Renal System Questions

1. What does the mesonephros give rise to?

Functions as the permanent kidney in fetal life.

The mesonephros has no developmental significance.

Gives rise to the Mullerian duct in the male genital system.

Functions as an interim kidney in the 1st trimester of fetal life, gives rise to the Wolffian duct of the male genital system, and the caudal end of the mesonephros gives rise to the uteric bud (which becomes ureter, pelvis, calyces and collecting ducts)

2. What structures does the metanephric duct give rise to?

Small intestine and colon

Liver and gallbladder

Lung alveoli and bronchioles

Glomerulus and renal tubules to the distal convoluted tubule (via interaction with the uteric bud)

The metanephric duct gives rise to the glomerulus and renal tubules, including the distal convoluted tubule, through its interaction with the uteric bud during kidney development. The incorrect answers are not related to the developmental process of the kidney.

Explanation

The metanephric duct gives rise to the glomerulus and renal tubules, including the distal convoluted tubule, through its interaction with the uteric bud during kidney development. The incorrect answers are not related to the developmental process of the kidney.

3. What is the most common site of renal obstruction (hydronephrosis) in the fetus?

The renal pelvis. It is less likely to cause obstruction.

The uteropelvic junction wiht the kidney. It is the last to canalize.

The bladder neck. It is most susceptible to blockages.

The proximal urethra. It is prone to narrowing.

In the fetus, the uteropelvic junction within the kidney is the most common site of renal obstruction due to its late canalization. This can lead to hydronephrosis and other complications. The bladder neck, proximal urethra, and renal pelvis are not common sites of obstruction compared to the uteropelvic junction.

Explanation

In the fetus, the uteropelvic junction within the kidney is the most common site of renal obstruction due to its late canalization. This can lead to hydronephrosis and other complications. The bladder neck, proximal urethra, and renal pelvis are not common sites of obstruction compared to the uteropelvic junction.

4. What is Potter's syndrome and what does it result in?

Potter's syndrome is a rare autoimmune disease that affects the joints and causes inflammation.

Potter's syndrome is a neurological condition that results in seizures and impaired motor function.

Potter's syndrome is a genetic disorder characterized by excessive hair growth and thickened skin.

Bilateral renal agenesis due to malformation of the ureteric bud. Leads to oligohydramnios, which causes limb deformities, facial deformities, and pulmonary hypoplasia (from increased thoracic pressure).

5. A neonate presents with limb deformities, facial deformities, pulmonary hypoplasia, and oligohydramnios. What is the disease? What is it caused by?

Potter's syndrome (bilateral renal agenesis) due to malformation of the ureteric bud.

Treacher Collins syndrome due to mutations in the TCOF1 gene.

Achondroplasia due to a mutation in the FGFR3 gene.

Ehlers-Danlos syndrome due to defects in collagen synthesis.

Potter's syndrome is characterized by the combination of limb deformities, facial deformities, pulmonary hypoplasia, and oligohydramnios, which is caused by bilateral renal agenesis leading to decreased amniotic fluid. The incorrect answers do not match the clinical presentation and etiology described in the question.

Explanation

Potter's syndrome is characterized by the combination of limb deformities, facial deformities, pulmonary hypoplasia, and oligohydramnios, which is caused by bilateral renal agenesis leading to decreased amniotic fluid. The incorrect answers do not match the clinical presentation and etiology described in the question.

6. Where is a horseshoe kidney most likely located in the abdomen?

Beside the spleen.

Under the inferior mesenteric artery.

Behind the liver.

Above the pancreas.

A horseshoe kidney is most likely located under the inferior mesenteric artery due to its unique shape and positioning in the abdomen.

Explanation

A horseshoe kidney is most likely located under the inferior mesenteric artery due to its unique shape and positioning in the abdomen.

