Diuretics Flashcards
What is natriuresis?
Excretion of sodium ions in urine
Which part of the loop of Henle is thick? Which part is thin?
Thin descending limb, thick ascending limb
Where do osmotic agents act?
PCT and thin descending limb of LOH (permeable to water)
Where do loop diuretics act?
Thick ascending limb of LOH
Where do thiazides act?
DCT
Where do potassium-sparing agents act?
Collecting duct
Why do osmotic agents only have limited effects?
Osmotic agents act early on in the nephron (PCT), so the rest of the nephron often compensates for the effect of the drug (counteracts its effects)
Which is the most powerful type of diuretic?
Loop diuretics
Why are thiazides and K-sparing agents relatively weak diuretics?
Act quite late in the nephron, most water reabsorption occurs in LOH
What is the difference between osmolarity and osmolality?
Osmolarity is the osmoles of solute in a litre, osmolality is the osmoles of solute in a kilogram
How do osmotic diuretics/agents act?
Increase osmolarity of tubular fluid in PCT and LOH, which decreases passive reabsorption of water
Give an example of when osmotic diuretics are used?
Cerebral oedema to remove fluid from brain
Give an example of an osmotic diuretic
Mannitol (a sugar, reduces reabsorption of water from PCT)
Give 2 examples of loop diuretics
Furosemide and bumetanide
How do loop diuretics work?
. Inhibit Na+/2Cl-/K+ symporters in thick ascending limb of loop of Henle (so solutes all stay in tubule and so does water)
. Prevents LOH establishing hyperosmotic interstitium
. Powerful diuresis for CHF
