Urinary System
Instructions:
Select the single best answer to the numbered question.
Glomerular Filtration
Question # 1
Which of the following statements about glomerular filtration is NOT true?
A. The endothelium of the glomerular capillary is an important barrier to the passage of plasma proteins.
B. The glomerular basement membrane prevents the filtration of large plasma proteins.
C. The filtration slits between the podocytes help to retard the filtration of plasma proteins.
D. About 7 grams of albumin are filtered daily and reabsorbed by the proximal tubule.
E. Reducing the net negative charge on the components of the glomerular barrier will result in increased filtration of plasma proteins.
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Question # 2
Which of the following statements about glomerular filtration is NOT true?
A. The hydrostatic pressure drop across the glomerular capillary bed is small.
B. The oncotic pressure in capillary blood increases as blood flows through the glomerular capillary.
C. Increasing glomerular blood flow tends to increase glomerular filtration rate.
D. The filtration coefficient (Kf) of the glomerular capillaries is similar to that of most other capillary beds.
E. Contraction of mesangial cells may decrease the GFR by reducing Kf.
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Question # 3
A patient\'s GFR as measured from the inulin clearance is 125 ml/min. The patient\'s plasma creatinine is 0.01 mg/ml. The patient\'s urine flow rate is 1 ml/min and the concentration of creatinine in her urine is 1.35 mg/ml. Which of the following statements is not true?
A. The rate of filtration of creatinine is 1.25 mg/min
B. The clearance of creatinine is 125 ml/min.
C. The net rate of secretion of creatinine by the tubules is 0.1 mg/min.
D. The rate of creatinine excretion is 1.35 mg/min.
E. If the patient\'s plasma creatinine is in the steady state, the net rate of creatinine release from muscle and other cells is 1.35 mg/min.
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Question # 4
A patient\'s GFR is 125 ml/min and his plasma glucose is 4 mg/ml. The patient\'s urine flow rate is 2 ml/min and the concentration of glucose in his urine is 60 mg/ml. Which of the following statements is not true?
A. The rate at which glucose is filtered at the glomerulus is 500 mg/min.
B. The rate at which glucose is excreted is 120 mg/min.
C. The net rate of tubular reabsorption of glucose is 380 mg/min.
D. The highest plasma level for which all the filtered glucose could be reabsorbed is 2.5 mg/ml.
E. The renal function of this patient, so far as glucose is concerned, is normal.
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Question # 5
Which of the following statements about glomerular filtration is NOT correct?
A. The basal lamina (basement membrane) of the glomerular capillaries is the most important barrier to passage of plasma proteins.
B. If myoglobin is present in plasma, much of it will be filtered at the glomerulus.
C. Essentially no serum albumin is filtered, thus its daily filtered load is close to zero.
D. The filtration fraction is defined as GFR/RPF and it is normally between 0.15 and 0.20.
E. A disease that diminished the density of negative sialic acid moieties in the glomerular filtration barrier would result in greater filtration of plasma proteins.
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Question # 6
Which of the following statements about glomerular filtration is NOT correct?
A. The net filtration pressure in glomerular capillaries is not much different from that in other capillaries, but the filtration coefficient of the glomerulus is much greater than that of a typical capillary bed.
B. If the hydrostatic pressure in the glomerular capillary blood is 40 mm Hg, the capillary oncotic pressure is 25 mm Hg, and the hydrostatic pressure in Bowman\'s space is 15 mm Hg, then the net filtration pressure is zero.
C. Increasing renal blood flow will increase GFR , because when blood flow is increased the hydrostatic pressure decrease from the arterial end of the glomerular capillary to the venous end will be less.
D. Contraction of mesangial cells can decrease GFR by diminishing Kf (the filtration coefficient).
E. Dilation of the efferent arteriole should increase RPF, but should decrease GFR.
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Question # 7
Which of the following statements about the use of clearance methods to estimate GFR is NOT correct?
A. If 15% of the blood flow to a diseased kidney did not flow through the glomeruli, then the clearance of inulin would underestimate the true GFR by about 15%.
B. Creatinine clearance overestimates the GFR slightly due to secretion of creatinine in the proximal tubule.
C. If an individual with renal disease has a plasma creatinine of 3 mg/dl (1 mg/dl is normal), then that person\'s GFR is about 1/3 of the normal GFR.
D. If a substance is freely filtered at the glomerulus and is secreted and reabsorbed to the same extent (rate of secretion = rate of reabsorption), then its clearance would be a good estimate of GFR.
E. If a 70 kg person has a normal GFR and a plasma creatinine of 1 mg/dl, then that individual is expected to excrete creatinine at a rate of 1.25 mg/min, regardless of the urine flow rate.
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Question # 8
In a normal 70 kg human, we simultaneously measure the plasma levels of inulin and creatinine, the concentrations of inulin and creatinine in the urine, and the urine flow rate. Which of the following statements is NOT true?