7. How do you calculate renal clearance of x?

Cx = Ux/V * Px

Cx = Ux - V + Px

Cx = UxV/Px where C is clearance of x, V is the urine flow rate, and P is the plasma concentration of x

Cx = Ux * V + Px

To calculate renal clearance of X, the correct formula is Cx = UxV/Px, where C is clearance, V is urine flow rate, and P is plasma concentration. The incorrect answers provide variations that do not accurately represent the calculation.

Explanation

To calculate renal clearance of X, the correct formula is Cx = UxV/Px, where C is clearance, V is urine flow rate, and P is plasma concentration. The incorrect answers provide variations that do not accurately represent the calculation.

8. Two equations used to calculate GFR?

GFR = UcreatinineV/Pcreatinine = CcreatinineGFR = Kf [(PGC-PBS) - (?GC-?BS)]

GFR = UinulinV/Pinulin = CinulinGFR = Kf [(PGC-PBI) - (?GC-?BS)]

GFR = UinulinV/Pinulin = CinulinGFR = Kf [(PGC-PBS) - (?GC-?BS)]Note: Creatinine clearance can also be used as an approximate measure of GFR

GFR = UinulinV/Pinulin = CinulinGFR = Kf [(PGC-PBS) - (?GC-?SB)]

The correct equation for GFR involves the terms Uinulin, Pinulin, Cinulin, Kf, PGC, and PBS. Altering any of these terms in the equations will result in an incorrect calculation of GFR.

Explanation

The correct equation for GFR involves the terms Uinulin, Pinulin, Cinulin, Kf, PGC, and PBS. Altering any of these terms in the equations will result in an incorrect calculation of GFR.

9. What is the formula for renal blood flow (RBF)?

RPF/(1+Hct)

RPF*(1-Hct)

RPF+(1/Hct)

RPF/(1-Hct)

The correct formula for renal blood flow (RBF) is RPF/(1-Hct), where RPF is renal plasma flow and Hct is hematocrit. This formula takes into account the fraction of blood that is made up of red blood cells.

Explanation

The correct formula for renal blood flow (RBF) is RPF/(1-Hct), where RPF is renal plasma flow and Hct is hematocrit. This formula takes into account the fraction of blood that is made up of red blood cells.

10. What is meant by filtration fraction?

The percentage of glucose reabsorbed from the glomerular filtrate

The amount of blood filtered by the kidneys in a minute

FF = GFR/RPF (normally ~20%)

The ratio of glomerular capillary pressure to Bowman's capsule pressure

Filtration fraction is a calculation that represents the percentage of the plasma passing through the glomeruli that is actually filtered to form urine. It is calculated by dividing the glomerular filtration rate (GFR) by the renal plasma flow (RPF), and is typically around 20% in a healthy individual.

Explanation

Filtration fraction is a calculation that represents the percentage of the plasma passing through the glomeruli that is actually filtered to form urine. It is calculated by dividing the glomerular filtration rate (GFR) by the renal plasma flow (RPF), and is typically around 20% in a healthy individual.

11. What is the equation for filtered load?

Filtered load = GFR - plasma concentration

Filtered load = GFR / plasma concentration

Filtered load = GFR x plasma concentration

Filtered load = GFR + plasma concentration

12. Where is glucose reabsorbed? Where is PAH secreted?

In the glomerulus and excreted in the renal pelvis.

In the loop of Henle and excreted in the distal tubule.

In the distal tubule and excreted in the collecting duct.

Both occur in the proximal tubule.

Glucose reabsorption and PAH secretion both primarily take place in the proximal tubule of the nephron. The other options provided involve incorrect locations within the renal tubules for these processes to occur.

Explanation

Glucose reabsorption and PAH secretion both primarily take place in the proximal tubule of the nephron. The other options provided involve incorrect locations within the renal tubules for these processes to occur.

