127 Questions
What is the primary function of diuretics?
To eliminate excess water from the body
What is the basic unit of the kidney?
Nephron
Where does the filtered content go after passing through the glomerulus?
Through the renal tubule
What is the role of the renal tubule?
To regulate the balance of fluid and ions
What type of diuretics acts on the loop of Henle?
Loop diuretics
What is the final destination of the fluid that goes through the distal convoluted tubule?
The collecting duct
Which of the following is the most ototoxic loop diuretic?
Ethacrynic acid
What is the mechanism of action of loop diuretics in the thick ascending limb?
Inhibiting the Na+K+2Cl- cotransporters
What electrolyte imbalance is associated with the broken magnet in the picture?
Hypomagnesemia
Which of the following is NOT an indication for the use of loop diuretics?
Diabetic nephropathy
What is the effect of loop diuretics on calcium excretion?
Increased calcium excretion
Which of the following is a common side effect of loop diuretics?
Hypokalemia
What percentage of the filtered sodium is reabsorbed in the loop of Henle, mostly in the thick ascending limb?
25%
What is the primary function of the Na/K ATPase on the basolateral side of the tubule cell?
Pump three sodium ions into the interstitial fluid in exchange for two potassium ions
How do loop diuretics affect the reabsorption of sodium, potassium, and chloride in the thick ascending limb?
They bind to the Cl- site on the transporter and block it, preventing reabsorption
What is the effect of loop diuretics on calcium excretion compared to thiazide diuretics?
Loop diuretics increase calcium excretion, while thiazide diuretics decrease it
What is the primary mechanism by which loop diuretics increase the renal plasma flow and glomerular filtration rate?
They stimulate the release of prostaglandins
What is the effect of NSAIDs on the efficacy of loop diuretics?
They decrease the efficacy of loop diuretics
What is the primary mechanism by which loop diuretics cause hypokalemic metabolic alkalosis?
Increased excretion of potassium and hydrogen ions in the urine
What is the major indication for the use of loop diuretics?
All of the above
What is the primary reason for avoiding loop diuretics in dehydrated patients?
Risk of exacerbating dehydration
What is the effect of loop diuretics on the body's water balance?
They decrease the body's water retention
What is the primary site of action for loop diuretics in the nephron?
Thick ascending limb of the loop of Henle
What is the primary mechanism by which loop diuretics lower blood pressure?
They decrease the plasma volume and cardiac output
What is the function of the Na+K+2Cl- cotransporter in the thick ascending limb?
To reabsorb sodium, potassium, and chloride from the lumen
Which of the following is a contraindication for the use of loop diuretics?
Dehydration
What is the primary mechanism by which loop diuretics cause hyperuricemia?
Increased reabsorption of uric acid in the proximal tubule due to low circulating fluid volume
Which of the following is a side effect unique to ethacrynic acid?
None of the above
What is the primary mechanism by which loop diuretics cause hypomagnesemia and hypocalcemia?
Increased excretion of magnesium and calcium in the urine
Which of the following is a drug that is not a sulfonamide loop diuretic?
Ethacrynic acid
What is the primary reason for using ethacrynic acid in patients with a sulfonamide allergy?
It is a safer alternative to sulfonamide loop diuretics in patients with a sulfonamide allergy
What is the primary mechanism by which loop diuretics correct hypercalcemia?
Increased excretion of calcium in the urine
What is the primary function of the renal tubule in maintaining homeostasis?
To secrete and reabsorb fluid and ions in order to maintain balance
What is the unique characteristic of potassium sparing diuretics?
They retain potassium, rather than wasting it
What is the structure that filters the blood in the nephron?
Glomerulus
What is the purpose of the microvilli on the apical surface of the tubule cells?
To increase the surface area for reabsorption
What is the final destination of the fluid that goes through the distal convoluted tubule?
The collecting duct
What is the function of the tubule cells in the proximal convoluted tubule?
To secrete and reabsorb fluid and ions
What is the primary site of action of topical carbonic anhydrase inhibitors in the treatment of glaucoma?
Ciliary body in the eyes
What is the primary indication for using acetazolamide in patients with edematous states?
The presence of alkalosis
What is a common side effect of acetazolamide?
Hyperchloremic metabolic acidosis
What is the primary mechanism by which acetazolamide prevents the formation of uric acid stones?
By increasing the pH of the urine
What is a contraindication for the use of acetazolamide?
Patients with hepatic cirrhosis
Where is the enzyme carbonic anhydrase type 4 primarily found?
Among microvilli
What is the effect of administering acetazolamide on urine output?