A. The clearance of inulin will be about 125 ml/min.
B. The U/P ratio for inulin will be slightly less than the U/P for creatinine.
C. The GFR estimated from the creatinine clearance will be a slight overestimate of the actual GFR.
D. The clearance of creatinine will be slightly greater than the clearance of inulin.
E. We don\'t have enough information to estimate the net rate of creatinine absorption or secretion by the tubules.
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Question # 9
Which of the following statements about glomerular filtration is NOT true?
A. As blood flows through the glomerular capillaries, its hydrostatic pressure drops relatively little, but the plasma oncotic pressure rises significantly.
B. Anions are preferentially filtered over cations.
C. The glomerular basement membrane and rectangtular pores or slits in the membrane that bridges the processes of the podocytes may constitute the limiting barrier to large molecules.
D. At low renal blood flow rates, glomerular filtration rate may drop.
E. A small fraction of plasma protein is filtered into Bowman\'s Space.
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Question # 10
A person has a urine flow rate of 1 ml/min; plasma inulin = 8.33 mg/100ml; plasma creatinine = 2 mg/100ml; urine inulin = 10 mg/ml; urine creatinine = 2.6 mg/ml. Which of the following statements is not true?
A. The inulin clearance is 120 ml/min.
B. The creatinine clearance is 130 ml/min.
C. The rate of creatinine secretion is 0.1 mg/min.
D. The creatinine clearance overestimates the GFR by about 8.3%
E. The U/P ratio for creatinine is greater than that for inulin.
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Question # 11
Which of the following statements about the renal handling of creatinine and inulin is NOT true?
A. In humans, creatinine clearance is always greater than inulin clearance.
B. The inulin clearance of a 50 kg person should be about 90 ml/min.
C. Creatinine clearance in normal humans overestimates GFR by about 10%.
D. In a person with reduced GFR due to glomerular disease, but normal tubular function, creatinine clearance will overestimate GFR by a smaller fraction than in a normal individual.
E. The rate of creatinine secretion can be computed as the rate of creatinine excretion minus the filtered load of creatinine
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Question # 12
Which of the following statements about glomerular filtration is NOT true?
A. The capillary filtration coefficient of glomerular capillaries is 50 to 100 times greater than that of most other capillary beds.
B. The net filtration pressure is equal to the hydrostatic pressure in the glomerular capillary minus the hydrostatic pressure in Bowmanís space.
C. Increasing plasma flow rate in a glomerulus should tends to increase the overall rate of glomerular filtration in that glomerulus.
D. The net filtration pressure at the end of the glomerular capillary bed closest to the afferent arteriole is about 10 mm Hg.
E. The net filtration pressure diminishes as blood flows along the glomerular capillaries.
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Question # 13
Which of the following statements about control of GFR is NOT true?
A. An increase in the GFR in a particular nephron tends to increase the amount of salt and water reabsorbed from the proximal tubule of the same nephron.
B. The phenomenon described in A is partly due to decreased oncotic pressure and increased hydrostatic pressure in the peritubular capillaries of a nephron with increased GFR.
C. Increased flow rate in the macula densa of a nephron brings about diminished GFR in the glomerulus of the same nephron.
D. Contraction of mesangial cells may reduce GFR.
E. Renal disease may involve increased or decreased glomerular capillary permeability to macromolecules.
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Answer：
1.A 2.D 3.B 4.D 5.C 6.C 7.A 8.E 9.B 10.C
11.D 12.B 13.B
Renal Regulation of Acid-Base Balance
Question # 1
Which of the following statements about the role of the kidney in acid-base balance is NOT true?
A. About 50 to 100 mmole of H+ are excreted each day.
B. Renal compensation for an imbalance of the bodyas acid-base status is complete in approximately 6 hours.
C. Phosphate and ammonia are the major buffers of H+ in urine.
D. In an individual with normal plasma pH, the kidney reabsorbs essentially all filtered bicarbonate.
E. The kidney is responsible for net production of bicarbonate, which helps to compensate for depletion of bicarbonate stores due to respiratory loss of CO2.
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Question # 2
Which of the following statements about the role of the kidney in acid-base balance is NOT true?
A. Systemic acidosis promotes increased H+ secretion and bicarbonate reabsorption.
B. The titratable acidity of the urine is due mostly to H+ buffered by phosphate.
C. The capacity of the kidney to metabolize glutamine to ammonium and bicarbonate increases in response to acidosis.
D. The lower the pH of the fluid in the collecting duct, the greater its concentration of NH3 relative to the [NH3] in the medullary interstitium. This is called diffusional trapping of NH3.
E. The minimum pH of urine is about 4.
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Question # 3
Which of the following statements about the role of the kidney in acid-base balance is NOT correct?
A. In order to maintain homeostasis the net excretion of H+ by the kidney must be very close to the net metabolic production of nonvolatile acid.
