*FIRST of all get your units.....1g=1000 mg... <So your plasma concentraiton of albumin is 25 mg after injection of 1000 mg...So plasma volume=1000/25=40dL(mg's canceled out), they will likely give you answers in Liters so 40 dL=4 LITERS.you could get approximate answer just by knowing body weight(ECF is 20 % of 70, then all you do is calculate 25% of that value, so you get around 3,5 L that way)

Plasma volume = 3 Liters

Plasma volume = 5 Liters

To calculate the plasma volume, we need to divide the amount of radiolabeled albumin injected (1000 mg) by the concentration of albumin in plasma (25 mg/dL). This gives us 40 dL, which is equal to 4 Liters.

Explanation

To calculate the plasma volume, we need to divide the amount of radiolabeled albumin injected (1000 mg) by the concentration of albumin in plasma (25 mg/dL). This gives us 40 dL, which is equal to 4 Liters.

5. Are Amino acids, Glucose, Electrolytes FREELY filtered in the glomerulus? WHY?

*YES they are freely filtered, but Most of the listed substances are REABSORBED, because we need them while garbage(Like creatinine) that was also filtered with them isn't reabsorbed....*The reason those good guys are filtered is that they are around the size of the "Garbage" that should be filtered, so it's kinda necessary evil, in other words these substances along the "Garbage" have to be smaller then 50-60nm, because anything more than that would be blocked from being filtered by SLIT DIAPRHRAGMS of PDOCYTES(Size barrier), while anything that is even larger like BLOOD CELLS/ particles >100 nm moleculres, would be blocked even before that by FENESTRATED capillay epithelium itself...(fenestrations aren't just large enough to let them pass)

Some are freely filtered while others are not due to their sizes

NO, they are not freely filtered in the glomerulus

Only Glucose is freely filtered in the glomerulus

Amino acids, Glucose, and Electrolytes are indeed freely filtered in the glomerulus, along with other substances. Their reabsorption is essential for the body's functioning, while waste products like creatinine are not reabsorbed.

Explanation

Amino acids, Glucose, and Electrolytes are indeed freely filtered in the glomerulus, along with other substances. Their reabsorption is essential for the body's functioning, while waste products like creatinine are not reabsorbed.

6. Which components of Glomerulus are involved in prevention of Filtration of Albumin?

1 layer-FENESTRATED capillary Endothelium which allows free passage of all molecules including Even NEUTRAL charged ones like Albumin

*3 layers-BASEMENT membrane(with Type 4 collagen and HEPARAN SULFATE), Podocyte foot processes of epithelial layer and Even FENESTRATED capillary Endothelium, all make up CHARGE barrier, because they contain NEGATIVELY charged GLYCOPROTEINS which prevent entry of NEGATIVELY charged molecules like Albumin...(Remember - and - repel vs - and + attract each other), so with Nephrotic syndrome when we loose Charge barrier we get Albuminuria/Hypoproteinemia>Decreased oncotic pressure>Edema...

Podocyte foot processes alone create a barrier by physical filtration, irrespective of charge of molecules like Albumin

BASEMENT membrane acts as a sieve only for larger molecules like RBCs, while Albumin being smaller can freely pass through

In the correct answer, it is explained that all 3 layers of the Glomerulus play a role in preventing the filtration of Albumin by creating a charge barrier due to the presence of negatively charged glycoproteins. This charge barrier repels negatively charged molecules like Albumin. The incorrect answers provide alternative scenarios that do not accurately describe the components involved in preventing the filtration of Albumin.

Explanation

In the correct answer, it is explained that all 3 layers of the Glomerulus play a role in preventing the filtration of Albumin by creating a charge barrier due to the presence of negatively charged glycoproteins. This charge barrier repels negatively charged molecules like Albumin. The incorrect answers provide alternative scenarios that do not accurately describe the components involved in preventing the filtration of Albumin.

7. What can you say about the volume of plasma from which the substance(X) is completely cleared per unit time (Cx measured in mL/min) if the urine flow rate is higher? If the urine concentration of X is higher? If plasma concentration of X is higher?

If the plasma concentration of X is higher, the urine concentration of X would be higher as well.

