112 Questions
What is the primary function of the Na+/K+ adenosine triphosphatase (ATPase) pump in the proximal convoluted tubule?
Reabsorption of sodium ions
What is the role of carbonic anhydrase in the proximal tubular cells?
Reabsorption of bicarbonate
Where is the organic acid secretory system located and what is its primary function?
Proximal tubule -transfer the diuretic drugs and uric acid
How are most diuretic drugs delivered to the tubular fluid?
By secreting a variety of organic acids from the bloodstream into the proximal tubular lumen
What characterizes the organic acid secretory system?
It is saturable
How do diuretic drugs in the bloodstream interact with endogenous organic acids such as uric acid?
They compete for transfer with endogenous organic acids
What is the primary function of the ascending loop of Henle?
Active reabsorption of Na+, K+, and Cl−
Why does the osmolarity increase along the descending portion of the loop of Henle?
Due to reabsorption of water
What effect do drugs affecting the ascending loop of Henle, such as loop diuretics, have?
Greatest diuretic effect
How much of the filtered sodium chloride is reabsorbed via a Na+/Cl− transporter in the distal convoluted tubule?
10%
What is the primary transporter used for Na+ reabsorption in the collecting tubule and duct?
Na+/K+-ATPase pump
Which receptors influence Na+ reabsorption and K+ secretion in the principal cells of the collecting tubule and duct?
Aldosterone receptors
What is a characteristic of thiazides as diuretic drugs?
They have equal maximum diuretic effects except Metolazone
Why are thiazides sometimes called 'low ceiling diuretics'?
Because increasing the dose above normal therapeutic doses does not promote further diuretic response
What is a distinguishing feature of Metolazone among thiazide-like drugs?
It has higher efficacy than other thiazides
Which of the following is correct for using thiazides except?
Heart failure
Why is hydrochlorothiazide used more commonly than chlorothiazide?
Because it is more potent
What distinguishes the efficacy of hydrochlorothiazide from chlorothiazide?
The efficacy of both drugs is comparable
Why are thiazide-like diuretics referred to as thiazide-like?
They have a similar mechanism of action to true thiazides
What is a distinguishing feature of thiazide-like diuretics?
They contain the sulfonamide residue in their chemical structures
Thiazide-like diuretics are called thiazide-like because they contain the sulfonamide residue in their chemical structures.
True
Thiazide-like diuretics have a different mechanism of action compared to true thiazides.
False
Chlorthalidone, indapamide, and metolazone are examples of thiazide-like diuretics.
True
True thiazides are also known as low ceiling diuretics.
True
Thiazides act mainly in the cortical region of the ascending loop of Henle and the distal convoluted tubule.
True
Thiazides decrease the reabsorption of Na+ by inhibition of a Na+/Cl− cotransporter on the luminal membrane of the tubules.
True
Thiazides are also known as high ceiling diuretics.
False
Thiazide-like diuretics act in the same way as true thiazides in the renal tubules.
False
What is a potential consequence of increased excretion of Na+ and Cl− in the urine due to treatment with thiazides?
Hyponatremia
What is a known effect of prolonged use of thiazides in terms of potassium (K+)?
Hypokalemia
What is a potential consequence of treatment with thiazides in terms of urinary calcium excretion?
Hypercalcemia
What is an initial effect of treatment with thiazides on peripheral vascular resistance?
Reduced peripheral vascular resistance
What is a potential consequence of treatment with thiazides in terms of Mg2+?
Hypomagnesemia
How do thiazides affect the excretion of sodium chloride in the urine?
Increased excretion
Treatment with thiazides can result in the excretion of very hyperosmolar urine.
True
Thiazides cause loss of K+ from the body with prolonged use.
True
Thiazides result in a reduction in peripheral vascular resistance.
True
Thiazides act by increasing the reabsorption of Na+ in the distal convoluted tubule.
False
In which condition are thiazides not the first choice of treatment?
