Renal Physio MCQ

Question 1

1. In the presence of vasopressin, the greatest fraction of filtered water is absorbed in the:
   a. Proximal tubule
   b. Loop of Henle
   c. Distal tubule
   d. Cortical collecting duct
   e. Medullary collecting duct

Answer 1

a. Proximal tubule
greatest fraction of filtered water will always be absorbed from the PCT, irrespective of ADH action. In general, most reabsorption of substances (water, electrolytes, glucose, etc) takes place in the PCT.

Question 2

2. A freely filtered substance with plasma concentration of 2mg/mL, GFR of 100mL/min, urine concentration of 10mg/mL, urine flow rate of 5mL/min.
   a. Reabsorbed 150mg/min
   b. Reabsorbed 200mg/min
   c. Secreted 50mg/min
   d. Secreted 150mg/min
   e. Secreted 200mg/min

Answer 2

a. Reabsorbed 150mg/min
Amount that goes to glomerulus is 2x100 = 200mg/min
Amount that is excreted in urine is 10x5 = 50mg/min
Therefore the difference is the amount reabsorbed ie 200-50=150mg/min.

Question 3

3. Which of the following is not a potential cause of hypertonicity in the body?
   a. Water deprivation
   b. Massive sweating
   c. Massive secretion of vasopressin
   d. Diabetes insipidus
   e. Severe diarrhea

Answer 3

c. Massive secretion of vasopressin

Question 4

4. As a result of counter-current exchange, the fluid in the tubule is most hyperosmotic in the:
   a. Proximal convoluted tubule
   b. Distal convoluted tubule
   c. Ascending limb
   d. Descending limb
   e. Tops of the Loop of Henle

Answer 4

d. Descending limb

Question 5

5. What does dilation of the efferent arterioles do?
   a. Increase GFR
   b. Increase glomerular blood flow

Answer 5

b. Increase glomerular blood flow

Question 6

6. What happens to the GFR as the blood flows from afferent to efferent arterioles?
   a. Increase
   b. Decrease
   c. No change
   d. Increase, reaches a maximum, then decrease
   e. Decreases, reaches a minimum, then increase

Answer 6

b. Decrease
As more small molecules are filtered out, plasma oncotic pressure increases and capillary hydrostatic pressure decreases, thus net filtration decreases throughout from afferent to efferent arterioles.

Question 7

7. ADH secretion and release is caused by:
   a. Drinking 2L of distilled water
   b. Drinking 2L of hypertonic saline (sea water)
   c. Drinking 2L of isotonic saline
   d. Drinking 2L of isotonic glucose
   e. None of the above because increase in volume inhibits ADH secretion

Answer 7

b. Drinking 2L of hypertonic saline (sea water)

Question 8

8. Aldosterone:
   a. Increases reabsorption of potassium at the proximal convoluted tubules
   b. Secretion is stimulated by high blood potassium levels
   c. Increases secretion of renin
   d. Can lead to development of metabolic acidosis

Answer 8

b. Secretion is stimulated by high blood potassium levels

Question 9

9. A plasma pH of 7.32 may
   a. Lead to inhibition of respiration
   b. Cause Hb to have a lower affinity
   c. Arise due to lower CO2 content in the blood
   d. Lead to less renal excretion of H+ ions
   e. Arise due to pulmonary hypertension

Answer 9

b. Cause Hb to have a lower affinity

Question 10

10. ADH deficiency may lead to all of the following except:
    a. Increased urine output
    b. Increased thirst
    c. Increased urinary sodium excretion
    d. Urinary osmolality of <200mOsm/kg
    e. Increased plasma osmolality

Answer 10

c. Increased urinary sodium excretion

Question 11

11. ADH secretion is increased by all of the following factors except:
    a. Increase in plasma osmolality
    b. Loss of blood
    c. Pain
    d. Vomiting
    e. Alcohol

Answer 11

e. Alcohol
The two main triggers of ADH secretion are increased osmolality (A) and decreased volume (B & D). Pain (C) may also increase ADH secretion but the mechanism is unclear. Alcohol (E) inhibits ADH secretion (mechanism is also not well understood). Consequently, the kidneys produce more urine, leading to excessive urination and possible dehydration.