B. In an individual in normal acid-base balance, greater than 99.5% of filtered bicarbonate is reabsorbed.
C. H+ that is secreted by the nephron accomplishes two things: reabsorption of bicarbonate and net excretion of H+.
D. The amount of H+ secreted in order to reabsorb bicarbonate is approximately equal to the net H+ excretion in the urine.
E. In an alkalotic individual a significant amount of bicarbonate is excreted in the urine.
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Question # 4
Which of the following statements about the role of the kidney in acid-base balance is NOT correct?
A. The thick ascending limb, by virtue of its high metabolic activity, is the major site of production of NH4+ from glutamine.
B. NH4+ is reabsorbed in the thick ascending limb.
C. NH4+ excretion will be enhanced, in a matter of hours, in an acidotic individual, due to increased diffusion trapping in the lower pH urine.
D. The kidney produces \"new\" bicarbonate, the reabsorption of which helps to maintain the body\'s store of bicarbonate for buffering.
E. Over several days, the kidney increases the levels of the enzymes that catabolize glutamine to NH4+.
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Question # 5
Which of the following statements about acid-base balance is NOT true?
A. Metabolically produced H+ is first buffered in the extracellular fluid, predominantly by bicarbonate.
B. As a consequence of buffering H+, carbon dioxide is blown off in the lungs. This reduces the total concentration of bicarbonate in the extracellular fluid.
C. The kidney reabsorbs more than 99% of filtered bicarbonate.
D. H+ secretion at the brush border membrane is responsible for reabsorbing filtered bicarbonate.
E. Excretion of each NH4+ ion in the urine represents the secretion of one H+, but has no effect on the bicarbonate stores in the extracellular fluid.
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Question # 6
Which of the following statements about acid-base balance is NOT true?
A. Titratable acid represents H+ bound to certain buffers, notably phosphate and NH4+, in the urine.
B. Titratable acidity is estimated by determining the amount of strong base that must be added to a known volume of urine to bring the pH to 7.4.
C. NH4+ in urine derives largely from NH4+ produced in renal tubular epithelial cells, largely from metabolism of glutamine.
D. The amount of NH4+ excreted in urine increases in acidosis.
E. H+ secretion by tubular epithelial cells plays a central role in formation of titratable acidity and in NH4+ excretion.
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Question # 7
Which of the following factors does NOT increase bicarbonate reabsorption?
A. Extracellular volume depletion.
B. Systemic acidosis.
C. Increase in glomerular filtration rate.
D. Decrease in plasma aldosterone levels.
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Question # 8
On a standard western diet, an individual produces 50-100 mEq of nonvolatile acids. Therefore, in order to stay in acid-base balance the kidney needs to perform the following essential functions EXCEPT:
A. Reabsorb nearly all of the filtered bicarbonate.
B. Generate new bicarbonate by excreting hydrogen ions with urinary buffers.
C. Reabsorb ammonium so that ammonium delivered to the liver can be converted into bicarbonate.
D. Extract glutamine from the systemic circulation in order to generate ammonium.
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Question # 9
Which of the the following statements about ammonium production IS true during metabolic acidosis?
A. Ammonium is synthesized by collecting duct cells.
B. Ammonium is synthesized and its excretion is regulated by systemic pH.
C. Because the filtered load of ammonium, urinary phosphate is the most important urinary buffer during metabolic acidosis.
D. Ammonium production decreases in response to systemic acidosis.
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Answer：
1.B 2.D 3.D 4.A 5.E 6.A 7.D 8.C 9.B
Tubular Function
Question # 1
Which of the following statements about the proximal tubule is NOT true?
A. About two-thirds of filtered water and NaCl are reabsorbed there.
B. Most of the filtered bicarbonate is reabsobed there.
C. Several organic acids and bases are secreted by the second half of the proximal tubule.
D. Carbonic anhydrase aids in the reabsorption of filtered chloride and bicarbonate.
E. Significant flux of water and ions occurs via the paracellular pathway.
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Question # 2
Which of the following statements about the thick ascending limb (TAL) is NOT true?
A. The Na,K,2Cl transporter in the luminal membrane plays a central role in active reabsorption of NaCl.
B. The TAL is the first place in the nephron where fluid becomes hypotonic to plasma.
C. The Na,K-ATPase is the only primary active transporter.
D. Significant reabsorption of bicarbonate occurs.
E. The epithelium is highly impermeable to water, but significantly permeable to NaCl.
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Question # 3
Which of the following statements about the distal tubule and collecting duct is NOT true?
A. In the first part of the distal tubule NaCl is reabsorbed and the fluid can approach 100 milliosmoles/liter.
B. The water permeability of the first part of the distal tubule is regulated by ADH.
C. Principal cells can secrete K+.
D. Intercalated cells secrete H+ and actively take up K+.
E. Osmolarity at beginning of the collecting duct varies from hypo- to isotonic relative to plasma.
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Question # 4
Which of the following statements about the proximal tubular transport processes is NOT correct?
