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First Aid for the® USMLE Step 1 2011 EXPRESS workbook page 165
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
Renal
ANATOMY
1. Why is the left kidney harvested for transplantation rather than the right? (p. 458) _____________
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2. Ureters pass __________ (over/under) the uterine artery and the ductus deferens. (p. 458)
PHYSIOLOGY
3. Extracellular fluid consists of __________ (high/low) sodium chloride and __________ (high/low) potassium, whereas intracellular fluid consists of __________ (high/low) sodium chloride and __________ (high/low) potassium. (p. 459)
4. What is the 60-40-20 rule of total body weight? (p. 459) __________________________________
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5. The fenestrated capillary endothelium of the glomerular filtration barrier is responsible for the filtration of plasma by which characteristic: size or charge? (p. 459) _________________________
6. The fused basement membrane of the glomerulus containing heparan sulfate is responsible for the filtration of plasma molecules by which characteristic, size or charge? (p. 459) ________________
7. The epithelial layer of the glomerular filtration barrier is formed by which cells? (p. 459) _________
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8. What is the formula for calculating the clearance of substance X, the volume of plasma from which the substance is cleared completely per unit of time? (p. 459) _____________________________
9. If renal clearance is greater than the glomerular filtration rate (GFR) of substance X, then there is a net tubular __________ (reabsorption/secretion) of substance X. (p. 459)
10. Creatinine clearance slightly __________ (overestimates/underestimates) the GFR rate because creatinine is __________ (secreted/reabsorbed) by the renal tubules. (p. 459)
11. What is the formula for estimating renal blood flow if renal plasma flow is known? (p. 459) ______
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12. What are the effects of prostaglandins on the glomerulus? (p. 460) ________________________
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Questions
page 166 First Aid for the® USMLE Step 1 2011 EXPRESS workbook
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
13. What are the effects of angiotensin II on the glomerulus? (p. 460) __________________________
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14. Decreased plasma protein concentration causes __________ (decrease/increase/no change) in renal plasma flow and __________ (decrease/increase/no change) in GFR, which in turn results in __________ (decrease/increase/no change) in the filtration fraction. (p. 460)
15. Constriction of the afferent arteriole causes __________ (decrease/increase/no change) in renal plasma flow and __________ (decrease/increase/no change) in GFR, which in turn results in __________ (decrease/increase/no change) in the filtration fraction. (p. 460)
16. What is the formula for excretion rate? (p. 460) _________________________________________
17. In the nephron, glucose at normal plasma concentrations is reabsorbed in which structure? And by which transporter? (p. 460) ________________________________________________________
18. At what plasma glucose concentration is the transport mechanism of the proximal tubule completely saturated, leading to glucose spilling into the urine? (p. 460) _____________________
19. How and where are amino acids reabsorbed in the kidney? (p. 460) ________________________
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20. What substance is secreted into the lumen of the early proximal convoluted tubule and acts as a buffer for hydrogen ions? (p. 461) ___________________________________________________
21. Which two ions are actively reabsorbed in the thick ascending loop of Henle? (p. 461) _________
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22. Which three ions are indirectly reabsorbed in the thick ascending loop of Henle? (p. 461) ________
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23. Which hormone controls the reabsorption of calcium in the early distal convoluted tubule? (p. 461) ______________________________________________________________________________
24. On which segment of the nephron does the hormone aldosterone act? (p. 461) _______________
25. ADH’s effect at V2 receptors results in what action? (p. 461) _______________________________
26. The ratio of solute concentration in the tubular fluid versus plasma (TF/P) can indicate the level of secretion or reabsorption of that solute along the proximal renal tubule. If the TF/P ratio of that solute is less than that of inulin, there is net __________ (reabsorption/secretion) along the proximal tubule. (p. 462)
27. Along the length of the proximal tubule, does the relative concentration of chloride increase, decrease, or stay the same? (p. 462) _________________________________________________
28. Which five actions of angiotensin II serve to increase intravascular volume and blood pressure? (p. 462) __________________________________________________________________________
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First Aid for the® USMLE Step 1 2011 EXPRESS workbook page 167
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
29. What is the site of action of angiotensin-converting enzyme? (p. 462) _______________________
30. When blood pressure falls, the kidneys release which proteolytic enzyme? (p. 462) ____________
