Question 1

Which of the following best describes the mechanism of action of loop diuretics in the nephron?

Accepted Answer

Inhibition of the Na+/K+/2Cl- cotransporter in the thick ascending limb of the loop of Henle

Question 2

A patient is prescribed acetazolamide for acute mountain sickness. Which of the following side effects is most likely to occur due to its mechanism of action?

Accepted Answer

Metabolic acidosis

Question 3

Which equation correctly represents the action of carbonic anhydrase in the proximal tubule?

Accepted Answer

$$\mathrm{CO_2$ + H_2O \xrightarrow{CA} H_2CO_3}$$

Question 4

Which of the following is a direct effect of blocking the Na+/K+ ATPase in renal tubular cells?

Accepted Answer

Decreased Na+ reabsorption from the tubular lumen

Question 5

A patient taking furosemide develops muscle weakness and cardiac arrhythmias. Which electrolyte abnormality is most likely responsible?

Accepted Answer

Hypokalemia

Question 6

Which of the following best explains why thiazide diuretics can cause hypercalcemia?

Accepted Answer

They increase Ca2+ reabsorption in the distal convoluted tubule via the Na+/Ca2+ antiporter.

Question 7

Which of the following is a major indication for the use of loop diuretics?

Accepted Answer

Pulmonary edema

Question 8

Which of the following drugs acts as a potassium-sparing diuretic by blocking epithelial sodium channels (ENaC) in the collecting duct?

Accepted Answer

Amiloride

Question 9

A patient with cirrhosis and ascites is started on spironolactone. What is the primary mechanism by which this drug exerts its diuretic effect?

Accepted Answer

Inhibition of aldosterone receptors in the collecting duct

Question 10

Which of the following best describes the difference between a symporter and an antiporter?

Accepted Answer

A symporter moves two ions in the same direction, while an antiporter moves them in opposite directions.

Question 11

Which of the following is a likely side effect of acetazolamide due to increased bicarbonate excretion?

Accepted Answer

Renal stones

Question 12

Which of the following equations represents the spontaneous dissociation of carbonic acid in the nephron?

Accepted Answer

$$\mathrm{H_2CO_3 \rightarrow $$HCO_3$$^- + H^+}$$

Question 13

Which of the following is a compensatory mechanism that can blunt the effect of a diuretic acting in the loop of Henle?

Accepted Answer

Increased Na+ reabsorption in the distal convoluted tubule

Question 14

Which of the following best explains why loop diuretics can cause metabolic alkalosis?

Accepted Answer

Increased Na+ delivery to the distal nephron stimulates H+ secretion in exchange for Na+ reabsorption.

Question 15

Which of the following is a major side effect of thiazide diuretics but not loop diuretics?

Accepted Answer

Hypercalcemia

Question 16

A patient is given mannitol for increased intracranial pressure. What is the primary mechanism by which mannitol acts as a diuretic?

Accepted Answer

It increases osmotic pressure in the renal tubule, preventing water reabsorption.

Question 17

Which of the following is the main reason why potassium-sparing diuretics are often combined with loop or thiazide diuretics?

Accepted Answer

To prevent hypokalemia

Question 18

Which of the following best describes the effect of antidiuretic hormone (ADH) on the collecting duct?

Accepted Answer

It increases the expression of aquaporin channels, enhancing water reabsorption.

Question 19

Which of the following is a likely effect of blocking aldosterone receptors in the collecting duct?

Accepted Answer

Decreased Na+ reabsorption and increased K+ retention

Diuretics: Mechanisms, Sites of Action, and Clinical Implications

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