*Well it makes sense that increased urine flow would be manifestation of increased clearance, it also makes sense that if you have higher clearance you would excrete substance more into urine, so urine concentration would increase while Plasma concentration would decrease...hence the formula we haveCx=U(urine concentration)timesV(Urine flow rate)/P(plasma concentration)

The volume of plasma from which the substance(X) is cleared would decrease if the urine flow rate is higher.

If the urine concentration of X is higher, the plasma concentration of X would also be higher.

When the urine flow rate is higher, the clearance of the substance increases, leading to more substance being excreted in urine. This results in higher urine concentration and lower plasma concentration. Higher urine concentration with higher urine flow rate means more substance is being removed from plasma. As a result, the volume of plasma from which the substance is cleared per unit time increases.

Explanation

When the urine flow rate is higher, the clearance of the substance increases, leading to more substance being excreted in urine. This results in higher urine concentration and lower plasma concentration. Higher urine concentration with higher urine flow rate means more substance is being removed from plasma. As a result, the volume of plasma from which the substance is cleared per unit time increases.

8. How can GFR be indirectly determined and how can this help differentiate the properties of different substances in terms of net secretion/reabsorption?

Inulin is always secreted and never reabsorbed in the kidney.

GFR is solely determined by the amount of urine produced per day.

GFR is directly measured through a blood test.

*GFR is approximately equal To Inulin clearance(and that's how they give you info about GFR), because while FREELY Filtered, inulin is NOT reabsorbed or secreted....so When GFR=Clearance=There is no reabsorbtion or secretion(Like inulin), thus obviously when Clearance of substance<Clearance of Inulin(represents GFR) we could say that substance is "NET reabsorbed" while if clearance of substance>clearance of inulin then we could say that it is "NET secreted"...Normal GFR is around 100 and they can make you approximate GFR just by giving you Creatinine values, HOWEVER they could compare creatinine and inulin clearance to check if you know why Creatinine slightly overestimates GFR, and you should know that small amount of creatinine is secreted by renal tubules thus clearance of Creatinine is slightly more than clearance of Inulin and thus it slightly overestimates the GFR.

The correct answer explains how GFR is indirectly determined using inulin clearance and how this information can be used to differentiate net secretion/reabsorption of substances in the kidney.

Explanation

The correct answer explains how GFR is indirectly determined using inulin clearance and how this information can be used to differentiate net secretion/reabsorption of substances in the kidney.

9. How does increased oncotic pressure in Bowman's space and increase in hydrostatic pressure of glomerular capillaries affect GFR?

Both pressures have no effect on GFR as they balance each other out.

Increased oncotic pressure decreases GFR while increased hydrostatic pressure increases GFR.

*BOTH increase GFR because they basically pull the fluid towards Bowman capsulealso remember

These pressures decrease GFR by inhibiting the movement of fluid towards Bowman's capsule.

Increased oncotic pressure in Bowman's space and an increase in hydrostatic pressure of glomerular capillaries together increase the net filtration pressure, causing an increase in the glomerular filtration rate (GFR). This is due to the forces favoring filtration being greater than the opposing forces, leading to more fluid being filtered into Bowman's space.

Explanation

Increased oncotic pressure in Bowman's space and an increase in hydrostatic pressure of glomerular capillaries together increase the net filtration pressure, causing an increase in the glomerular filtration rate (GFR). This is due to the forces favoring filtration being greater than the opposing forces, leading to more fluid being filtered into Bowman's space.

10. Calculate GFR in mL/min if you know this info about inulin: Urine Flow rate = 50mL/hour, Urine concentration = 100mg/dL, Plasma concentration = 60mg/dL.

4.8 mL/min

GFR=50x100/60=83.3ml/HrBUT they asked mL/Min, so you got to divide this by 60.(60 mins=1hr)so answer: 1,4 mL/min....

3.2 mL/min

2.6 mL/min

To calculate GFR, you first multiply the Urine Flow rate (50mL/hour) by the Urine concentration (100mg/dL) and then divide by the Plasma concentration (60mg/dL). This gives 83.3 mL/hr. Since the question requires the answer in mL/min, you need to convert this by dividing by 60 (as 60 mins = 1hr), resulting in 1.4 mL/min.