Mild increase
What is the purpose of administering acetazolamide to patients with cystinuria?
To increase urine pH
What is the role of carbonic anhydrase in the eyes?
To facilitate bicarbonate movement
What is the mechanism by which carbonic anhydrase inhibitors treat glaucoma?
By reducing aqueous humor production
What is the primary site of action of carbonic anhydrase inhibitors in the treatment of glaucoma?
Ciliary body
What is the effect of carbonic anhydrase inhibitors on bicarbonate movement in the kidneys?
Decrease bicarbonate reabsorption
What is the primary use of acetazolamide in edematous states?
To treat alkalosis
Which of the following is a site where carbonic anhydrase is found?
All of the above
What is the effect of carbonic anhydrase inhibitors on urine pH?
Increase urine pH
What is the primary mechanism by which acetazolamide decreases CSF production?
Inhibiting the formation of bicarbonate in the CSF
Why is acetazolamide used in the management of sleep apnea?
It increases the amount of oxygen available in the blood
What is a side effect of carbonic anhydrase inhibitors related to potassium?
Potassium wasting
Why are carbonic anhydrase inhibitors contraindicated in people with cirrhosis?
They decrease the excretion of ammonia in the urine
What is a side effect of large doses of acetazolamide?
Drowsiness and paresthesias
How do carbonic anhydrase inhibitors affect the kidneys?
They increase the excretion of phosphate and calcium
What is a use of acetazolamide in people climbing to high altitudes?
To treat mountain sickness
What is a metabolic effect of carbonic anhydrase inhibitors?
Metabolic acidosis
Why is it important to monitor urine pH when using carbonic anhydrase inhibitors?
To prevent the formation of calcium phosphate stones
What is the mechanism by which acetazolamide decreases CSF pH?
By decreasing bicarbonate production in the CSF
What is the primary site of action of potassium sparing diuretics in the renal tubule?
Cortical collecting tubules
What is the main function of the renal tubule in maintaining homeostasis?
Reabsorption and secretion of ions and water
What is the basic structural unit of the kidney?
Nephron
What is the role of the glomerulus in the nephron?
Filtration of blood
What is the primary difference between potassium sparing diuretics and other types of diuretics?
Effect on potassium levels
Which segment of the renal tubule is responsible for the majority of ion reabsorption?
Proximal convoluted tubule
What is the primary benefit of using aldosterone receptor antagonists in patients who have had a myocardial infarction?
Reducing the rate of remodelling in the heart
What is the main mechanism by which spironolactone treats polycystic ovarian syndrome?
Blocking androgen receptors
What is a common side effect of using potassium-sparing diuretics?
Hyperkalemia
What is the mechanism by which ENaC channel blockers work?
Blocking epithelial sodium channels
What is a rare genetic disease that can be treated with ENaC channel blockers?
Liddle's syndrome
What is a potential side effect of using triamterene?
Kidney stones
What is the main difference between aldosterone antagonists and ENaC channel blockers?
Aldosterone antagonists block aldosterone receptors, while ENaC channel blockers block epithelial sodium channels
What is the main mechanism by which potassium-sparing diuretics treat edema?
Eliminating excess sodium and water from the body while retaining potassium
What is a potential side effect of using aldosterone antagonists?
Antiandrogenic effects
What is the main indication for using amiloride?
Liddle's syndrome
What is the primary function of the H+/ATPase pump in α-intercalated cells?
To pump hydrogen ions into the tubule
What is the effect of aldosterone on principal cells?
It increases the synthesis of ENaCs and Na-K ATPase transporters
What is the mechanism by which potassium sparing diuretics decrease potassium excretion?
By blocking the ENaC channels on the cell membrane
What is the primary indication for the use of potassium sparing diuretics?
Hypertension and edematous states
What is the effect of aldosterone receptor antagonists on sodium reabsorption?
They decrease sodium reabsorption
What is the primary mechanism by which potassium sparing diuretics increase sodium excretion?
By blocking the ENaC channels on the cell membrane
What is the primary site of action of potassium sparing diuretics?
The distal convoluted tubule and collecting duct
What is the effect of potassium sparing diuretics on hydrogen ion secretion?
They increase hydrogen ion secretion
What is the primary mechanism by which aldosterone receptor antagonists treat hyperaldosteronism?
By blocking the action of aldosterone
What is the primary indication for the use of aldosterone receptor antagonists?
Hyperaldosteronism and hypokalemia
What is the primary function of the renal tubule in maintaining homeostasis?
Reabsorption of electrolytes and ions
Which part of the nephron is responsible for filtering the blood?