Question 12

12. Increased aldosterone secretion by an adrenal tumour may cause all of the following except:
    a. Hypertension
    b. Muscle weakness
    c. A low plasma potassium concentration
    d. Decreased urine volume
    e. Low plasma renin activity

Answer 12

d. Decreased urine volume
A: Aldosterone excess may result in increased blood pressure (RAAS mechanism).
B and C: Aldosterone increases potassium secretion, which when excessive can lead to hypokalemia (a low plasma potassium conc) and muscle weakness.
D: Increased aldosterone secretion will lead to increased reabsorption of sodium and water. This increased volume will trigger a compensatory reduction in ADH secretion, which will decrease water reabsorption at the collecting duct and thus increase or maintain (not decrease) urine volume.
Option E: Aldosterone decreases renin activity via negative feedback on the RAAS system.

Question 13

14. Respiratory compensation for metabolic alkalosis cannot be complete as
    a. Low PaCO2 stumulates respiration
    b. High PaCO2 stimulates respiration
    c. Low PaCO2 inhibits respiration
    d. High PaCO2 inhibits respiration
    e. None of the above, as respiratory compensation for metabolic alkalosis can be complete

Answer 13

b. High PaCO2 stimulates respiration

Question 14

15. Why does eating a very salty snack make you thirsty?
    a. ECF volume decreases
    b. ECK osmolarity decreases
    c. It would inhibit the hypothalamic chemoreceptors
    d. It would stimulate the hypothalamic osmoreceptors
    e. It would immediately cause a rise in urine output

Answer 14

d. It would stimulate the hypothalamic osmoreceptors

Question 15

16. Vasopressin
    a. Causes plasma to be osmolar
    b. Completely halts urine output
    c. Causes distal and collecting tubules to become impermeable to water
    d. Results in hyperosmolar urine output

Answer 15

d. Results in hyperosmolar urine output

Question 16

17. Inulin and substance X were found in the kidney. Ratio of inulin to X was 2:1 initially in the early tubule of the kidney but after which in later portions of the kidney the ratio became 1:1
    a. Substance X is secreted
    b. Inulin is reabsorbed
    c. X is reabsorbed
    d. Inulin is secreted

Answer 16

a. Substance X is secreted
Inulin is freely filtered, not secreted and not reabsorbed (that’s why it’s preferred for measuring GFR). Since the amount of Substance X was originally half that of inulin but later doubled (increased) to become equal, Substance X must have been secreted by the renal tubule (for its amount in the tubule to have increased).

Question 17

18. In a severely dehydrated patient, this is the best infusion to give:
    a. 0.9% sodium
    b. 5% glucose
    c. hypertonic solution
    d. isotonic saline

Answer 17

a. 0.9% sodium
d. isotonic saline
both are same

Question 18

19. Which of the following substances are not regulated by the kidneys?
    a. Glucose
    b. Sodium
    c. Hydrogen
    d. Phosphate
    e. Water

Answer 18

a. Glucose

Question 19

20. X has diarrhoea for 2 days. His pH is 7.3, CO2 is 40mmHg, bicarbonate concentration is 18mmol/L. what acid base disorder does he have?
    a. Metabolic acidosis
    b. Metabolic alkalosis
    c. Respiratory acidosis
    d. Respiratory alkalosis
    e. Both

Answer 19

a. Metabolic acidosis
pH is below normal, PaCO2 is normal, [HCO3-] is below normal. This indicates simple (uncompensated) metabolic acidosis. In this case, this is due to the loss of alkaline (bicarbonate-rich) intestinal fluid as a result of the diarrhoea.

Question 20

21. Oat cell carcinoma causes excessive production of ADH. What other condition mimics this condition?
    a. Moderate hemorrhage
    b. Excessive salt intake
    c. Excessive water intake
    d. Renal failure
    e. Evaporative dehydration

Answer 20

b. Excessive salt intake
d. Renal failure
e. Evaporative dehydration
A: severe haemorrhage is required before ADH is produced excessively. blood volume falls so greatly that “survival is threatened” and the body sacrifices osmolarity for increasing blood volume.
B: best answer out of the given options. consumption of excessive amounts of salt will cause the body to produce a lot more ADH.
D: Renal failure patients are unable to regulate serum osmolarity, ie unable to excrete excess sodium. This results in excessive ADH production.
E: Dehydration leads to increase ADH production

It is noteworthy that chronic kidney disease causes hyponatremia instead of hypernatremia

Question 21

22. Carbonic anhydrase inhibitor is expected to lead to
    a. Increased urinary acid excretion
    b. Increased bicarbonate reclamation
    c. Metabolic alkalosis
    d. Decreased bicarbonate regeneration

Answer 21

d. Decreased bicarbonate regeneration
Option D: Carbonic anhydrase is important for the regeneration of new bicarbonate (and hydrogen ion excretion) in the distal parts of the renal tubule. A carbonic anhydrase inhibitor will thus decrease bicarbonate regeneration and urinary acid excretion, leading to a metabolic acidosis.