Explanation

To calculate GFR, you first multiply the Urine Flow rate (50mL/hour) by the Urine concentration (100mg/dL) and then divide by the Plasma concentration (60mg/dL). This gives 83.3 mL/hr. Since the question requires the answer in mL/min, you need to convert this by dividing by 60 (as 60 mins = 1hr), resulting in 1.4 mL/min.

11. Why do we use clearance of PAH to calculate effective renal plasma flow(eRPF)?

*The one that is slightly MORE, because remember that PAH clearance is ALMOST 100% not quiet 100%, so it slightly UNDERestimates EFFECTIVE renal plasma flow..Note that Secretion of PAH happens in Proximal tubule and needs ENERGY dependent Organic Acid transporter....

It doesn't matter whether it is slightly more or slightly less, as PAH clearance accurately reflects effective renal plasma flow.

The one that is slightly LESS, because PAH clearance is almost 100%, so it slightly overestimates effective renal plasma flow.

Effective renal plasma flow cannot be accurately calculated using PAH clearance, as it is not a direct measure of kidney function.

12. Calculate Hematocrit if you know RPF and RBF?

Well RBF=RPF/Plasma...Plasma=RBF/RPF....Plasma also =1-HctSo Hct=1-Plasma.....

Hct = RBF / RPF

Hct = RPF - RBF

Hct = RBF + RPF

To calculate Hematocrit (Hct) when given Renal Plasma Flow (RPF) and Renal Blood Flow (RBF), you use the formula Hct = 1 - (RBF / RPF). This formula takes into account the relationship between RBF and RPF to determine the Hematocrit level.

Explanation

To calculate Hematocrit (Hct) when given Renal Plasma Flow (RPF) and Renal Blood Flow (RBF), you use the formula Hct = 1 - (RBF / RPF). This formula takes into account the relationship between RBF and RPF to determine the Hematocrit level.

13. Is infusion of Prostaglandins expected to increase Filtration fraction? Note, normal value is around 20%.... contrast this with Ag2 effects.

*NO, because dilation of Afferent(Arriving)arterioles will increase RPF and GFR in the same proportion so their ratio(GFR/RPF) will stay the same...*NSAIDs block the normal vasodilatory effect of prostaglandins on afferent arterioles and thus can lead to Kidney Ischemia...vsAg2 preferentially CONSTRICTS Efferent(Exiting) arterioles, and so blood can't get out from glomeruli as much and so more is filtered out, so GFR Increases, because there is constriction at the outflow, not as much Plasma can get inside so RPF decreases, so overall GFR/RPF ratio(Fitration fraction) will Increase...<ACE inhibitors block Ag2 formation and thus prevent Efferent arteriolal constriction and thus they prevent hyperfiltration damage by deceasing GFR,Increasing RPF and Decreasing FF...

*YES, since Prostaglandins have a direct effect on increasing Filtration fraction by altering the flow of blood in the kidneys...

*NO, because the infusion of Prostaglandins directly leads to a decrease in Filtration fraction due to their impact on the renal blood flow...

*YES, because dilation of Afferent(Arriving) arterioles will increase RPF and GFR in the same proportion resulting in an increase in Filtration fraction...

14. Calculate Filtered Load if you know GFR(110 mL/min) and Plasma concentration of Drug (10 mg/mL).

A) Filtered Load = GFR + Plasma concentration (110 + 10 = 120 mg/min).

*Filtered Load=GFR x Plasma concentraiton(in our case 110x10=1100mg/min)...OHHH you ready???sorry man but you got to know your units, don't risk your score because of this sht....*Filtered Load-mg/minute*Plasma concentration-mg/mL*GFR-ml/minJUST In case lol: 1L=1000mL, 1g=1000mg

B) Filtered Load = GFR - Plasma concentration (110 - 10 = 100 mg/min).

C) Filtered Load = GFR / Plasma concentration (110 / 10 = 11 mg/min).

Filtered Load is calculated by multiplying the Glomerular Filtration Rate (GFR) by the Plasma concentration of the drug. Remember to pay attention to the units - GFR is in mL/min, and Plasma concentration is in mg/mL, so the resulting Filtered Load will be in mg/min.