A. About 2/3 of water and NaCl filtered are reabsorbed in the proximal tubule.
B. In the first part of the proximal tubule the amounts of bicarbonate and Cl- reabsorbed are roughly equal.
C. Secretion of organic anions and cations occurs mostly in the second part of the proximal tubule.
D. The Na/H exchanger in the luminal membrane plays a central role in the reabsorption of bicarbonate.
E. The reabsorption of glucose and amino acids promotes the reabsorption of NaCl and water in the first part of the proximal tubule.
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Question # 5
Which of the following statements about ion transport processes in the kidney is NOT correct?
A. In the thick ascending limb (TAL) the active reabsorption of Cl- is mediated by the combined action of Na/K/2Cl transporters in the luminal membrane and electrogenic Cl- channels in the basolateral membrane.
B. Loop diuretics block the basolateral Cl- channels in the TAL.
C. In the late distal tubule and the collecting duct there are two different cell types with different transport processes: principal cells and intercalated cells.
D. Intercalated cells secrete H+ into the lumen and play an important role in acid-base balance.
E. The late distal tubule and collecting duct can either secrete K+ or reabsorb K+ in the net sense.
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Question # 6
Which of the following statements about renal handling of glucose in a 70 kg person with normal GFR is NOT correct?
A. The kidney does not participate in regulating the normal plasma glucose level.
B. If plasma glucose is 1 mg/ml, the filtered load of glucose is about 80 mg/min.
C. If we administer a drug that completely blocks glucose reabsorption, then at a plasma glucose of 1 mg/ml, glucose clearance would be about 125 ml/min.
D. If glucose begins to appear in the urine at a plasma glucose of 3.5 mg/ml, then the Tm for glucose is about 440 mg/min.
E. If the plasma glucose is 4 mg/ml and the Tm is 440 mg/min, then the glucose clearance is 15 ml/min.
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Question # 7
Which of the following statements about reabsorption in the proximal tubule is NOT true?
A. Gradient-time behavior is characteristic of solutes with high passive permeability.
B. Parathyroid hormone decreases the Tm for phosphate reabsorption.
C. In the presence of parathyroid hormone, the plasma level of phosphate tends to decrease.
D. In gout, the Tm for uric acid reabsorption is increased.
E. The rate of uric acid (ura) reabsorption is equal to (Uura V) - GFR.
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Question # 8
Which of the following statements about the renal handling of para-amino hippuric acid (PAH) is NOT true?
A. The clearance of PAH is a slight over-estimate of renal plasma flow.
B. The true rate of renal plasma flow is equal to UpahV divided by the arteriovenous PAH concentration difference.
C. For any substance (x) subject to net secretion, we can, in principle, estimate renal plasma flow from UxV divided by the A-V concentration difference for x across the kidney.
D. The rate of PAH secretion can be estimated from: UpahV - CinulinPpah, where C denotes clearance.
E. PAH in blood flowing in the vasa recta does not have all the PAH from it secreted into the urine.
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Question # 9
Which of the following statements about the handling of ions and water in the proximal tubule is NOT true?
A. The amount of Na+ reabsorbed is proportional to the GFR.
B. Normally about 2/3 of the Na+ filtered is reabsorbed.
C. The fraction of filtered Na+ reabsorbed is normally close to the fraction of filtered water reabsorbed.
D. The fraction of filtered Na+ reabsorbed is appreciably smaller than the fraction of Cl- reabsorbed.
E. In the presence of an osmotic diuretic the fraction of filtered Na+ reabsorbed is greater than the fraction of filtered water reabsorbed.
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Question # 10
A patient has GFR = 120 ml/min and urine flow of 1 ml/min. The plasma [K+] = 4.5 mM and urine [K+] = 50 mM. The plasma [Na+] = 140 mM and urine [Na+] = 75 mM.
A. The clearance of K+ is 11.1 ml/min.
B. The net rate of K+ secretion is 0.49 mmole/min.
C. The clearance of Na+ is 0.536 ml/min.
D. The rate of Na+ reabsorption is 16.73 mmole/min.
E. The fraction of filtered Na+ being excreted is 0.004.
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Question # 11
In an individual whose plasma [glucose] is 1 mg/ml, which of the following statements about renal handling of glucose is NOT true?
A. Splay in the threshold value of plasma glucose at which glucose first appears in the urine is due to the fact that not all blood perfusing the kidney supplies the proximal tubules.
B. The Tm for glucose in a normal individual is about 3 times greater than the filtered load of glucose.
C. The Tm for glucose is normally about 375 mg/min.
D. A patient with renal disease has a GFR that is reduced by 20% from normal, but has normal tubular function. The threshold plasma glucose concentration for the appearance of glucose in the urine of this patient will be about 3.75 mg/ml.