Question 22

23. What causes a high serum anion gap?
    a. Metabolic alkalosis
    b. Vomiting
    c. Respiratory alkalosis
    d. Respiratory acidosis
    e. Metabolic acidosis

Answer 22

d. Respiratory acidosis

e. Metabolic acidosis

Question 23

24. If you took a drug that inhibited the reabsorption of Na+ in the PCT, you would
    a. Have an increased urine output
    b. Have a decreased urine output
    c. Have a decreased plasma [bilirubin] and become jaundiced
    d. Have decreased absorption of fats and have grey-white feces

Answer 23

a. Have an increased urine output

Question 24

25. Glucose is
    a. Filtered, reabsorbed, and secreted
    b. Filtered, and reabsorbed, but not secreted
    c. Filtered, and secreted, but not reabsorbed
    d. Filtered, and neither secreted nor reabsorbed

Answer 24

b. Filtered, and reabsorbed, but not secreted

Question 25

26. If mean arterial pressure (MAP) increased from 120mmHg to 154mmHg, GFR would most likely a. Increase b. Decrease c. Stay the same

Answer 25

c. Stay the same | autoregulation

Question 26

27. Typically, as GFR increases, the [Na+] of the filtrate reaching the DCT will a. Increase b. Decrease c. Stay the same

Answer 26

a. Increase As GFR increases, more Na+ is filtered across than can be reabsorbed; thus, the [Na+] of the filtrate reaching the DCT will increase.

Question 27

28. What would happen to the GFR if the hydrostatic pressure exerted by the fluid in the capsular space increased? a. GFR would increase b. GFR would decrease c. GFR would not change

Answer 27

b. GFR would decrease

Question 28

29. While the kidneys process about 180L of blood-derived fluids per day, the amount that actually leaves the body is: a. 50%, or 90L b. 100%, or 180L c. 10%, or 18L d. 1%, or 1.8L

Answer 28

d. 1%, or 1.8L

Question 29

30. The fluid in the capsular space is similar to plasma except that it does not contain a significant amount of: a. Glucose b. Sodium c. H+ d. Albumin

Answer 29

d. Albumin

Question 30

32. True or False: Glomerular filtration is an ATP-driven process

Answer 30

False: Filtration across the glomerular membrane is down a pressure gradient (from an area of high to low hydrostatic pressure) and is not an energy dependent process.

Question 31

33. Aldosterone causes: a. Decreased K+ in the urine b. Increased Na+ in the urine c. Increased urine output d. Decreased urine output

Answer 31

d. Decreased urine output

Question 32

34. Creatinine is a a. Chemical that is typically not secreted b. Substance typically found in greater amounts in renal arteries than in renal veins c. Building block for complex carbohydrates d. 2 of the above are correct

Answer 32

b. Substance typically found in greater amounts in renal arteries than in renal veins

Question 33

36. In humans, the thirst centre is located in the a. Adrenal cortex b. Pons c. Hypothalamus d. Medulla Oblongata e. Thalamus

Answer 33

c. Hypothalamus

Question 34

37. The longer the ______________, the greater an animal’s capacity to conserve water and to concentrate the solutes excreted in the urine.

Answer 34

Loop of Henle

Question 35

38. Hormonal control of urinary excretion primarily affects: a. Bowman’s capsules b. DCTs and collecting ducts c. PCTs and Loops of Henle d. Urinary bladder

Answer 35

Option B: The main hormones which control urine production are aldosterone and ADH, which act primarily on the DCT and collecting duct.

Question 36

39. As dehydration increases, the release of ADH from the posterior pituitary will a. Increase b. Decrease c. Stay the same

Answer 36

a. Increase

Question 37

40. The plasma protein concentration of a patient with untreated glomerulonephritis would be expected to be: a. Greater than normal b. Less than normal c. Normal

Answer 37

b. Less than normal In untreated glomerulonephritis, there is autoimmune damage to the filtration barrier of the glomerular membrane, resulting in (abnormally) large amounts of plasma proteins (eg albumin) being filtered across the membrane which cannot be reabsorbed and are lost in the urine. Thus, the plasma protein concentration of a patient with untreated glomerulonephritis would be expected to be lower the normal.

Question 38

41. Which of the following is NOT a function of atrial natriuretic peptide? a. It acts to decrease aldosterone release from the adrenal cortex b. It acts to increase urine output c. It acts to increase blood pressure d. It acts to decrease ADH release

Answer 38

c. It acts to increase blood pressure Atrial natriuretic peptide (ANP) opposes the effects of aldosterone and the RAAS system; thus it decreases aldosterone and ADH release (Options A and D), increases urine output (Option B) and decreases (not increases) blood pressure (Option C).