13. How do you calculate the fraction of filtered H2O reabsorbed?

Fraction of filtered H2O reabsorbed = 1 - 1/[TF/P]

Fraction of filtered H2O reabsorbed = TF/P

Fraction of filtered H2O reabsorbed = P/TF

Fraction of filtered H2O reabsorbed = TF * P

The correct formula for calculating the fraction of filtered H2O reabsorbed involves taking 1 and subtracting it from 1 divided by the ratio of tubular fluid to plasma concentration (TF/P). This helps determine the amount of water that has been reabsorbed in the process.

Explanation

The correct formula for calculating the fraction of filtered H2O reabsorbed involves taking 1 and subtracting it from 1 divided by the ratio of tubular fluid to plasma concentration (TF/P). This helps determine the amount of water that has been reabsorbed in the process.

14. What does the ratio [TF/Px]/[TF/Pinulin] tell you? What does it correct for?

It indicates the rate of blood flow through the renal arteries.

It measures the concentration of electrolytes in the blood plasma.

It provides information on the total volume of urine produced by the kidneys.

It gives you the fraction of the filtered load of a substance remaining at any point along the nephron by correcting for water absorption. With this correction, you can know whether a substance has been reabsorbed, secreted or neither.

The ratio [TF/Px]/[TF/Pinulin] specifically corrects for water absorption in order to determine the fate of a substance along the nephron, not the total urine volume, concentration of electrolytes, or blood flow rate through renal arteries.

Explanation

The ratio [TF/Px]/[TF/Pinulin] specifically corrects for water absorption in order to determine the fate of a substance along the nephron, not the total urine volume, concentration of electrolytes, or blood flow rate through renal arteries.

15. What is acetazolamide? What are its two clinical uses?

A beta-blocker used for lowering blood pressure.

An antibiotic used for treating skin infections.

An antihistamine used for treating allergies.

A carbonic anhydrase inhibitor (prevents conversion of CO2 to HCO3-). Acts as a proximal tube diuretic, inhibiting reabsorption of filtered HCO3- in the proximal tubule, indirectly preventing reabsorption of Na+. It is also used in acute mountain sickness to relieve the symptoms of respiratory alkalosis.

Acetazolamide is a carbonic anhydrase inhibitor with clinical uses as a diuretic and in treating acute mountain sickness. It is not an antibiotic, antihistamine, or beta-blocker.

Explanation

Acetazolamide is a carbonic anhydrase inhibitor with clinical uses as a diuretic and in treating acute mountain sickness. It is not an antibiotic, antihistamine, or beta-blocker.

16. What is glomerulotubular balance? What is the mechanism?

Glomerulotubular balance is a term used to describe the movement of blood through the glomerulus, and it is not influenced by changes in GFR or ECF volume.

The mechanism of glomerulotubular balance is solely dependent on the concentration of proteins in the blood plasma, not on the GFR or ECF volume status.

The idea that there is a constant fractional reabsorption of NA+ and H2O, so that if GFR increases, so does Na+ reabsorption. Starling forces govern how much isosmotic fluid is reabsorbed: an increase in GFR causes an increase in ?GCand decrease in PGC, thus increasing fluid reabsorption. In the same way, ECF volume contraction increases reabsorption and expansion decreases it.

Glomerulotubular balance refers to the filtration pressure within the glomerulus with no relation to Na+ reabsorption.

Glomerulotubular balance refers to the concept that there is a consistent reabsorption of sodium (Na+) and water in the renal tubules. It is influenced by changes in glomerular filtration rate (GFR) and extracellular fluid (ECF) volume, leading to adjustments in fluid reabsorption.

Explanation

Glomerulotubular balance refers to the concept that there is a consistent reabsorption of sodium (Na+) and water in the renal tubules. It is influenced by changes in glomerular filtration rate (GFR) and extracellular fluid (ECF) volume, leading to adjustments in fluid reabsorption.

17. What percentage of Na+ is reabsorbed in the proximal tubule? By what mechanisms?

50%. Reabsorbed solely by passive diffusion.

40%. Reabsorbed through a process of excretion in the proximal tubule.