Heart failure
What is the unique ability of thiazides in the treatment of nephrogenic diabetes insipidus?
Substituting for ADH
What is a potential benefit of thiazides for patients with calcium oxalate stones in the urinary tract?
Reducing urinary calcium excretion
What is the most frequent problem associated with thiazide diuretics?
Hypokalemia
Which adverse effect of thiazide diuretics can be prevented by limiting water intake and lowering the diuretic dose?
Hyponatremia
What adverse effect of thiazide diuretics can lead to glucose intolerance and the need for monitoring glucose levels?
Hyperglycemia
What adverse effect of thiazide diuretics can cause orthostatic hypotension or light-headedness?
Volume depletion
Potassium depletion is the most frequent problem with thiazide diuretics.
True
Limiting water intake and lowering the diuretic dose can prevent hyponatremia.
True
Therapy with thiazides can lead to glucose intolerance.
True
What is the primary site of action for loop diuretics in the nephron?
Descending limb of the loop of Henle
What is the reason for loop diuretics having the greatest diuretic effect among all diuretic drugs?
They block reabsorption of 25-30% of filtered NaCl at the ascending limb of the loop of Henle
Which part of the nephron accounts for reabsorption of 25-30% of filtered NaCl?
Ascending limb of the loop of Henle
How does loop diuretics' mechanism of action lead to an increase in water excretion?
By inhibiting the cotransport of Na+/K+/2Cl− at the ascending limb of the loop of Henle
Which of the following is a therapeutic use of loop diuretics?
Reducing acute pulmonary edema and acute/chronic peripheral edema
What is a significant characteristic of loop diuretics in emergency situations?
High efficacy and rapid onset of action
How do loop diuretics differ from thiazides in terms of Ca2+ content of urine?
Thiazides increase the Ca2+ content of urine
What is a therapeutic use of loop diuretics in treating hypercalcemia?
Stimulating tubular Ca2+ excretion
Which loop diuretic is known for being much more potent than furosemide?
Bumetanide
What is the primary reason for the infrequent use of ethacrynic acid?
Adverse effect profile
In which condition are thiazides not the first choice of treatment?
Nephrogenic diabetes insipidus
What distinguishes the efficacy of metolazone among thiazide-like drugs?
Duration of action
Furosemide is the most potent loop diuretic.
False
Ethacrynic acid is commonly used due to its low toxicity.
False
Bumetanide is an example of a loop diuretic.
True
Thiazides cause loss of K+ from the body with prolonged use.
True
Which adverse effect is most likely to be caused by loop Diuretics ?
All of the above
What is a potential consequence of prolonged use of thiazides in terms of potassium (K+)?
Potassium depletion (hypokalemic alkalosis)
Which adverse effect of diuretics can be prevented by using potassium-sparing diuretics or supplementation with K+?
Potassium depletion (hypokalemic alkalosis)
What adverse effect of diuretics can cause a severe and rapid reduction in blood volume, with the possibility of hypotension?
Acute hypovolemia
Which diuretic adverse effect can lead to increased uric acid in the blood, causing or exacerbating gouty attacks?
Hyperuricemia
Which diuretic adverse effect is most likely to cause deafness and is associated with the use of Ethacrynic acid?
Ototoxicity
Which diuretic adverse effect can lead to increased uric acid in the blood, causing or exacerbating gouty attacks?
Hyperuricemia (Increased uric acid in the blood)
What is the primary transporter used for Na+ reabsorption in the collecting tubule and duct?
Potassium-sparing diuretics
What is the primary function of potassium-sparing diuretics?
Prevent K+ excretion caused by thiazide or loop diuretics
Why should potassium-sparing diuretics be avoided in patients with renal dysfunction?
To reduce the risk of hyperkalemia
What are the two distinct mechanisms of action for potassium-sparing diuretics?
Aldosterone antagonism and sodium channel blockers
Which medication should be used cautiously with potassium-sparing diuretics due to its potential to induce hyperkalemia?
