Renal Flashcards
What ion is the main contributor to water movement into and out of the nephron?
Sodium
Why are diuretics used?
- To mobilize tissue fluid (edema/ascites)
- To reduce blood volume (hypertension or congestion)
- To protect kidney function (restore urine flow or remove toxins)
What are the major classes of diuretics?
- Carbonic anhydrase inhibitors
- Osmotic diuretics
- Loop diuretics
- Thiazide diuretics
- Potassium sparing diuretics
What is natriuresis?
The excretion of sodium in urine.
What is the term for sodium loss in urine?
Natriuresis
How do diuretics increase water excretion?
Inhibit targets that play a role in tubular sodium reabsorption. With increased sodium excretion, water passively follows.
Which target area has the biggest impact on modifying sodium absorption?
Loop of Henle
This is because the loop of Henle can compensate for changes in proximal tubule reabsorption.
How much sodium is reabsorbed? Where does the reabsorption occur?
Majority of sodium is reabsorbed, only 1-5% is excreted.
Most sodium is reabsorbed in the proximal tubule (45-65%), then rest is reabsorbed in the loop of Henle (25-40%) and distal tubule and collecting duct (10%).
What is the site of action of carbonic anhydrase inhibitors?
Proximal tubule.
What is the site of action of osmotic diuretics?
Descending loop of Henle.
What is the site of action of loop diuretics?
Thick ascending loop of Henle.
What is the site of action of thiazide diuretics?
Distal tubule.
What is the site of action of potassium-sparing diuretics?
Collecting duct.
Do diuretics work from inside or outside of the tubular lumen?
All except for spironolactone are active inside of the lumen so must reach an adequate tubular concentration to be effective.
Plasma concentration does not impact effect.
What is the primary mechanism of action of carbonic anhydrase inhibitors?
Interact with enzymes.
Inhibits carbonic anhydrase.