Question 39

42. The addition of a strong acid to the extracellular fluid would result in the increased formation of: a. NaHCO3- b. H2CO3 c. OH- d. All of the above

Answer 39

b. H2CO3 The main extracellular buffer is the bicarbonate buffer system, which can be represented by the following equilibrium: H+ + HCO3- ⬄ H2CO3 ⬄ CO2 + H2O. When strong acid (H+) is added to the extracellular fluid (ECF), the equilibrium will shift to the right to maintain the pH of the ECF, increasing the formation of H2CO3.

Question 40

43. Which of the following could cause excessive urine output? a. Hyperaldosteronism b. Hypersecretion of ADH c. Hyperventilation d. Severe hypoinsulinemia

Answer 40

d. Severe hypoinsulinemia eg. type 1 DM A: Increased sodium and water reabsorption due to increased activity of Na-K transporter, reducing urine output, HOWEVER, remember that it is unlikely that Hypernatremia occurs together with Conn’s due to aldosterone escape

Question 41

44. The term alkaline reserve is used to describe the ________________ buffer system a. Phosphate b. Hemoglobin c. Bicarbonate d. Protein

Answer 41

c. Bicarbonate

Question 42

45. If MAP increased from 120mmHg to 154 mmHg, GFR would most likely a. Increase b. Decrease c. Stay the same

Answer 42

c. Stay the same | autoregulation

Question 43

46. In an attempt to compensate for plasma acidosis a. Breathing rate and depth will increase b. Breathing rate and depth will decrease c. Breathing rate will increase and depth will decrease d. Breathing rate and depth will not change since only the renal mechanism can deal with acidosis

Answer 43

a. Breathing rate and depth will increase

Question 44

47. The pH of the blood varies directly with a. HCO3- b. H+ (Remember that pH is –ve log of concentration of Hydrogen ions) c. PCO2

Answer 44

b. H+

Question 45

49. The micturition centre is located in the a. Pons b. Medulla c. Cerebellum d. Basal ganglia

Answer 45

a. Pons

Question 46

50. The vasa recta creates the osmotic gradient in the kidney’s medulla a. This statement is true b. This statement is false because the PCT creates the gradient c. This statement is false because the DCT creates the gradient d. This statement is false because the loop of Henle creates the gradient

Answer 46

d. This statement is false because the loop of Henle creates the gradient

Question 47

52. the main solute component of urine is

Answer 47

urea.

Question 48

55. Which of the following would not be secreted from the ISF into the filtrate a. Organic acids b. Amino acids c. Organic bases d. Creatinine

Answer 48

b. Amino acids

Question 49

57. Which of the following is incorrect concerning ADH? a. Its production is regulated by plasma osmolarity b. Its activity is affected by alcohol c. It acts on the collecting duct and decreases its permeability to water d. It is stored in the posterior pituitary

Answer 49

c. It acts on the collecting duct and decreases its permeability to water A: osmoreceptors located in the hypothalamus will sense the change in osmolarity and increase secretion of ADH when blood becomes hyperosmolar. However, changes in blood pressure beyond limits will prompt the hypothalamus to produce more ADH regardless of blood osmolarity B: alcohol reduces secretion of ADH

Question 50

58. Which of the following is not a unit of the nephron? a. Bowman’s capsule b. PCT c. DCT d. Medullary papilla

Answer 50

d. Medullary papilla

Question 51

60. Which of the following is a function of the kidneys? a. Maintenance of plasma pH b. Maintenance of plasma [electrolyte] c. Gluconeogenesis d. All of the above e. 2 of the above

Answer 51

d. All of the above

Question 52

63. Which of the following is not a stage in urine formation? a. Glomerular filtration b. Glomerular secretion c. Tubular reabsorption d. Tubular secretion

Answer 52

b. Glomerular secretion

Question 53

64. Which of the following is not a means of regulating GFR? a. Regulation via skeletal muscle b. Regulation via smooth muscle c. Hormonal regulation d. Neuronal regulation

Answer 53

a. Regulation via skeletal muscle (All skeletal muscle is under voluntary control, regulation of GFR is an an autonomic process, furthermore, there is only smooth muscle located in the walls of the afferent and efferent arterioles)

Question 54

65. Increased sympathetic stimulation of afferent arterioles results in: a. Increased filtrate volume per unit time b. Decreased filtrate volume per unit time c. Increase GFR d. Decreased ANP release by macula densa cells