Angiotensin-converting enzyme inhibitors
In which conditions are potassium-sparing diuretics commonly used?
Heart failure and liver cirrhosis
What is the major difference in efficacy between potassium-sparing diuretics and other diuretics?
Lower efficacy in mobilizing Na+ from the body
What is the mechanism of action of spironolactone and eplerenone?
Antagonizing aldosterone at intracellular cytoplasmic receptor sites
Which class do spironolactone and eplerenone belong to?
Potassium-sparing diuretics
What distinguishes the mechanism of action of eplerenone from spironolactone?
Eplerenone has less endocrine effects than spironolactone
What is the primary effect of spironolactone and eplerenone on electrolyte balance?
Prevents reabsorption of Na+ and secretion of K+ and H+
What is a therapeutic use of spironolactone?
all of the above
In which condition is spironolactone the diuretic of choice?
Congestive hepatic cirrhosis
What is a therapeutic use of eplerenone?
Treatment of resistant hypertension
Why are aldosterone receptor antagonists considered for the treatment of resistant hypertension?
Due to their role in reducing peripheral vascular resistance
What adverse effects can occur due to the chemical resemblance of spironolactone to some sex steroids?
Gynecomastia in male patients
Which adverse effect is associated with the use of aldosterone antagonists?
Hyperkalemia with nausea, lethargy, and mental confusion
What is a known consequence of prolonged use of thiazides in terms of potassium (K+)?
Loss of K+ from the body
What is the primary effect of triamterene and amiloride on Na+/K+ exchange in the collecting tubule?
Blocking of Na+/K+ exchange
Which property makes triamterene and amiloride commonly used in combination with other diuretics?
Potassium-sparing properties
What distinguishes the mechanism of action of triamterene and amiloride from aldosterone antagonists?
Blockage of sodium channels
What is the primary reason for the use of triamterene and amiloride in combination with other diuretics?
Potassium-sparing properties
What is the primary mechanism of action of acetazolamide?
Inhibition of carbonic anhydrase in the proximal tubular epithelium
What is the consequence of prolonged therapy with acetazolamide?
Hyperchloremic metabolic acidosis
Which electrolyte disturbance is associated with the use of acetazolamide?
Hypercalcemia
What effect does acetazolamide have on phosphate excretion?
Increases phosphate excretion
What is the therapeutic use of acetazolamide?
Treating glaucoma
What is the primary function of carbonic anhydrase inhibitors like dorzolamide and brinzolamide?
Decreasing intraocular pressure
Which condition can be treated by using carbonic anhydrase inhibitors to decrease pH?
Respiratory alkalosis
What is the therapeutic use of eplerenone?
Resistant hypertension
What is a potential adverse effect of using acetazolamide?
Metabolic acidosis
Why should acetazolamide be avoided in patients with hepatic cirrhosis?
It might cause decreased excretion of NH4+
Which adverse effect is associated with the use of thiazides?
Hyperuricemia
What is a potential adverse effect of diuretics that can cause orthostatic hypotension or light-headedness?
Potassium depletion
What is the primary mechanism of action of osmotic diuretics?
Increased water excretion by preventing further water reabsorption in the tubules
What is the effect of osmotic diuretics on tubular fluid osmolarity?
It increases tubular fluid osmolarity
What is the role of simple, hydrophilic chemical substances such as mannitol and urea in osmotic diuretics?
They are filtered through the glomerulus and undergo reabsorption
How do osmotic diuretics differ from other diuretics in terms of their primary effect on electrolyte balance?
They primarily increase water excretion rather than Na+ excretion
Osmotic diuretics prevent further water reabsorption, resulting in some degree of diuresis.
True
Osmotic diuretics directly increase the excretion of electrolytes.
False
Osmotic diuretics undergo significant reabsorption in the nephron.
False
Explore the kidney's active reabsorption and secretion of ions, as well as passive reabsorption of water in different functional zones along the nephron. Understand the regulation of ionic composition and urine volume.
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