31. ADH primarily regulates __________ (osmolarity/blood volume), whereas aldosterone primarily regulates __________ (osmolarity/blood volume). However, in __________ (low/high) volume states, both ADH and aldosterone act to protect __________ (osmolarity/blood volume). (p. 462)
32. What are the effects of aldosterone secretion? (p. 462) __________________________________
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33. Atrial natriuretic peptide __________ (decreases/increases) renin secretion and __________ (decreases/increases) the GFR. (p. 462)
34. Which cells produce renin in the kidney? (p. 463) _______________________________________
35. Which hormone is released by the endothelial cells of renal peritubular capillaries in response to hypoxia? (p. 463) ________________________________________________________________
36. Which enzyme from the kidney is activated by PTH, and what is the function of that enzyme? (p. 463) __________________________________________________________________________
37. In the chart below, checkmark the effect that each condition has on the potassium shift. (p. 464)
Effect Shifts K
+ Into Cell
Hypokalemia Shifts K
+ Out of Cell
Hyperkalemia
Acidosis
Alkalosis
β-Adrenergic agonists
β-Adrenergic antagonists
Cell lysis
Digitalis
Hyperosmolarity
Hypo-osmolarity
Insulin
Insulin deficiency
38. By which mechanism does digitalis cause hyperkalemia? (p. 464) __________________________
39. What is the primary electrolyte disturbance in metabolic acidosis? (p. 465) ___________________
40. What is the compensatory respiratory response to metabolic acidosis, and does PCO2 increase or decrease? (p. 465) _______________________________________________________________
41. What are the ten causes of increased anion gap metabolic acidosis? (p. 465) ________________
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page 168 First Aid for the® USMLE Step 1 2011 EXPRESS workbook
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
PATHOLOGY
42. What four clinical findings are associated with nephritic syndrome? (p. 467) __________________
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43. Match the nephritic syndrome with its characteristic finding on light microscopy. (p. 467)
_____ A. Acute poststreptococcal glomerulonephritis 1. Crescent-shaped scars _____ B. Alport’s syndrome 2. Immune complexes in mesangium _____ C. Diffuse proliferative glomerulonephritis 3. “Lumps and bumps” _____ D. IgA glomerulopathy 4. Split basement membrane _____ E. Rapidly progressive glomerulonephritis 5. “Wire looping” of capillaries
44. A 10-year-old boy presents with swollen ankles and periorbital edema, which were beginning to resolve without intervention. Electron microscopy of a kidney biopsy specimen shows subepithelial immune complex humps. Which form of nephritic syndrome does he most likely have? (p. 467) ___
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45. Wegener's granulomatosis is __________ (c-ANCA/p-ANCA) positive, whereas microscopic polyarteritis is __________ (c-ANCA/p-ANCA) positive. (p. 467)
46. For which systemic disease is diffuse proliferative glomerulonephritis the most common cause of death? (p. 467) __________________________________________________________________
47. What four clinical findings are associated with nephrotic syndrome? (p. 468) __________________
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48. Match the nephrotic syndrome with its characteristic findings. (p. 468)
_____ A. Amyloidosis 1. Associated with chronic disease _____ B. Diabetic glomerulonephropathy 2. Foot process effacement on EM _____ C. Focal segmental glomerulosclerosis 3. Hyalinosis on LM _____ D. Membranous glomerulonephritis 4. Kimmelstiel-Wilson lesion on LM _____ E. Membranoproliferative glomerulonephritis 5. Spike-and-dome appearance on EM _____ F. Minimal change disease 6. Tram-track appearance on EM
49. What is the most common glomerular disease seen in patients with HIV? (p. 468) ______________
50. In diabetic glomerulonephropathy, what causes mesangial expansion? (p. 468) _______________
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51. Kidney stones are most commonly composed of what element? (p. 469) _____________________
52. Both antifreeze and vitamin C abuse can result in the formation of which type of crystals? (p. 469) _
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53. An 80-year-old man with leukemia presents with hematuria and right-sided flank pain. Which type of kidney stone is he most likely to have? And how would this stone appear on x-ray? (p. 469) ______________________________________________________________________________
54. Name the four components of the WAGR complex. (p. 469) _______________________________
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First Aid for the® USMLE Step 1 2011 EXPRESS workbook page 169
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
55. Match the renal pathology with its characteristic findings. (pp. 469-472)
_____ A. Acute pyelonephritis 1. Associated with aniline dye exposure _____ B. Acute tubular necrosis 2. Associated with diabetes _____ C. Bladder cancer 3. Associated with obstetric catastrophe _____ D. Chronic pyelonephritis 4. Associated with vHL syndrome _____ E. Diffuse cortical necrosis 5. Muddy brown casts in urine _____ F. Drug-induced interstitial nephritis 6. Nephroblastoma _____ G. Renal cell carcinoma 7. Painless hematuria _____ H. Renal papillary necrosis 8. Pyuria and azotemia _____ I. Transitional cell carcinoma 9. Thyroidization of kidney _____ J. Wilms’ tumor 10. WBC casts in urine
56. What are three causes of acute tubular necrosis? (p. 470) ________________________________