Explanation

Filtered Load is calculated by multiplying the Glomerular Filtration Rate (GFR) by the Plasma concentration of the drug. Remember to pay attention to the units - GFR is in mL/min, and Plasma concentration is in mg/mL, so the resulting Filtered Load will be in mg/min.

15. Why INCREASED plasma protein concentration and Constriction of ureters can result in INCREASED FF?effects on RPF and GFR?

*DO NOT TRY TO memorize this stuff you will mess it up, JUST logically deduce from basic physiology, If you have High plasma protein concentration that means that you have high oncotic pressure in the capillaries which will hold on to the fluid and say " IT IS MINE BITCH" and won't let it go easily(i.e Won't let it be filtered so easily) so Fitration Fraction will be decreased, NOW with Constriction of ureters, you basically can't get the fluid from your kidneys into your bladder, so basically fluid backs up into the ureters and eventually ends up in INCREASING hydrostatic pressure in BOWMAN capsule(remember that you want to get flud IN the bowman capsule with filtration but now you increase pressure that works against it), so yea here again you will get decreased GFR and FF...BUT Very important to note(They will try to confuse you on this): RENAL PLASMA FLOW Is NOT affected with Changes in plasma proteins/ureter constriction...

B. Increased plasma protein concentration has no effect on FF, while constriction of ureters leads to increased RPF and GFR.

A. Increased plasma protein concentration leads to decreased FF, while constriction of ureters leads to increased RPF and GFR.

C. Increased plasma protein concentration leads to increased FF, while constriction of ureters has no effect on RPF and GFR.

The correct answer explains how increased plasma protein concentration and constriction of ureters actually lead to decreased FF, RPF, and GFR. The incorrect answers provide alternative scenarios that do not align with the physiological effects described in the correct answer.

Explanation

The correct answer explains how increased plasma protein concentration and constriction of ureters actually lead to decreased FF, RPF, and GFR. The incorrect answers provide alternative scenarios that do not align with the physiological effects described in the correct answer.

16. Why does FF decrease with dehydration despite GFR and RPF both going down?

*Well Simply because the RPF goes down MORE than GFR does, so FF= GFR/RPF ratio will go UP.....

Because GFR goes down more than RPF does.

Due to an increase in capillary hydrostatic pressure and a decrease in capillary oncotic pressure.

As a result of an increase in circulating volume in ECF.

When considering the filtration fraction (FF), it is essential to look at how the ratio of GFR to RPF changes. In the case of dehydration, although both GFR and RPF decrease, the reduction in RPF outweighs the decrease in GFR, leading to a decrease in FF. This is due to the fact that the RPF goes down more significantly than GFR, causing the FF to decrease despite the individual reductions in GFR and RPF.

Explanation

When considering the filtration fraction (FF), it is essential to look at how the ratio of GFR to RPF changes. In the case of dehydration, although both GFR and RPF decrease, the reduction in RPF outweighs the decrease in GFR, leading to a decrease in FF. This is due to the fact that the RPF goes down more significantly than GFR, causing the FF to decrease despite the individual reductions in GFR and RPF.

17. Which variables do and don't you need to calculate Excretion rate?

You need Inulin clearance and Plasma concentration, but not Tubular reabsorption of Substance X, to calculate Excretion rate.

You need PAH clearance, Plasma concentration, and Tubular reabsorption of Substance X to calculate Excretion rate.

*Well you don't need PAH clearance, all you need is Inulin clearance(GFR), Plasma conentration and tubular reabsorbtion of substance X.So Excretion rate=(Inulin clearancexPlasma concentration)-Tubular reabsorbtion of substance X....

You need PAH clearance, Inulin clearance, and Tubular reabsorption of Substance X to calculate Excretion rate.

18. If GFR, Px, V, and Ux are given, how can the reabsorption rate and excretion rate for substance X be calculated?

Reabsorption rate = (GFR x Px) + (V x Ux) ; Excretion rate = (V x Ux) - (GFR x Px)

Reabsorption rate = (GFR x Ux) - (V x Px) ; Excretion rate = (V x Px) - (GFR x Ux)

*Reabsorbtion rate=Filtered-Exreted(due to reabsorbtion excretion rate is less than filtering rate)Thus reabsorbtion rate=(GFR times Px) -(V times Ux)vs Secretion rate=Excreted rate-Filtered rate=(V times Ux)-(GFR times Px)

Reabsorption rate = (GFR x Px) - (V x Ux) ; Excretion rate = (V x Ux) + (GFR x Px)

The correct calculation for reabsorption rate involves subtracting the product of GFR and Px from the product of V and Ux. Likewise, the correct calculation for excretion rate involves subtracting the product of GFR and Px from the product of V and Ux.