67% (2/3). In the early proximal tubule, by cotransport with glucose, amino acids, phosphate and lactate, and countertransport with H+ and subsequently reabsorbed with HCO3-. In the Late proximal tubule, Na+ reabsorbed with Cl-.

85%. Reabsorbed by active transport only in the late proximal tubule.

The correct answer is 67% (2/3) as Na+ is reabsorbed in the proximal tubule through various mechanisms involving cotransport and countertransport with other ions. Options 1, 2, and 3 are incorrect as they misrepresent the actual processes involved in Na+ reabsorption in the proximal tubule.

Explanation

The correct answer is 67% (2/3) as Na+ is reabsorbed in the proximal tubule through various mechanisms involving cotransport and countertransport with other ions. Options 1, 2, and 3 are incorrect as they misrepresent the actual processes involved in Na+ reabsorption in the proximal tubule.

18. Which of the following is a proximal tubule diuretic?

Acetazolamide.

Spironolactone

Hydrochlorothiazide

Furosemide

Acetazolamide is a carbonic anhydrase inhibitor that acts in the proximal tubule of the kidney to inhibit reabsorption of bicarbonate and sodium, leading to diuresis. Furosemide is a loop diuretic, Spironolactone is a potassium-sparing diuretic, and Hydrochlorothiazide is a thiazide diuretic, all of which act in different parts of the nephron.

Explanation

Acetazolamide is a carbonic anhydrase inhibitor that acts in the proximal tubule of the kidney to inhibit reabsorption of bicarbonate and sodium, leading to diuresis. Furosemide is a loop diuretic, Spironolactone is a potassium-sparing diuretic, and Hydrochlorothiazide is a thiazide diuretic, all of which act in different parts of the nephron.

19. Name 3 loop diuretics. What do they inhibit? In which part of the nephron?

Furosemide, ethacrynic acid and bumetanide. They inhibit the Na+-K+-2Cl- contransporter in the thick ascending limb.

Acetazolamide, mannitol, and amiloride. They inhibit the Na+-Cl- cotransporter in the proximal convoluted tubule.

Hydrochlorothiazide, spironolactone, and triamterene. They inhibit the Na+-Cl- cotransporter in the distal convoluted tubule.

Chlorthalidone, indapamide, and metolazone. They inhibit the Na+-K+-2Cl- contransporter in the collecting duct.

Loop diuretics such as furosemide, ethacrynic acid, and bumetanide work by inhibiting the Na+-K+-2Cl- contransporter in the thick ascending limb of the loop of Henle. The incorrect answers provided target different parts of the nephron and use other classes of diuretics with their respective mechanisms of action.

Explanation

Loop diuretics such as furosemide, ethacrynic acid, and bumetanide work by inhibiting the Na+-K+-2Cl- contransporter in the thick ascending limb of the loop of Henle. The incorrect answers provided target different parts of the nephron and use other classes of diuretics with their respective mechanisms of action.

20. What direct action does angiotensin II have on the nephron?

Increases proximal tubule Na+/H+ exchange, resulting in Na+ and H2O reabsorption (this can exacerbate contraction alkalosis)

Inhibits distal tubule Na+/Cl- cotransport, leading to excretion of Na+ and water

Stimulates collecting duct to increase K+ secretion and decrease water reabsorption

Blocks Na+/K+/2Cl- cotransport in loop of Henle, reducing Na+ reabsorption

Angiotensin II primarily acts on the proximal tubule to increase Na+/H+ exchange and enhance reabsorption of Na+ and water. This mechanism contributes to the regulation of blood pressure and blood volume through the renin-angiotensin-aldosterone system. The incorrect answers provided describe actions that are not directly related to the effects of angiotensin II on the nephron.

Explanation

Angiotensin II primarily acts on the proximal tubule to increase Na+/H+ exchange and enhance reabsorption of Na+ and water. This mechanism contributes to the regulation of blood pressure and blood volume through the renin-angiotensin-aldosterone system. The incorrect answers provided describe actions that are not directly related to the effects of angiotensin II on the nephron.