E. In a normal individual the kidney does not play a role in regulatory mechanisms that maintain plasma glucose levels within the normal range.
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Question # 12
Which of the following statements about the function of the proximal tubules is NOT true?
A. About 2/3 of filtered Na+, Cl-, K+, and water is typically reabsorbed in the proximal tubule.
B. Acidification of the luminal fluid, via the Na+/H+ exchanger, is responsible for much of the reabsorption of bicarbonate that occurs in the first half of the proximal tubule.
C. The first half the proximal tubule is the site of the most active reabsorption of glucose and amino acids.
D. The greatest fraction of Cl- reabsorption occurs in first half of the proximal tubule.
E. Carbonic anhydrase on the luminal surface of the brush border of the early proximal tubule plays an important role in bicarbonate reabsorption.
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Question # 13
Which of the following statements about tubular function is NOT true?
A. In a person in neutral fluid balance, there is net reabsorption of water in the proximal tubule, the distal tubule, the loop of Henle, and the collecting duct.
B. In the thick ascending limb (TAL), Na+, Cl- and certain other ions are reabsorbed.
C. Tubular fluid at the beginning of the distal tubule fluid is typically isotonic to plasma.
D. Partly due to the presence of H+,K+-ATPase in the luminal plasma membrane, intercalated cells reabsorb K+ and secrete H+.
E. Reabsorption of Na+ and Cl- occurs in the collecting ducts.
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Answer：
1.D 2.E 3.B 4.B 5.B 6.B 7.E 8.A 9.D 10.B
11.A 12.D 13.C
Renal Blood Flow
Question # 1
Which of the following statements about autoregulation of renal blood flow and GFR is NOT true?
A. Both renal blood flow and GFR tend to remain constant in the face of changes in mean arterial pressure from 90 to 180 mm Hg.
B. The myogenic mechanism contributes to autoregulation.
C. The renal nerves play an important role in autoregulation.
D. Tubuloglomerular feedback involving the juxtaglomerular apparatus brings about decreased renal blood flow and decreased GFR in response to an increased rate of fluid flow in the macula densa.
E. The myogenic mechanism depends on the contraction of the afferent arteriole in response to increased pressure and its relaxation in response to decreased arterial pressure.
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Question # 2
Which of the following statements about estimates of renal blood flow is NOT true?
A. The clearance of PAH is always an underestimate of the true renal plasma flow.
B. The true renal plasma flow is equal to the rate of excretion of PAH divided by the arterio-venous plasma concentration difference for PAH.
C. Increasing the plasma concentration of PAH will cause the PAH clearance to be a better estimate of renal plasma flow.
D. Renal blood flow is equal to renal plasma flow divided by (1-hematocrit).
E. Renal plasma flow in a 70 kg person is about 700 ml/min.
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Question # 3
Which of the following statements about regulation of GFR and renal blood flow (RBF) is NOT correct?
A. GFR and RBF tend to remain constant despite significant changes in arterial blood pressure.
B. The phenomenon described in A is called autoregulation. Autoregulation does not depend on the function of the renal sympathetic nerves.
C. The myogenic mechanism contributes to autoregulation: when the afferent arterioles experience elevated pressure, they contract in response.
D. The juxtaglomerular apparatus plays a role in autoregulation: increased delivery of NaCl to the macula densa leads to relaxation of the afferent arteriole.
E. Constriction of the efferent arteriole is expected to increase GFR and to decrease RBF.
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Question # 4
Which of the following statements about renal handling of PAH is NOT correct?
A. One reason that the clearance of PAH can never be a perfect estimate of renal plasma flow (RPF) is that some of the blood that perfuses the kidney does not flow through the peritubular capillaries.
B. For the reason expressed in A, even if we were to measure the level of PAH in blood in the renal artery and the renal vein, and were to compute the renal plasma flow as the rate of PAH excretion divided by the arterio-venous difference plasma PAH concentration, this quantity would underestimate the true renal plasma flow.
C. If the plasma level of PAH is increased so that the proximal tubule can no longer secrete all the PAH present in the peritubular blood, then the PAH clearance will seriously underestimate renal plasma flow.
D. Renal blood flow = RPF/(1 - hematocrit)
E. The normal renal plasma flow in a 70 kg person is about 700 ml/min.
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Question # 5
Which of the following statements is NOT true?
A. Both renal blood flow and GFR tend to remain fairly constant in the face of significant increases or decreases in arterial blood pressure. This is known as autoregulation of GFR and RPF.
B. The sympathetic innervation of the glomerular arterioles are not required for autoregulation of GFR and RPF.
C. Autoregulation of GFR and RPF in response to an increase in blood pressure must involve constriction of the afferent arteriole.
D. Autoregulation of GFR and RPF in response to a decrease in arterial pressure must involve constriction of the efferent arteriole.