Answer 54

b. Decreased filtrate volume per unit time (Sympathetic stimulation would cause vasoconstriction in the afferent arterioles, reducing the amount of blood reaching the glomerulus, thus GFR would decrease)

Question 55

66. Renin is produced by the a. Mesangial cells b. Macula densa c. Principal cells of the DCT d. Juxtaglomerular cells

Answer 55

d. Juxtaglomerular cells

Question 56

67. The function of the macula densa cells is to: a. Prevent water reabsorption in the ascending limnb of the loop of Henle b. Add bicarbonate ions to the filtrate c. Secrete renin d. Monitor filtrate [NaCl] e. Secrete glucose

Answer 56

d. Monitor filtrate [NaCl]

Question 57

68. One function of ANP is to a. Increase afferent arteriole pressure b. Increase renal blood flow c. Enhance the effects of ADH d. Inhibit the effects of aldosterone e. Increase blood volume

Answer 57

d. Inhibit the effects of aldosterone (ANP acts to reduce blood pressure by reducing blood volume; as it name implies, it does this by inhibiting the effects of aldosterone)

Question 58

70. If the diameter of the afferent arteriole < the diameter of the efferent arteriole, then which of the following will result? a. Decrease NFP b. Decreased glomerular BP c. Increased GFR d. Increased [Na+] in the filtrate reaching the DCT e. 2 of the above f. None of the above

Answer 58

e. 2 of the above Net filtration pressure will decrease as they would be less blood entering via the afferent arteriole and less hydrostatic pressure due to the larger diameter of the efferent arteriole GBP decreases due to the decreased renal blood flow

Question 59

71. The most important function of the JG apparatus is to: a. Secrete water into the filtrate b. Reabsorb Na+ c. Generate bicarbonate ions to compensate for renal acidosis d. Secrete renin e. Secrete aldosterone

Answer 59

d. Secrete renin

Question 60

73. In a patient who is dehydrated from vomiting and diarrhea, which is likely to be found in higher amounts in the plasma? a. ADH b. Aldosterone c. ANP d. a and b e. a and c

Answer 60

d. a and b ADH: Hyperosmotic plasma stim secretion of ADH to increase reabs of water from collecting ducts Increased sympathetic stimulation from low bp + Low sodium ion concentration at the DCT would stimulate JG cells to produced renin… RAAS → Increased aldosterone ANP is secreted by right atrium when blood volume is low; right side of circulation is a low pressure system thus, it measures blood pressure as blood volume

Question 61

75. Damage to which of the following could result in the most drastic proteinuria? a. PCT b. DCT c. Collecting duct d. Peritubular capillaries e. Glomerular capillaries

Answer 61

e. Glomerular capillaries Where ultrafiltration occurs, if damaged, there would be no filtration barrier and large molecules such as proteins would be able to pass through into the kidney tubules

Question 62

76. If lactic acid is injected IV, then plasma bicarbonate ion levels will immediately a. Increase b. Decrease c. Stay the same

Answer 62

b. Decrease (Natural buffers in the body will act to maintain body pH at 7.4 thus, concentration of bicarbonate ions would be reduced)

Question 63

77. During a sympathetic response, renin secretion will _____________. a. Increase b. Decrease c. Stay the same

Answer 63

a. Increase

Question 64

79. As renal afferent arteriole diameter increases, GFR a. Increase b. Decreases c. Stay the same

Answer 64

a. Increase | Increase afferent arteriole diameter would result in increased renal blood flow which would lead to an increase in GFR

Question 65

80. As plasma oncotic pressure increases, GFR a. Increases b. Decreases c. Stays the same

Answer 65

b. Decreases (GFR depends on the net hydrostatic pressure at the glomerulus, plasma oncotic pressure acts inwards towards the blood capillaries thus, reducing net hydrostatic pressure and GFR)

Question 66

81. When compared to the water permeability of the descending limb of the loop of Henle, the water permeability of the ascending limb is a. Increase b. Decreased c. Stays the same

Answer 66

b. Decreased | Ascending limb is impermeable to water so that the tubular fluid would be hypoosmolar

Question 67

82. As plasma osmotic (also known as colloid oncotic pressure) decreases below normal, plasma ADH levels a. Decrease b. Increase c. Stay the same

Answer 67

a. Decrease (Total blood pressure increases due to reduced colloid oncotic pressure, less stimulus for the release of ADH , this is sensed by the low pressure baroreceptors located on the right side of the heart)

Question 68

83. As plasma osmotic pressure increases above normal, renal collecting duct water permeability a. Decrease b. Increase c. Stay the same