21. What are 2 direct effects of PTH on the nephron?

Stimulates Na+ reabsorption in the early proximal tubule.

Inhibits Na+/phosphate cotransport in the early proximal tubule, resulting in phosphate excretion. It does this by activating adenylate cyclase, generating cAMP (thus also increasing urinary cAMP). In the early distal convoluted tubule, it increases Ca2+/Na+ exchange, resulting in Ca2+ reabsorption. Note: PTH also causes 1,25-dihydroxy vitamin D production by the kidney.

Promotes phosphate reabsorption in the late distal tubule.

Decreases Ca2+ reabsorption in the early distal convoluted tubule.

Parathyroid hormone (PTH) has specific effects on the nephron, including modulation of phosphate and calcium handling. The correct answer outlines how PTH affects phosphate excretion and calcium reabsorption in different parts of the nephron.

Explanation

Parathyroid hormone (PTH) has specific effects on the nephron, including modulation of phosphate and calcium handling. The correct answer outlines how PTH affects phosphate excretion and calcium reabsorption in different parts of the nephron.

22. What is bumetanide?

A loop diuretic. Inhibits the Na+-K+-2Cl- contransporter in the thick ascending limb.

A type of anti-inflammatory medication for arthritis.

An antibiotic used to treat bacterial infections.

A beta-blocker commonly prescribed for hypertension.

Bumetanide is specifically known as a loop diuretic as it works in the thick ascending limb of the loop of Henle to inhibit the Na+-K+-2Cl- cotransporter, leading to increased excretion of water and electrolytes.

Explanation

Bumetanide is specifically known as a loop diuretic as it works in the thick ascending limb of the loop of Henle to inhibit the Na+-K+-2Cl- cotransporter, leading to increased excretion of water and electrolytes.

23. How is Na+ reabsorbed in the early distal convoluted tubule? What diuretic has its action at this site?

Potassium-sparing mechanism. This is the site of action of aldosterone antagonists (e.g., spironolactone).

Aquaporins. This is the site of action of carbonic anhydrase inhibitors (e.g., acetazolamide).

Na+/Cl- cotransporter. THis is the site of action of thiazide diuretics (HCZ)

Sodium channels. This is the site of action of loop diuretics (e.g., furosemide).

In the early distal convoluted tubule, Na+ reabsorption occurs primarily through the Na+/Cl- cotransporter. Thiazide diuretics act at this site by inhibiting this cotransporter, leading to increased Na+ and water excretion. The other incorrect answers describe mechanisms of action of different classes of diuretics at various sites in the nephron.

Explanation

In the early distal convoluted tubule, Na+ reabsorption occurs primarily through the Na+/Cl- cotransporter. Thiazide diuretics act at this site by inhibiting this cotransporter, leading to increased Na+ and water excretion. The other incorrect answers describe mechanisms of action of different classes of diuretics at various sites in the nephron.

24. Where is the cortical diluting segment?

The early distal convoluted tubule is impermeable to water, and thus results in reabsorption of NaCl and dilution of urine. The thick ascending limb is also impermeable to water, and therefore referred to as the diluting segment.

The distal convoluted tubule is the diluting segment.

The collecting duct is the diluting segment.

The proximal convoluted tubule is the diluting segment.

The thick ascending limb is impermeable to water, contributing to the dilution of urine, while the correct answer options (proximal convoluted tubule, collecting duct, distal convoluted tubule) do not play a primary role in urine dilution.

Explanation

The thick ascending limb is impermeable to water, contributing to the dilution of urine, while the correct answer options (proximal convoluted tubule, collecting duct, distal convoluted tubule) do not play a primary role in urine dilution.

25. What are the 2 cell types in the late distal convoluted tubule and collecting duct? What are their functions?

The intercalated cell reabsorbs Na+ via sodium channel and secretes H+ and K+.