E. None of the above.
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Question # 6
Which of the following statements about renal handling of PAH (para-aminohippuric acid) is NOT true?
A. The clearance of PAH in a normal human is about 5 times the GFR.
B. PAH clearance underestimates true renal plasma flow (RPF) by about 10%.
C. The renal plasma flow, computed as the rate of excretion of PAH divided by the difference in PAH concentration between renal arterial plasma and renal venous plasma, will underestimate true renal plasma flow.
D. The filtration fraction in a normal human is between 0.15 and 0.2.
E. Increasing the plasma concentration of PAH may cause the PAH clearance to be a greater underestimate of true renal plasma flow.
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Question # 7
Which of the following statements about regulation of GFR and renal blood flow (RBF) is NOT true?
A. RBF and GFR tend to remain rather constant in the face of marked changes in mean arterial pressure. This is called autoregulation.
B. The myogenic mechanism contributes to autoregulation of RBF, but not to autoregulation of GFR.
C. If increased GFR in a particular nephron leads to increased rate of fluid flow in the macula densa of that nephron, then the macula densa does something that results in constriction of the afferent arteriole of that same nephron.
D. A decrease in arterial blood pressure tends to lead to relaxation of afferent arterioles.
E. An increased resistance of the afferent arterioles with a similar decrease in resistance of the efferent arterioles should lead to diminished GFR with little change in RBF.
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Answer：
1.C 2.C 3.D 4.D 5.D 6.C 7.B
Production of Concentrated and Diluted Urine
Question # 1
Which of the following statements about the production of concentrated urine is NOT true?
A. The accumulation of NaCl in the medullary interstitium depends on the active reabsorption of NaCl by the thick ascending limb.
B. Countercurrent multiplication in the vasa recta helps to prevent washout of the medullary gradients of NaCl and urea.
C. In the presence of ADH urea is reabsorbed from the inner medullary collecting ducts.
D. The descending limb of the loop of Henle is permeable to water.
E. In the presence of high levels of ADH, about 50% of the osmolality of the interstitum of the inner medulla is due to NaCl.
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Question # 2
Which of the following statements about the renal concentrating mechanism is NOT correct?
A. The active reabsorption of NaCl in the thick ascending limb is known as the single effect.
B. The TAL can create a gradient of NaCl between tubular fluid and medullary interstitium of about 200 mosmolal at a given depth in the medulla.
C. As fluid descends in the descending limb, water is osmotically withdrawn and NaCl in the tubular fluid becomes concentrated.
D. As fluid ascends in the thin ascending limb, Na+ and Cl- are passively reabsorbed.
E. Fluid leaving the TAL is approximately iso-osmotic to plasma.
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Question # 3
Which of the following statements about the renal concentrating mechanism is NOT correct?
A. In the presence of ADH, fluid in the later part of the distal tubule and the cortical collecting duct is hypo-osmotic with respect to plasma.
B. In the presence of ADH, urea is reabsorbed from the inner medullary collecting duct and accumulates there to a level of approximately 600 mM.
C. In the absence of ADH, the level of urea in the inner medullary interstitium declines.
D. The total solute excretion rate tends to remain relatively constant in the face of large changes in urine volume and urine osmolality.
E. In the absence of ADH, the osmolality of urine is less than the osmolality of fluid in the cortical collecting duct.
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Question # 4
Which of the following statements about the concentration of Na+ in the tubular fluid is NOT true?
A. In the proximal tubule, it is normally approximately equal to that in plasma.
B. In the thick ascending limb of Henle, it is normally less than that in plasma.
C. In the first part of the distal tubule, Na+ concentration is equal to that in plasma when ADH is present.
D. In the absence of ADH, Na+ concentration in the beginning of the collecting duct is less than that in plasma.
E. In the absence of ADH, Na+ concentration falls as fluid progresses down the collecting duct.
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Question # 5
Which of the following statements about ADH is NOT true?
A. Osmoreceptors in the supraoptic and paraventricular nuclei respond to hypertonicity by increasing ADH release.
B. Alcohol causes diuresis by inhibiting ADH release.
C. Hyperosmolality stimulates both ADH release and thirst.
D. ADH inhibits the action of aldosterone to promote salt and water reabsorption in the distal tubule.
E. ADH increases the water permeability of the lumenal membrane of the later part of the distal tubule and the collecting duct by causing more water channel proteins to be inserted in these membranes.
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Question # 6
Which of the following statements about the urine concentrating mechanism in the renal medulla is NOT true?
A. The thick ascending limb actively reabsorbs Na+ to produce the single effect Cl- follows to preserve electroneutrality.
B. The water permeability of the descending limb is higher than that of the ascending limb.
C. The deeper in the medulla, the higher the NaCl concentration.
D. In the presence of ADH the total osmolality of the interstitial fluid near the tip of the renal papilla is reduced.
E. Animals with longer loops of Henle can produce more concentrated urine.
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Question # 7
Which of the following statements about renal handling of urea is NOT true?