Explanation

The correct calculation for reabsorption rate involves subtracting the product of GFR and Px from the product of V and Ux. Likewise, the correct calculation for excretion rate involves subtracting the product of GFR and Px from the product of V and Ux.

19. What is Fractional Excretion of Sodium=FE(Na) and what is its significance? How can we calculate it?

FE(Na) measures the amount of sodium absorbed by the intestines.

FE(Na) is only used for diagnosing diabetes insipidus.

*FE(Na) is basically Proportion(%) of the sodium filtered by kidney which is EXCRETED in urine...We often use it to differentiate between Hypovolemia and decreased Effective circulating Plasma volume as potential cause for Acute renal failure...understanding formula is tough unless you know the definition, let me break it down for you, you basically want to find how much Na peed out and then compare this to total amount that passed(was filtered) trough kidney...Easiest way to keep this formula straight is FE(Na)=EXCRETION RATE/FILTRATION RATE, now you just have to remember that Excretion/Filtration rates and you will get something like this FE(Na)=VxUna/GFRxPna....but instead of GFR they will make you calculate CLEARANCE OF CREATININE(which =Ucr x V/Pcr)...Once again don't memorize these try to deduce from the One concept:Excretion rate/Filtration rate.NOW they might present answer in ratio form so you got to know this derivative formula FE(Na)=Pcr x Una/Ucr x Pna(basically Plasma creatinine times Urine Sodium/Urine creatinine xPlasma Sodium)

FE(Na) is calculated by dividing urine sodium by urine potassium levels.

FE(Na) is a measure of the proportion of sodium filtered by the kidney that is excreted in urine. It is primarily used to distinguish between different causes of acute renal failure. The correct formula to calculate FE(Na) is Excretion Rate / Filtration Rate.

Explanation

FE(Na) is a measure of the proportion of sodium filtered by the kidney that is excreted in urine. It is primarily used to distinguish between different causes of acute renal failure. The correct formula to calculate FE(Na) is Excretion Rate / Filtration Rate.

20. What is 'Splay' and what mechanism underlies this phenomenon?

C) Splay refers to the situation where the kidneys reabsorb all substances without any excretion, leading to accumulation of waste in the body.

A) Splay represents the point at which all renal reabsorption carriers are saturated, occurring at a Tm of 375.

B) Splay is the term used to describe the complete absence of a substance in urine regardless of the amount consumed or produced.

*Splay is the difference between urine threshold(the amount of a substance required in the kidneys before it appears in urine and this amount equals 200mg/dL) and saturation, or TM in this instance, saturation refers to an exhausted supply of renal reabsorption carriers, Tm is 375 and that's when ALL transporters are saturated, however whole mechanism of Splay is HETEROGENICITY of nephrons in that some of them begin to excrete Glucose earlier then others, due to their Different(lower) TmG values(Tubular maximum for glucose don't confuse with Tm when all the transporters everywhere are already saturated).../

The correct answer explains that Splay is the result of the heterogenicity of nephrons, causing some to excrete glucose earlier due to different TmG values. The incorrect answers provide alternative statements that do not accurately describe the concept of Splay.

Explanation

The correct answer explains that Splay is the result of the heterogenicity of nephrons, causing some to excrete glucose earlier due to different TmG values. The incorrect answers provide alternative statements that do not accurately describe the concept of Splay.

21. How do ACE inhibitors decrease blood pressure?

By stimulating aldosterone synthesis

By promoting Na reabsorption in the proximal tubule

By increasing the production of Angiotensin II

*Basically by blocking affects of Angitoensin II..1)So prevents Ag2 mediated stimulation of Na reabsorbtion in proximal tubule(Ag2 would normally sitmulate Na/H exchanger which would promote Na reabsorbtion in exchange for H secretion)2)Also prevents Na reabsorbtion by Na/Cl cotransporter, as this transporter is also stimulated by Ag2.3)block of Ag2 synthesis will remove DIRECT sitmulator of Aldosteorne synthesis>Less aldosterone>Less water/Na retention...4)Ag2 would normally cause Vasoconstriction of vessels,so this effect is prevented too.

