Pharmacology - Problem Drill 10: Diuretics

Question No. 1 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 1. The ______is the functional unit of the kidney where blood is filtered and concentrated to form urine.

(A) Glomerulus Question #01 (B) GFR (C) Nephron (D) Cortex (E) Medulla

Incorrect! The glomerulus is a specialized capillary bed at the beginning of each nephron.

B. Incorrect! GFR is the glomerular filtration rate.

C. Correct! Feedback on Then nephron is the functional unit of the kidney where blood is filtered Each Answer and concentrated to form urine. Choice

D. Incorrect! The cortex is not considered to be the functional unit of the kidney.

E. Incorrect! The medulla is not considered to be the functional unit of the kidney.

The nephron is the functional unit of the kidney. Each kidney contains approximately 1 million nephrons that are virtually identical. The nephron is divided into the proximal tubule, the loop of Henle, the distal tubule, and the collecting duct. The glomerular portion of all nephrons is located in the cortex, but while the tubules of some nephrons are found Solution only in the cortex, the tubules of other nephrons (those located deep within the cortex) extend into the medulla.

The correct answer is (C).

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 2 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 2. ______receives 90% of the incoming kidney blood flow via the renal artery.

(A) Bowman’s capsule Question (B) Cortex #02 (C) Medulla (D) Papilla (E) Proximal distal tubule

A. Incorrect! Bowman's capsule is a specialized capillary bed located inside a layer of epithelial cells in the kidney.

B. Correct! The cortex is the part of the kidney which receives 90% of the incoming kidney blood flow via the renal artery.

Feedback on Each C. Incorrect! Answer Think of another section of the kidney. Choice

D. Incorrect! Think of another section of the kidney.

E. Incorrect! The proximal distal tubule is a section of the nephron.

Each kidney as an identical structure that can be divided into three sections: the outer cortex, the central medulla, and the inner papilla. The cortex receives approximately 90% of the incoming blood flow from the renal artery. Once it enters the kidney, the renal artery branches into smaller arterioles that supply smaller structures called glomeruli. Blood then leaves the kidney by the renal vein. Solution

The correct answer is (B).

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 3 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 3. The ______restricts the passage of molecules based on charge, by allowing neutral or cationic molecules to freely pass, while anionic molecules are restricted.

Question #03 (A) Bowman’s capsule (B) Glomerulus (C) Proximal tubule (D) loop of Henle (E) Distal tubule

A. Incorrect! Bowman's capsule is a specialized capillary bed located inside a layer of epithelial cells in the kidney.

B. Correct! The glomerulus restricts the passage of molecules based on charge, by allowing neutral or cationic molecules to freely pass, while anionic molecules are restricted.

Feedback on Each Answer C. Incorrect! Choice The proximal tubule is located after this barrier.

D. Incorrect! The loop of Henle is located after this barrier.

E. Incorrect! The distal tubule is located after this barrier.

The glomerulus restricts the passage of molecules into the nephron by preventing large molecules from passing through the capillary wall. The glomerular wall also restricts the passage of molecules based on charge, by allowing neutral or cationic molecules to freely pass, while anionic molecules are restricted.

The correct answer is (B).

Solution

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 4 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 4. Loop diuretics are useful for treating patients with salt and water overload due to:

(A) Acute pulmonary edema Question #04 (B) Chronic heart failure (C) Nephritic syndrome (D) Renal failure (E) All of the above

A. Incorrect! Loop diuretics are useful for treating patients with salt and water overload due to acute pulmonary edema, but this is not their only use.

B. Incorrect! Loop diuretics are useful for treating patients with salt and water overload due to chronic heart failure, but this is not their only use.

C. Incorrect! Loop diuretics are useful for treating patients with salt and water overload Feedback on due to nephritic syndrome, but this is not their only use. Each Answer

Choice

D. Incorrect! Loop diuretics are useful for treating patients with salt and water overload due to renal failure, but this is not their only use.

E. Correct! Loop diuretics are useful for treating patients with salt and water overload due to acute pulmonary edema, chronic heart failure, nephritic syndrome and renal failure.

Loop diuretics are useful in patients with salt and water overload due to: •Acute pulmonary edema •Chronic heart failure •Hepatic cirrhosis complicated by ascites •Nephrotic syndrome •Renal failure They are also used in patients with hypertension and the acute treatment Solution of hypercalcemia.

The correct answer is (E).

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 5 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 5. Furosemide is an example of a(n):

(A) Thiazide diuretic (B) Loop diuretic Question #05 (C) Indirect acting diuretic (D) Osmotic diuretic (E) Potassium-sparing diuretic

A. Incorrect! Furosemide acts at the Loop of Henle.

B. Correct! Furosemide is an example of a loop diuretic.

C. Incorrect! Furosemide is a direct-acting diuretic. Feedback on

Each Answer

Choice

D. Incorrect! R Furosemide acts at the Loop of Henle.

E. Incorrect! Furosemide acts at the Loop of Henle.

Loop diuretics inhibit the Na+/K+/Cl- pump in the thick ascending loop and thereby cause more of the filtered sodium to be excreted. Loop diuretics are perhaps the most powerful diuretics since they can cause 15-25% of filtered sodium to be excreted. Additionally, they cause K and Ca loss resulting in hypokalemia, metabolic alkalosis and hypovolemia. Examples include furosemide, bumetanide, torasemide and pirentanide.

Solution The correct answer is (B).