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57. Which three general types of renal dysfunction can lead to acute renal failure? (p. 471) _________
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58. True or False: Unilateral postrenal outflow obstruction can lead to acute renal failure. (p. 471) ____
59. A patient's urine osmolarity is <350 mOsm/L, urine sodium level is >40 mEq/L, fractional excretion of sodium is >4%, and BUN/creatinine ratio is >15:1. Is the etiology of the acute renal failure most likely to be prerenal, renal, or postrenal? (p. 471) _______________________________________
60. A patient’s urine osmolarity is >500 mOsm/L, urine sodium level is <10 mEq/L, fractional excretion of sodium is <1%, and BUN/creatinine ratio is >20:1. Is the etiology of the acute renal failure most likely to be prerenal, renal, or postrenal? (p. 471) _______________________________________
61. What are the eight consequences of renal failure? (p. 471) ________________________________
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62. Which type of mutation causes autosomal-dominant polycystic kidney disease (formerly adult polycystic kidney disease)? (p. 472) _________________________________________________
63. What are the two major causes of death associated with autosomal-dominant polycystic kidney disease? (p. 472) ________________________________________________________________
64. What are the complications of autosomal-recessive polycystic kidney disease in utero and after the neonatal period? (p. 472) __________________________________________________________
PHARMACOLOGY
65. What is the mechanism of action of acetazolamide? (p. 474) ______________________________
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66. What is the mechanism of action of furosemide? (p. 474) _________________________________
67. Which loop diuretic is used for diuresis of patients who are allergic to sulfa drugs? (p. 474) ______
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page 170 First Aid for the® USMLE Step 1 2011 EXPRESS workbook
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
68. What are the effects of hydrochlorothiazide toxicity? (p. 474) _____________________________
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69. What is the mechanism of action of spironolactone? (p. 475) ______________________________
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70. What is the mechanism by which ACE inhibitors can cause angioedema? (p. 475) _____________
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71. What are three clinical uses of ACE inhibitors? (p. 475) __________________________________
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ANATOMY
1. Because the left kidney has a longer renal vein.
2. Under. (Remember: "water [ureters] under the bridge [artery and ductus deferens]")
PHYSIOLOGY
3. High; low; low; high. (Remember: HIKIN': HIgh K Intracellular.)
4. 60% of total body weight is made up of total body water, 40% is made up of intracellular fluid, and 20% is made up of extracellular fluid.
5. Size.
6. Net charge.
7. Podocyte foot processes.
8. Renal clearance of X = the urine concentration of X times the urine flow rate, divided by the plasma concentration of X (Cx = Ux × V/Px).
9. Secretion.
10. Overestimates; secreted. (The plasma concentration of creatinine is slightly lower than it would be from filtration alone.)
11. Renal blood flow = renal plasma flow divided by (1 - the hematocrit), or RBF = RPF/(1 - Hct). In a normal individual, renal blood flow will be approximately double the renal plasma flow.
12. Prostaglandins cause dilation of the afferent arteriole and an increase in the GFR.
Answers
First Aid for the® USMLE Step 1 2011 EXPRESS workbook page 171
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
13. Angiotensin II causes constriction of the efferent arteriole and an increase in the GFR.
14. No change; increase; increase.
15. Decrease; decrease; no change.
16. Excretion rate = V × Ux; where V is the urine flow rate and Ux is the urine concentration of X.
17. Glucose is reabsorbed in the proximal tubule by sodium/glucose co-transport.
18. 350 mg/dL.
19. Amino acids are filtered and then reabsorbed from the urine at the level of the proximal tubule by three distinct sodium-dependent transporters, each with competitive inhibition.
20. Ammonia.
21. Sodium, potassium, and chloride.
22. Magnesium and calcium.
23. PTH.
24. Collecting tubule.
25. Insertion of aquaporin water channels on the luminal side of the collecting tubules, resulting in increased water reabsorption.
26. Reabsorption.
27. Increase. (Chloride is reabsorbed distally in the nephron.)
28. Vasoconstriction; stimulation of sodium resorption in the proximal tubule; release of aldosterone from the adrenal cortex; release of ADH from the posterior pituitary; and simulation of thirst via the hypothalamus.
29. Lungs.
30. Renin.
31. Osmolarity; blood volume; low; blood volume.
32. Aldosterone secretion from the adrenal cortex increases sodium channel and sodium/potassium pump insertion in principal cells and enhances potassium and hydrogen excretion by upregulating potassium channels in the principal cells and hydrogen ion channels in the intercalated cells. These actions create a favorable gradient for sodium and water reabsorption.