Glomerulus
What is the destination of the fluid that passes through the distal convoluted tubule?
Collecting duct
What is the site of action of thiazide and thiazide-like diuretics?
Distal convoluted tubule
What is the primary function of the glomerulus?
Filtering the blood
What is the purpose of the renal tubule in the nephron?
To reabsorb electrolytes and ions
What is the primary mechanism by which thiazides decrease uric acid excretion in the kidneys?
They compete with uric acid for secretion in the proximal convoluted tubule
What is the primary site of action of thiazides in the nephron?
Distal convoluted tubule
What is the primary indication for the use of thiazides in patients with calciuria?
To prevent calcium nephrolithiasis
What is the effect of thiazides on sodium reabsorption in the distal convoluted tubule?
They decrease sodium reabsorption
What is the primary mechanism by which thiazides increase calcium reabsorption in the distal convoluted tubule?
They increase the activity of the sodium-calcium exchanger
What is the primary difference between thiazides and thiazide-like diuretics?
Their chemical structure
What is the primary indication for the use of thiazides in patients with nephrogenic diabetes insipidus?
To treat nephrogenic diabetes insipidus
What is the effect of thiazides on uric acid levels in the blood?
They increase uric acid levels
What is a common side effect of thiazides related to glucose metabolism?
Hyperglycemia
What is the primary mechanism by which thiazides cause hypovolemia?
They increase urine output
What is the primary mechanism of action of thiazide diuretics?
Inhibit the sodium-chloride symporter in the distal convoluted tubule
What is the effect of thiazide diuretics on potassium levels in the blood?
Decrease potassium levels by increasing potassium excretion
What is the primary indication for the use of thiazide diuretics?
Hypertension
What is the effect of thiazide diuretics on calcium levels in the urine?
Decrease calcium levels in the urine
What is the common side effect of thiazide diuretics in people with sulfonamide allergies?
Allergic reaction
What is the effect of ADH on sodium concentration in the blood?
Decrease sodium concentration in the blood
What is the term for low serum potassium levels and high blood pH?
Hypokalemic metabolic alkalosis
What is the name of the thiazide-like diuretic that is represented by a metallic laser gun in the mnemonic?
Metolazone
What is the term for the increased concentration of uric acid in the blood?
Hyperuricemia
What is the primary mechanism by which thiazide diuretics correct nephrogenic diabetes insipidus?
Increase water reabsorption in the collecting duct
What is the primary mechanism of action of mannitol as an aquaretic diuretic?
Decreasing water reabsorption in the proximal convoluted tubule and thin descending limb
What is the main therapeutic use of osmotic diuretics like mannitol?
Lowering intraocular pressure in glaucoma and before ophthalmologic procedures
How does mannitol's osmotic activity affect the kidneys?
It decreases sodium reabsorption and increases water excretion
What is the effect of mannitol on electrolyte balance?
It promotes water excretion without significantly affecting electrolyte balance
What is the fate of mannitol after IV administration?
It is secreted by the glomerulus into the renal tubule
What is the effect of mannitol on the renal tubule?
It decreases water reabsorption in the proximal convoluted tubule and thin descending limb
What is a potential side effect of mannitol when it first enters the bloodstream?
Hyponatremia
Why is mannitol used to treat rhabdomyolysis and hemolysis?
To increase renal blood flow and flush out harmful substances
What is a potential complication of mannitol use in patients with congestive heart failure?
Pulmonary edema
What is a potential electrolyte imbalance that can occur when mannitol increases urine production?
Hypernatremia and hyperkalemia
What is the primary mechanism by which mannitol exerts its effect?
Increasing osmolality of the urine
Why is it important to ensure adequate water replacement when mannitol is used?
To prevent dehydration
Study Notes
Diuretics and the Kidneys
- Diuretics are medications that act on the kidneys to increase production of urine, thereby eliminating water from the body.
- The basic unit of the kidney is called a nephron, which is made up of a glomerulus and a renal tubule.
- The renal tubule has several segments: proximal convoluted tubule, loop of Henle (thin descending, thin ascending, and thick ascending limbs), and distal convoluted tubule, which empties into the collecting duct.
Thiazide and Thiazide-like Diuretics
- Act on the distal convoluted tubule to increase urine output.
- Decrease sodium reabsorption, leading to increased calcium reabsorption and decreased uric acid secretion.
- Used to treat hypertension, edematous states, calciuria, osteoporosis, and nephrogenic diabetes insipidus.
- Side effects: hyperglycemia, hyperlipidemia, hyperuricemia, hypercalcemia, hyponatremia, hypokalemic metabolic alkalosis, and sulfa allergies.