ACE inhibitors work by inhibiting the enzyme that converts Angiotensin I to Angiotensin II, thereby reducing the levels of Angiotensin II in the body. This leads to decreased vasoconstriction, sodium reabsorption in the kidneys, and aldosterone synthesis, ultimately resulting in a lowering of blood pressure.

Explanation

ACE inhibitors work by inhibiting the enzyme that converts Angiotensin I to Angiotensin II, thereby reducing the levels of Angiotensin II in the body. This leads to decreased vasoconstriction, sodium reabsorption in the kidneys, and aldosterone synthesis, ultimately resulting in a lowering of blood pressure.

22. In which part of Nephron is Ammonia(NH3) created and secreted? What is its significance?

*NH3 acts as a BUFFER for Secreted H+ ions(H+secretion is stimulated by Ag2 which stimulates Na/H exchangee)*NH3 is CREATED and Secreted in EARLY PROXIMAL convoluted tubule.

NH3 is created and secreted in the distal convoluted tubule.

NH3 is created and secreted in the loop of Henle.

NH3 is created and secreted in the collecting duct.

23. Site of Digoxin secretion?

*PROXIMAL convoluted tubules, so Renal insufficiency>Increased toxicity of Digoxin(Like prolonged PR interval,Hyperkalemia,Diarrhea,Vision changes)

Loop of Henle

Collecting ducts

Distal convoluted tubules

Digoxin is primarily secreted in the PROXIMAL convoluted tubules of the kidneys. Renal insufficiency can lead to increased toxicity of Digoxin, manifesting as prolonged PR interval, hyperkalemia, diarrhea, and vision changes.

Explanation

Digoxin is primarily secreted in the PROXIMAL convoluted tubules of the kidneys. Renal insufficiency can lead to increased toxicity of Digoxin, manifesting as prolonged PR interval, hyperkalemia, diarrhea, and vision changes.

24. In which part of nephron is reabsorption of HCO3 highest?

*EARLY PROXIMAL convoluted tubule...But in the lumen it is first converted to H2CO3 by combining with H+, then H2CO3 is broken down to CO2, H2O by Carbonic anhydrase, then Then CO2 passively diffuses into the PCT cells, combines with H2O(Which is PASSIVELY reabsorbed in PCT) and CO2+H2O will be combined into H2CO3 by INtracellular Carbonic anhydrase, then H2CO3 is broken into H and HCO3 intracellularly and for every HCO3 that moves into the Interstitium/Blood, one H+ is secreted into the Lumen(for excretion)....Note that thus Carbonic Anhydrase blockers(Which obviously causes loss of HCO3 and thus induce Metabolic acidosis) work on PROXIMAL CT.(Like ACETAZOLAMIDE)

Collecting duct

Distal convoluted tubule

Descending limb of loop of Henle

The reabsorption of HCO3 is highest in the early proximal convoluted tubule due to the intricate process involving carbonic anhydrase and H+ secretion. This process is essential for maintaining acid-base balance in the body.

Explanation

The reabsorption of HCO3 is highest in the early proximal convoluted tubule due to the intricate process involving carbonic anhydrase and H+ secretion. This process is essential for maintaining acid-base balance in the body.

25. Which part of the Nephron permits CONTRACTION alkalosis and why?

*Well PCT because that's where Na/H exchanger is located which pumps out(promotes excretion) of H in exchange for reabsorbtion of Na, so basically this transporter can let H+ waste into the pee just to pump Na into the cells, so you loose your H>Increases Ph and Contraction alkalosis.Note that activity of this Exchanger is increased by Ag2 and thus can be decreased by ACE inhibitors...

Collecting duct because it is responsible for the final concentration of urine by reabsorbing water and regulating electrolytes.

Glomerulus because it filters blood and forms the initial urine that is further processed along the Nephron.

Loop of Henle because it plays a crucial role in maintaining the concentration gradient in the medulla of the kidney.