33. Decreases; increases.
34. Juxtaglomerular cells.
35. Erythropoietin.
36. 1α-Hydroxylase, which converts 25-OH vitamin D to 1,25(OH)2 vitamin D.
page 172 First Aid for the® USMLE Step 1 2011 EXPRESS workbook
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
37.
Effect Shifts K
+ Into Cell
Hypokalemia Shifts K
+ Out of Cell
Hyperkalemia
Acidosis √
Alkalosis √
β-Adrenergic agonists √
β-Adrenergic antagonists √
Cell lysis √
Digitalis √
Hyperosmolarity √
Hypo-osmolarity √
Insulin √
Insulin deficiency √
38. Digitalis blocks the Na+/K
+/APTase pump from pumping K
+ into the cell in exchange for Na
+, thus
leaving the K+ outside the cell.
39. Decreased serum bicarbonate.
40. Hyperventilation, which causes PCO2 to decrease.
41. Methanol (formic acid), Uremia, Diabetic ketoacidosis, Paraldehyde or Phenformin, Iron tables or Isoniazid, Lactic acidosis, Ethylene glycol (oxalic acid), and Salicylates. (Remember: MUDPILES.)
PATHOLOGY
42. Azotemia, oliguria, hypertension, and proteinuria <3.5 g/day.
43. A-3, B-4, C-5, D-2, E-1.
44. Acute poststreptococcal glomerulonephritis.
45. c-ANCA; p-ANCA.
46. Systemic lupus erythematosus.
47. Massive proteinuria (>3.5 g/day), edema, fatty casts, and hyperlipidemia.
48. A-1, B-4, C-3, D-5, E-6, F-2.
49. Focal segmental glomerular sclerosis.
50. Nonenzymatic glycosylation of the efferent arterioles, leading to an increased GFR and thus mesangial expansion.
51. Calcium in the form of calcium oxalate, calcium phosphate, or both.
52. Oxalate crystals.
First Aid for the® USMLE Step 1 2011 EXPRESS workbook page 173
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
53. Because of the patient’s leukemia (a disease with high cell turnover), he is at risk for developing uric acid stones due to hyperuricemia, which are radiolucent and do not appear on x-ray studies.
54. WAGR complex = Wilms' tumor, Aniridia, Genitourinary malformation, and mental-motor Retardation.
55. A-10, B-5, C-7, D-9, E-3, F-8, G-4, H-2, I-1, J-6.
56. Renal ischemia, crush injury, and toxins.
57. Prerenal (e.g., hypotension and reduced renal blood flow), intrinsic renal (e.g., tubular necrosis), and postrenal (outflow obstruction).
58. False; bilateral (not unilateral) postrenal outflow obstruction leads to acute renal failure.
59. Postrenal.
60. Prerenal.
61. Na+/H2O retention, hyperkalemia, metabolic acidosis, uremia, anemia, renal osteodystrophy,
dyslipidemia, and retarded grown and development in children.
62. An autosomal dominant mutation in the APKD1 or APKD2 gene.
63. Death usually results from complications of chronic kidney disease or hypertension (due to increased renin production).
64. Renal failure in utero, from autosomal recessive polycystic kidney disease, can lead to Potter’s syndrome (see page 132). After the neonatal period, potential complications include hypertension, portal hypertension, and progressive renal insufficiency.
PHARMACOLOGY
65. Acetazolamide acts as a carbonic anhydrase inhibitor, causing self-limited sodium bicarbonate diuresis and a reduction in total-body bicarbonate stores.
66. Furosemide inhibits the Na+/K
+/Cl
- cotransport system in the thick ascending limb of the loop of
Henle, thereby abolishing the hypertonicity of the medulla and preventing the concentration of urine.
67. Ethacrynic acid.
68. Glucose (hyperGlycemia), lipids (hyperLipidemia), uric acid (hyperUricemia), and calcium (hyperCalcemia). (Remember: HyperGLUC.)
69. Spironolactone competitively antagonizes the aldosterone receptor in the cortical collecting tubule.
70. ACE inhibitors prevent the inactivation of bradykinin, a potent vasodilator. Increased bradykinin levels can lead to angioedema in susceptible individuals.
71. To treat hypertension, to treat congestive heart failure, and to slow the progression of diabetic renal disease.
page 174 First Aid for the® USMLE Step 1 2011 EXPRESS workbook
Copyright © 2011 by MedIQ Learning, LLC All rights reserved
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Notes