The principal cell reabsorbs Na+ via sodium channel and H2O via aquaporins (in absence of ADH there is no insertion of aquaporins, and the principal cells are impermeable to H2O), and secretes K+. The intercalated cell secretes H+ and reabsorbs K+ by K+/H+ ATPase, which responds to aldosterone.

The principal cell reabsorbs H2O via aquaporins and secretes Na+.

The principal cell secretes H+ and reabsorbs K+, the intercalated cell reabsorbs Na+ via sodium channel.

In the late distal convoluted tubule and collecting duct, the principal cell and the intercalated cell have specific functions related to ion reabsorption and secretion, as outlined in the correct answer.

Explanation

In the late distal convoluted tubule and collecting duct, the principal cell and the intercalated cell have specific functions related to ion reabsorption and secretion, as outlined in the correct answer.

26. Name 4 K+ sparing diuretics, What are their mechanisms of action? List 3 clinical uses.

Hydrochlorothiazide, Furosemide, Bumetanide

Spironolactone, Amiloride, Tramterene, eplerenone. Spironolactione is a competitive aldosterone receptor antagoinst in the cortical collecting tubule. Tramterene and amiloride block Na+ channels in the cortical collecting tubule. Hyperaldosteronism, K+ depletion, CHF.

27. What are aldosterone's effects on the nephron?

Decreases Na+ reabsorption by blocking Na+ channels in the nephron.

Promotes excretion of Na+ and K+ through the nephron channels.

Increases Na+ reabsorption by leading to insertion of Na+ channels on the luminal side of the principal cells in the collecting duct. Also indirectly increases secretion of K+ in the principal cells by increasing the Na+ gradient for the Na+/K+ ATPase pump

Has no effect on electrolyte reabsorption in the nephron.

Aldosterone's effects on the nephron involve increasing Na+ reabsorption through the insertion of Na+ channels and indirectly increasing K+ secretion to maintain electrolyte balance.

Explanation

Aldosterone's effects on the nephron involve increasing Na+ reabsorption through the insertion of Na+ channels and indirectly increasing K+ secretion to maintain electrolyte balance.

28. What effect do thiazide and loop diuretics have on K+? Why?

Thiazide and loop diuretics increase K+ secretion, because they increase he flow rate through the distal tubule, causing dilution of the luminal K+ concentration. Thiazide and loop diuretics can therefore cause hypokalemia.

Thiazide and loop diuretics decrease K+ secretion, because they decrease the flow rate through the distal tubule, causing concentration of luminal K+.

Thiazide and loop diuretics increase K+ reabsorption, leading to hyperkalemia.

Thiazide and loop diuretics have no effect on K+ levels.

Thiazide and loop diuretics work by increasing the flow rate through the distal tubule, causing a dilution of luminal K+ concentration and subsequent increase in K+ secretion. This process can result in hypokalemia as a side effect.

Explanation

Thiazide and loop diuretics work by increasing the flow rate through the distal tubule, causing a dilution of luminal K+ concentration and subsequent increase in K+ secretion. This process can result in hypokalemia as a side effect.

29. Where is urea reabsorbed?

The urea is reabsorbed in the outer medullary collecting ducts

50% of urea is reabsorbed in the proximal tubule. Urea is also reabsorbed in the inner medullary collecting ducts, in response to ADH (distal tubule, cortical collecting ducts and outer medullary collecting ducts are impermeable to urea).

The urea is reabsorbed in the distal tubule

The urea is reabsorbed in the cortical collecting ducts

Urea reabsorption primarily occurs in the proximal tubule and inner medullary collecting ducts, not in the distal tubule, cortical collecting ducts, or outer medullary collecting ducts.

Explanation

Urea reabsorption primarily occurs in the proximal tubule and inner medullary collecting ducts, not in the distal tubule, cortical collecting ducts, or outer medullary collecting ducts.