A. Urea deposited in the inner medulla plays a role in the mechanism by which the kidney produces hyperosmotic urine.
B. Urea reabsorbed in the inner medullary collecting ducts enters the tubular fluid in the loops of Henle.
C. In the presence of ADH, urea is concentrated in the late distal tubule and the cortical collecting ducts when water is absorbed there.
D. In the absence of ADH, there is less deposition of urea in the inner medulla.
E. When there is a high flow rate in the inner medullary collecting ducts, there is a high rate of urea reabsorption there.
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Question # 8
Which of the following statements about production of concentrated and dilute urine is NOT true?
A. The range of osmolality of urine that a normal human can produce is from 50 mosmoles/liter with no ADH to 1200 mosmoles/liter with maximal levels of ADH.
B. The ability to produce a concentrated urine, but not the ability to produce a dilute urine, depends on the reabsorption of NaCl by the thick ascending limb of the loop of Henle (the TAL).
C. Countercurrent multiplication of NaCl, but not urea, occurs in the loop of Henle.
D. Deposition of urea in the interstitium of the inner medulla depends on the presence of ADH.
E. In the presence of maximal ADH, the osmolality of NaCl in the inner medullary interstitium is about equal to the osmolality of urea there.
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Question # 9
Which of the following statements of diuretics is NOT true?
A. Osmotic diuretics result in increased reabsorption of NaCl by the thick ascending limb (TAL).
B. Carbonic anhydrase inhibitors may contribute to metabolic acidosis.
C. The target of loop diuretics is the reabsorption of Na+ by the electrogenic Na+ channels in the luminal plasma membrane of the TAL.
D. Potassium sparing diuretics decrease Na+ transport across the luminal plasma membranes of principal cells of the late distal tubule and collecting duct.
E. Potassium sparing diuretics do not produce a large increase in urine flow rate.
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Answer：
1.B 2.E 3.A 4.C 5.D 6.A 7.E 8.B 9.C
Regulation of the Volume and Osmolality of Extracellular Fluid
Question # 1
Which of the following statements about the responses to depleted extracellular fluid volume is NOT true?
A. Increased activity in renal sympathetic nerves will result in decreased GFR and increased NaCl reabsorption in proximal tubule.
B. If the volume depletion is large, ADH release will be decreased.
C. Renin will be released due to decreased pressure in afferent arterioles and decreased delivery of NaCl to the macula densa.
D. Angiotensin II levels will rise, enhancing thirst and increasing NaCl reabsorption in the proximal tubule.
E. Level of atrial natriuretic peptide will decrease.
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Question # 2
Which of the following statements about the responses to expanded extracellular volume is NOT true?
A. Decreased activity in renal sympathetic nerves will result in increased GFR and decreased reabsorption of NaCl in proximal tubule.
B. Increased levels of atrial natriuretic peptide will stimulate reabsorption of NaCl in collecting ducts.
C. Decreased levels renin will be released, leading to diminished levels of angiotensin II.
D. Decreased release of aldosterone from the adrenal cortex will result in less reabsorption of NaCl in distal tubule and collecting duct.
E. The diminished angiotensin II levels will contribute to less reabsorption of NaCl by the proximal tubule.
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Question # 3
Which of the following statements about regulation of plasma osmolality is NOT true?
A. Urine volume can vary from about 0.5 to 20 liters/day, while urine osmolality can vary from about 50 mosmolal to 2500 mosmolal.
B. Total solute excretion (mosmoles/unit time) tends to remain constant in the face of large changes in volume and osmolality.
C. ADH release is much more sensitive to changes in the osmolality of extracellular fluid than to changes in extracellular fluid volume.
D. In a patient with expanded extracellular volume, ADH release in response to an increase in osmolality is decreased (relative to an individual with normal ECF volume).
E. In a volume-expanded individual the release of ADH is suppressed via neural reflexes.
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Question # 4
Which of the following statements about the renal regulation of extracellular fluid (ECF) volume is NOT correct?
A. In a volume depleted individual, increased reabsorption of Na+ in Henle\'s loop is brought about by increased levels of aldosterone and ADH.
B. In response to decreased extracellular fluid volume, more NaCl is reabsorbed in the collecting ducts. This effect is promoted by elevated levels of aldosterone.
C. In response to expansion of the extracellular fluid volume, levels of renin and ADH in the circulation decrease.
D. In response to expansion of the extracellular fluid volume, impulse traffic in sympathetic nerves to the kidney increases.
E. In response to expansion of extracellular fluid volume, less reabsorption of Na+ occurs in the proximal tubule.
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Question # 5
Which of the following statements about responses to decreased extracellular volume is NOT correct?