Answer 68

b. Increase

Question 69

85. A woman was found comatose after an overdose of sleeping pills. Arterial pH – 7.02 HCO3- – 12 mEq/L PCO2 – 68 mmHg Which of the following describes her acid-base status? a. Uncompensated respiratory acidosis b. Uncompensated metabolic acidosis c. Simultaneous respiratory and metabolic acidosis d. Respiratory acidosis with incomplete renal compensation e. Respiratory acidosis with complete renal compensation

Answer 69

c. Simultaneous respiratory and metabolic acidosis (Since PCO2 is above the normal range of 35-45 mmHg, there is respiratory acidosis. Since bicarbonate is below the normal range of 22-26 mEq/L, there is metabolic acidosis) d: For this to be true, arterial pH would be slightly lower than normal (incomplete compensation) and bicarbonate would be above the normal range (metabolic compensation). e: for this to be true, arterial pH would be normal (complete compensation) and bicarbonate would be above the normal range (metabolic compensation).

Question 70

86. The following would be observed in a patient in hypovolemic shock except: a. Sweating b. decreased urine output c. higher central venous pressure d. increased plasma aldosterone concentration e. increased total peripheral resistance

Answer 70

a: due to increased sympathetic stimulus caused by the low bp b: when blood volume falls more than 20% the fall in pressure would act as a stronger stimulus for ADH compared to an increase in blood plasma osmolality. c: Unlikely, patient has lower blood volume than normal and is not suffering from heart failure, thus there would be no accumulation of blood on the right side of the heart) d. 1: Increased sympathetic stimulus causing a release of renin from the JG cells…RAAs, 2: Low Na concentration measured at the DCT thus, Macula densa cells act via paracrine effects to stimulate secretion of renin e. increased sympathetic stimulus causing vasoconstriction and increasing the venous return into the right side of the heart, reduced radius of veins increases the resistance to blood flow)