Loop Diuretics
- Act on the thick ascending limb of the loop of Henle to increase urine output.
- Inhibit Na+K+2Cl- cotransporters, leading to increased excretion of sodium, potassium, chloride, calcium, and magnesium.
- Used to treat edematous states, hypertension, hypercalcemia, hyperkalemia, and bromide, iodide, or fluoride intoxications.
- Side effects: ototoxicity, hypokalemia, hypocalcemia, hypomagnesemia, hyperuricemia, and allergic reactions to sulfonamide derivatives.
Key Differences
- Thiazide diuretics decrease calcium excretion, while loop diuretics increase calcium excretion.
- Loop diuretics are more potent in their diuretic effect and are used to treat edematous states and acute intoxifications.
Mnemonics
- Thiazide diuretics: a psychic holding a seance for thiazide-like diuretics, with objects representing indications and side effects.
- Loop diuretics: a rollercoaster with a big loop, a salt shaker, a banana, and 2 swimmers for Na+K+2Cl- cotransporters, and a hot spring with sulfuric smell for sulfonamide loop diuretics.### Osmotic Diuretics
- Osmotic diuretics, like mannitol, increase urine production by pulling water into the renal tubule, reducing sodium reabsorption.
- Act in the proximal convoluted tubule and thin descending limb of the nephron, where they are freely permeable to water.
- As a result, water stays in the tubule, increasing flow rate and reducing sodium reabsorption, leading to a sodium loss and a greater water loss (aquaretic diuretic).
- Used to treat glaucoma and increased intracranial pressure, and to flush out harmful substances (e.g., myoglobin, hemoglobin) from the kidney.
Carbonic Anhydrase Inhibitors
- Inhibit carbonic anhydrase enzyme, reducing bicarbonate reabsorption in proximal tubules.
- Cause mild diuresis, making them useful for edematous states when alkalosis is present.
- Used to treat glaucoma, mountain sickness, and cystinuria, and to prevent kidney stone formation.
Diuretics
- Increase urine production, eliminating water and electrolytes from the body.
- There are five main types: carbonic anhydrase inhibitors, osmotic diuretics, thiazide and thiazide-like diuretics, loop diuretics, and potassium-sparing diuretics.
Potassium-Sparing Diuretics
- Act on cortical collecting tubules, increasing potassium levels in the cell and reducing sodium reabsorption.
- Used to treat hypertension and edematous states, and in combination with other diuretics to reduce potassium loss.
- Aldosterone receptor antagonists (e.g., spironolactone, eplerenone) are used to treat hyperaldosteronism.
Nephron Structure and Function
-
The basic unit of the kidney, consisting of a glomerulus, renal tubule, and peritubular capillaries.
-
The renal tubule has several segments, including the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
-
Each segment plays a role in the reabsorption and secretion of fluids and ions to maintain homeostasis.### Potassium Sparing Diuretics
-
Potassium sparing diuretics eliminate excess sodium and water from the body while retaining potassium.
-
They act in two ways: aldosterone receptor antagonists and ENaC channel blockers.
Aldosterone Receptor Antagonists
- Include spironolactone and eplerenone.
- Block aldosterone receptors on the collecting tubule principal cells.
- Cancel out aldosterone's physiological effects.
- Reduce mortality after a myocardial infarction by reducing remodelling in the heart.
- Bind to androgen receptors, preventing testosterone from binding, making them useful for blunting testosterone effects in polycystic ovarian syndrome.
- Symptoms of polycystic ovarian syndrome include infertility, hair loss, acne, and hirsutism.
ENaC Channel Blockers
- Include amiloride and triamterene.
- Block epithelial sodium channels.
- Useful in treating Liddle's syndrome, a rare genetic disease where ENaC channels are continuously activated, causing sodium retention and renal potassium wasting.
Side Effects
- Hyperkalemia (too much potassium in the blood) can lead to arrhythmias.
- Use of potassium-sparing diuretics with potassium supplements or other medications that increase potassium (ACE inhibitors or ARBs) should be monitored closely.
- Metabolic acidosis can occur due to a buildup of hydrogen ions in the blood, lowering blood pH.
- Rare side effects of spironolactone include antiandrogenic effects like gynecomastia and impotence.
- Triamterene can form kidney stones due to its low solubility and may induce acute renal failure when associated with indomethacin, an NSAID.
Learn about the different types of diuretics, their mechanism of action, and how they affect kidney function. This quiz covers the basics of nephrons, glomerulus, and more.
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