A. There are decreased levels of ANP, hence increased reabsorption of Na+ in the collecting duct.
B. There is increased impulse traffic in renal sympathetic nerves and hence decreased GFR.
C. There are increased levels of aldosterone and hence increased reabsorption of Na+ in the proximal tubule.
D. There is an increase in ADH and hence production of a small volume of urine with high osmolality.
E. There will be increased levels of angiotensin II and hence increased reabsorption of Na+ in the proximal tubule.
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Question # 6
Which of the following statements control of the osmolality of body fluids NOT correct?
A. ADH is the only major regulator of urine osmolality.
B. The maximal osmolality of urine is about 1200 mosmolal.
C. ADH is released in response to increased osmolality of extracellular fluid.
D. ADH is released in response to depletion of the volume of the extracellular fluid.
E. The release of ADH is about as sensitive to changes in ECF osmolality as to changes in ECF volume.
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Question # 7
Which of the following statements about regulation of salt and water reabsorption in the proximal tubule is NOT correct?
A. When GFR in a single nephron increases at constant plasma flow, the oncotic pressure in the peritubular capillary increases. This promotes increased reabsorption of salt and water from the proximal tubule of that same nephron.
B. When GFR in a single nephron increases at constant plasma flow, the hydrostatic pressure in the peritubular capillary increases. This promotes increased reabsorption of salt and water from the proximal tubule of that same nephron.
C. When GFR increases, the filtered load of glucose and amino acids increases. This tends to promote increased reabsorption of salt and water in the proximal tubule.
D. Angiotensin II increases NaCl reabsorption in the proximal tubule.
E. Activity in sympathetic nerves stimulates NaCl reabsorption in the proximal tubule.
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Question # 8
Which of the following statements about ADH is NOT true?
A. Hyperosmolality in the supraoptic nuclei causes ADH release from the posterior pituitary.
B. Increased pulse pressure causes decreased ADH release from the posterior pituitary.
C. Stretch of the left atrium causes decreased release of ADH.
D. Increased ADH induces the sensation of thirst.
E. ADH increases the permeability of the collecting ducts to water and Na+.
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Question # 9
A patient has urinary osmolality of 50 mOsm/L, a urine flow rate of 15 ml/min, and a plasma osmolality of 300 mOsm/L. Which of the following statements about this patient is NOT true?
A. The patient is in pronounced diuresis.
B. The patient\'s osmolar clearance is 2.5 ml/min.
C. The patient\'s free water clearance is 12.5 ml/min.
D. The osmotically active solute in the patient\'s urine each minute is equal to that in 2.5 ml of plasma.
E. The patient is excreting 750 mosmoles of solute each minute.
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Question # 10
Which of the following statements about regulation of osmolality is NOT true?
A. Osmolar clearance is equal to urine osmolality times urine flow rate divided by plasma osmolality.
B. Free water clearance is equal to urine flow rate minus osmolar clearance.
C. Osmolar clearance tends to remain constant in the face of changes in urine flow rate.
D. In the absence of ADH, free water clearance tends to be positive and large.
E. A free water clearance of negative 1.5 ml/min means that the effect on total body osmolality is equivalent to the addition to the extracellular space of 1.5 ml of isotonic saline per minute.
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Question # 11
A patient complains of several days of vomiting and diarrhea and is found to have a reduced effective circulating volume that activates the sympathetic nervous system. In this case, activation of the sympathetic nervous system reduces sodium excretion by the following mechanisms EXCEPT:
A. Decreases glomerular hydrostatic pressure by increasing afferent arteriolar constriction.
B. Increases renin secretion leading to an increase in plasma angiotensin II and aldosterone levels.
C. Indirectly increases proximal tubule sodium reabsorption through the action of aldosterone on proximal tubule cells.
D. Directly increases reabsorption of sodium by the proximal tubule and loop of Henle.
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Question # 12
In response to an expanded effective circulating volume, atrial natriuretic peptide is released from the cardiac atria to promote sodium excretion by the following mechanisms EXCEPT:
A. Increased glomerular filtration rate by dilating afferent arterioles.
B. Decreased sodium reabsorption by the collecting duct cells.
C. Decreased aldosterone secretion by the adrenal cortex.
D. Decreased NaCl transport by the thick ascending limb.
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Question # 13
Which of the following statements about regulation of plasma osmolality is NOT true:
A. ADH release is influenced by nonosmotic stimuli including blood volume and certain medications.
B. ADH release is more sensitive to changes in plasma osmolality than to changes in effective circulating volume
C. Urine volume can vary between 0.5 to 20 L/day in a normal individual.
D. Regulation of ADH release and perception of thirst work together to maintain plasma osmolality.
E. Total solute excretion is highly dependent on the urine flow rate.
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Answer：
1.B 2.B 3.A 4.D 5.C 6.E 7.B 8.E 9.E 10.E
11.C 12.D 13.E |
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