Question 71

``` 87. Aliskiren is a drug which inhibits the enzyme renin. Which of the following effects would you observe in a patient taking this drug? A. Lower blood pressure B. Decreased heart rate C. Increased cardiac contractility D. Increased fluid retention E. Increased total peripheral resistance ```

Answer 71

A. Lower blood pressure (Likely, RAAS not able to be activated thus, aldosterone secretion is reduced and less water is reabsorbed with sodium at the DCT leading to lower blood volume and blood pressure) B, E: unlikely, renin does not affect heart rate directly C: Unlikely, renin does not affect cardiac contractility directly D: should be reduced fluid retention causes less renin means less aldosterone which would cause less water to be reabsorbed along with sodium

Question 72

88. What does dilatation of the efferent arterioles do? a. Increase GFR b. Increase glomerular blood flow c. Decrease glomerular blood flow d. Decrease renal plasma flow

Answer 72

b. Increase glomerular blood flow

Question 73

89. A 60 year old man with lung cancer. Low plasma osmolality, Low sodium concentration, High urine osmolality. a. His aldosterone levels are high b. Reduced salt intake c. He has an ADH secreting tumour d. His ADH receptors are not responding

Answer 73

c. He has an ADH secreting tumour (TIP: Pathology in sodium concentration is more likely due to ADH rather than aldosterone most of the time. In this case, the low plasma osmolality and high urine osmolality points towards too much water being reabsorbed thus, ADH is the problem)

Question 74

90. Infusion of isotonic dextrose will a. Reduce ECF osmolality immediately after infusion b. Increase ADH release immediately after infusion c. Increase BP more effectively than an equal volume of isotonic saline d. Expand the intracellular compartment to a greater extent than the ECF after a few hours e. Increase reabsorption of interstitial fluid from the venous end of capillaries

Answer 74

d. Expand the intracellular compartment to a greater extent than the ECF after a few hours (Dextrose would be metabolised by the cells, causing the plasma osmolality to become hypoosmotic, osmosis occurs with water flowing from the ECF to ICF)

Question 75

91. Which of the following is correct with respect to Na handling at the nephron a. Na reabsorption at collecting duct is passive b. H2O reabsorption with Na at all segments c. Net Na excretion regulated by aldosterone d. Na K ATPase on apical membrane e. decreased Na excretion in urine when BP increased

Answer 75

c. Net Na excretion regulated by aldosterone a. Na reabsorption at collecting duct requires active transport via Na-k transporters b. H2O reabsorption - passive reabsorption via osmosis at the collecting duct when ADH is present d. Na K ATPase on basolateral, NOT apical membrane e. Less aldosterone is secreted when BP is high, means there is less reabsorption of Na and MORE Na excreted

Question 76

Decrease in urine output may result from the following except a. Bilateral renal vein thrombosis b. Strong sympathetic stimulation c. low vasa recta flow d. Treat severe edema with albumin infusion e. constriction of efferent arterioles

Answer 76

e. constriction of efferent arterioles (Results in an increase in net hydrostatic pressure at the glomerulus, increasing GFR) a: Reduced renal blood flow to the kidneys would reduce GFR leading to less filtrate in tubules b: increased aldosterone secretion due to stimulus of renin secretion, more Na and water reabs at the DCT c: flow of the vasa recta normally v slow to allow maintenance of countercurrent exchange mechanism and prevent washout of both metabolites and solutes (wld otherwise decrease osmolality of interstitium and decrease reabs from the tubules) d: reduced net hydrostatic pressure at the glomerulus thus, reduced GFR and less filtrate enters the tubules

Question 77

93. What function do the sympathetic nerves to the kidneys have? / Which of these is sympathetic stimulation essential to? a. Na+ - K+ ATPase b. Renal autoregulation of bloodflow c. Urine osmolality d. RAAS e. None of the above

Answer 77

e. None of the above | Keyword ESSENTIAL, without sympathetic stimulation the processes can still carry on

Question 78

94. Which of the following increases urine inulin or creatine excretion: a. constriction of afferent arteriole b. constriction of efferent arteriole c. dilation of afferent arteriole d. dilation of efferent arteriole e. both dilation of afferent arteriole and constriction of efferent arteriole

Answer 78

e. both dilation of afferent arteriole and constriction of efferent arteriole

Question 79

Increase of serum creatinine from 85-130umol/L. Select least likely reason a. Decreased renal perfusion b. normal variation c. vasodilation of efferent arteriole due to drugs d. Increased muscle mass from body building e. decreased creatinine secretion

Answer 79

b. normal variation

Question 80

96. Renal acid excretion is increased in: a. respiratory alkalosis b. adding carbonic anhydrase c. less glutamine synthesis at renal tubule d. renal tubule acidosis e. increased hco3- in blood

Answer 80

b. adding carbonic anhydrase

Question 81

97. The kidneys play an important role in regulating body pH by excreting all of the following except: a. Sulfate anions b. hydrogen ions c. Phosphate ions d. Bicarbonate ions e. chloride ions

Answer 81

e. chloride ions

Question 82

98. Renin secretion is caused by an increase in: a. Arterial blood pressure b. Sympathetic activity c. NaCl delivery to macula densa d. Plasma osmolarity e. Arterial blood volume

Answer 82

b. B. Sympathetic activity

Question 83

99. After a person decides to pass urine, which of the following events DOES NOT occur? a. voluntary relaxation of the pelvic floor muscles via the pudendal nerve b. cessation of signals from the brain that inhibit the sacral parasympathetic neurons c. increase in hypogastric sympathetic nerve activity d. contraction of the detrusor muscle e. relaxation of the smooth muscle sphincters at the bladder outlet

Answer 83

c. increase in hypogastric sympathetic nerve activity

Question 84

100. High plasma glucose in diabetics can directly or indirectly cause the following except a. glycosuria b. high urine sodium excretion c. high urine volume per day d. fall in plasma osmolality e. increase thirst

Answer 84