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 6 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 6. Mannitol is an example of a(n):

(A) Thiazide diuretic (B) Loop diuretic Question #06 (C) Direct acting diuretic (D) Osmotic diuretic (E) Potassium-sparing diuretic

A. Incorrect! Mannitol is not a thiazide drug.

B. Incorrect! Mannitol acts at the proximal tubule and descending limb, not the Loop of Henle.

C. Incorrect! Feedback on Mannitol is an indirect, not direct, acting diuretic. Each Answer Choice

D. Correct! Mannitol is an example of an osmotic diuretic.

E. Incorrect! Mannitol is not a potassium-sparing drug.

Osmotic diuretics are pharmacologically inert substances that are filtered in the glomerulus but are incompletely reabsorbed or not reabsorbed at all by the nephron. Their main effects are seen in the proximal tubule and the descending limb that are freely permeable to water. The presence of the non-reabsorbable solute reduces passive water reabsorption. An example of an osmotic diuretic is mannitol.

Solution The correct answer is (D).

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 7 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 7. Thiazide diuretics inhibit the ______in the distal convoluted tubule.

(A) Glomerulus Question #07 (B) Nephron (C) Proximal tubule (D) Carbonic anhydrase (E) Na+/Cl- co-transporter

A. Incorrect! The Glomerulus is not a part of the distal convoluted tubule.

B. Incorrect! The distal convoluted tubule is part of the nephron.

C. Incorrect! Feedback on The proximal tubule is part of the nephron. Each Answer Choice

D. Incorrect! Thiazide diuretics inhibit a different protein.

E. Correct! Thiazide diuretics inhibit the Na+/Cl- co-transporter in the distal convoluted tubule.

Thiazide diurectics mediate their effects by inhibiting the Na/Cl co- transporter in the distal convoluted tubule. They increase the loss of potassium and magnesium, but excretion of uric acid and calcium is decreased. Potassium loss is significant and can be serious. Examples include hydrochlorthiazide and bendrofluazide. Solution The correct answer is (E).

RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 8 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 8. Carbonic anhydrase inhibitors:

(A) Increase urine volume. (B) Decrease urine volume Question #08 (C) Increase GFR (D) Decrease GFR (E) Increase cellular bicarbonate

A. Correct! Carbonic anhydrase inhibitors increase urine volume.

B. Incorrect! Carbonic anhydrase inhibitors have the opposite effect.

C. Incorrect! Carbonic anhydrase inhibitors do not affect GFR. Feedback on Each Answer Choice D. Incorrect! Carbonic anhydrase inhibitors do no taffect GRF.

E. Incorrect! Carbonic anhydrase inhibitors deplete cellular bicarbonate.

Carbonic anhydrase found in the proximal convoluted tubule catalyzes the formation of carbonic acid from CO2 and water. The acid dissociates to form hydrogen and bicarbonate ions, the bicarbonate ions pass into the plasma and the hydrogen ions are secreted into the lumen. Here the hydrogen ions combine with the filtered bicarbonate ions to form carbonic acid, which dissociates to form water and carbon dioxide, a reaction catalysed by carbonic anhydrase. The carbon dioxide diffuses back into the cell. Drugs which inhibit carbonic anhydrase therefore increase the volume of urine and result in the depletion of cellular bicarbonate. Solution

The correct answer is (A).

Question No. 9 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 9. Spironolactone is an example of ______, which are weak diuretics that act in the collecting tubules.

(A) Thiazide diuretic Question #09 (B) Loop diuretic (C) Indirect acting diuretic (D) Osmotic diuretic (E) Potassium-sparing diuretic

A. Incorrect! Spironolactone is not a thiazide diuretic.

B. Incorrect! Spironolactone is not a loop diuretic.

C. Incorrect! Spironolactone is a direct, not indirect, acting diuretic. Feedback on

Each Answer

Choice

D. Incorrect! Spironolactone is not an osmotic diuretic.

E. Correct! Spironolactone is an example of potassium-sparing diuretics, which are weak diuretics that act in the collecting tubules.

Potassium sparing diuretics are weak diuretics that act in the collecting tubules. Spironolactone exerts its effects by blocking the aldosterone receptor, while amiloride and triamterene and block the Na+ channels controlled by aldosterone’s protein mediator. They inhibit sodium reabsorption and decrease potassium excretion. By preventing Na+ entry, they also reduce the Na+/H+ exchange and thus inhibit H excretion resulting in alkalinization of urine. Both these agents promote the Solution excretion of uric acid.

The correct answer is (E).

Question No. 10 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 10. ______have a similar mechanism of action as compared to loop diuretics, but display significant toxicity.

(A) Carbonic anhydrase inhibitors Question #10 (B) Osmotic diuretics (C) Thiazide diuretics (D) Methylxanthines (E) Organic mercurial compounds

A. Incorrect! Carbonic anhydrase inhibitors have a very different mechanism of action compared to loop diuretics.

B. Incorrect! Osmotic diuretics have a very different mechanism of action compared to loop diuretics.

C. Incorrect! Thiazide diuretics have a very different mechanism of action compared to Feedback on loop diuretics. Each Answer Choice

D. Incorrect! Methylxanthines act by increasing glomerular filtration rate, not through action at the Loop of Henle.

E. Correct! Organic mercurial compounds have a similar mechanism of action as compared to loop diuretics, but display significant toxicity.

Organic mercurial compounds are known to have diuretic activity. These act in a similar way to loop diuretics to inhibit salt transport in the thick ascending loop. However these compounds are no longer used due to their significant toxicity.

Solution The correct answer is (E).