d. fall in plasma osmolality (Osmotic diuresis caused by glucose would increase plasma osmolality) a: when filtered load of glucose exceeds the transport maximum of the SGLT b: glucose acting as an osmotically active agent to reduce the reabsorption of sodium c: glucose acting as a diuretic and reducing the reabsorption of water and sodium e: thirst receptors stimulated by the high plasma osmolality

Question 85

101. large increase in water excreted all in a day is a result of all except a. diabetes mellitus b. excess drinking of water c. deficiency of ADH d. renal resistance to ADH e. deficiency of aldosterone

Answer 85

e. deficiency of aldosterone (Aldosterone is more for maintaining blood pressure not so much of controlling plasma osmolality, thus it does not significantly affect urine output) b: psychological polydipsia note renal resistance to ADH is similar to deficiency in ADH

Question 86

102. Excessive production of aldosterone from an adrenal tumor results in the following except a. high bp b. low serum potassium c. high plasma renin activity d. high plasma aldosterone levels e. muscle weakness

Answer 86

c. high plasma renin activity unlikely, there would be negative feedback due to the high bp (more NaCl reach macula densa, reduces renin secretion by JG cells) a. aldosterone wld increase activity of Na-k ATPase causing increased reabs of sodium and water at DCT. lead to increased fluid retention and greater systemic filling pressure thus, causing blood pressure to increase d. adrenal secreting tumours are not affected by the negative feedback mechanism e. low serum potassium would lead to muscle weakness, there would be a more negative resting membrane potential in the cells which would mean greater Na ions are required to fire off an action potential

Question 87

103. After a high salt intake, which of the following will occur? a. Osmoreceptor cells will swell b. Interstitial fluid osmolality increases c. Na reabsorption in the PCT is reduced d. Intracellular osmolality decreases e. Intravascular volume decreases

Answer 87

b. Interstitial fluid osmolality increases (Interstitial fluid is a component of ECF so since plasma osmolality is high interstitial fluid osmolality should be high as well) a. Osmoreceptor cells will swell (Unlikely, cells swell when water enters via osmosis since plasma is hyperosmolar water would move outwards instead of inwards) d: Intracellular osmolality Increase as water flows outwards)

Question 88

104. Which of the following is associated with increased osmolality in the inner medullary interstitium of the kidney? a. Increased blood flow through vasa recta b. Administration of a loop diuretic that inhibits the Na reabsorption in TAL c. Hypoxic conditions of the kidney d. Longer loop of Henle and vasa recta e. Decreased urea permeability of the inner medullary collecting duct

Answer 88

d. Longer loop of Henle and vasa recta (Concentration of the fluid in the kidney tubules can become even higher when the loop increases in length due to countercurrent exchange) a: increased blood flow through the vasa recta would cause to wash out of the medullary interstitium due to the increased reabsorption of sodium, causing the osmolality to decrease b: Medullary insterstitium would become hypoosmolar as a result due to less sodium being reabsorbed from the kidney tubules into the medulla

Question 89

105. Sodium reabsorption in the proximal tubule is a. Regulated by aldosterone b. By secondary transport c. By renal perfusion d. Increases when plasma Na+ concentration in the peritubular capillaries is high

Answer 89

a. Regulated by aldosterone (Only regulated by aldosterone at the DCT)

Question 90

106. Carbonic anhydrase inhibitors may a. Increase bicarbonate reclamation by the proximal tubule b. Decrease H2O reabsorption by the proximal tubule c. Increase alkaline tide d. Increase CO2 carrying capacity of red blood cells e. Treat metabolic alkalosis

Answer 90

e. Treat metabolic alkalosis (Though not conventionally used in the clinical setting, carbonic anhydrase inhibitors can be used to treat metabolic alkalosis. Its primary mechanism of action is in inhibiting the enzyme, carbonic anhydrase, which results in reduced reabsorption of sodium bicarbonate and increased excretion, culminating in lower bicarbonate levels)

Question 91

107. In the acute treatment of hyperkalemia, a. Urinary excretion of potassium is an effective immediate treatment b. Calcium injections increase the duration of the plateau phase of cardiac action potential c. An injection of insulin and glucose acts rapidly d. Removal of potassium via the gut occurs via the ileum e. Furosemide inhibits potassium reabsorption in the distal tubule

Answer 91

c. An injection of insulin and glucose acts rapidly (Insulin would increase the activity of the Na-K ATPase which would increase the excretion of potassium from the kidneys)

Question 92

108. With regards to H+ secretion in the nephron a. Carbonic anhydrase inhibitor increases H2CO3 dissociation b. Hypercapnia increases production of H2CO3 c. Metabolic acidosis decrease in glutamine synthesis d. Aldosterone decreases H+ secretion

Answer 92

(i think) b. Hypercapnia increases production of H2CO3 (Equilibrium shift due to high concentration of CO2) d: Aldosterone would stimulate the alpha-intercalated cells to increase the secretion of hydrogen ions)

Question 93

109. An elevated serum anion gap is likely in which situation? a. Metabolic alkalosis b. Hyperventilation c. Administration of ammonium chloride d. After prolonged repeated vomiting e. Severe insulin deficiency

Answer 93

e. Severe insulin deficiency

Question 94

110. A well-conditioned mountain climber climbs midway of Mt Everest. His arterial blood values are PaCO2 of 30mmhg, pH 7.45, serum HCO3- of 20mmol/L. What does he have? a. Metabolic acidosis b. Mixed respiratory alkalosis and metabolic acidosis c. He has lactic acidosis from climbing activity and tissue hypoxia leading to metabolic acidosis d. Metabolic alkalosis with acute respiratory compensation e. Chronic respiratory alkalosis with metabolic compensation

Answer 94

e. Chronic respiratory alkalosis with metabolic compensation

Question 95

111. A man runs 20km in the hot sun without drinking water. a. Plasma osmolarity of 270mOsm b. decreased ADH c. increased intracellular volume d. decreased peritubular oncotic pressure e. Anion gap is increased

Answer 95

e. Anion gap is increased | Lactic acidosis