ADH and Diuretics Flashcards
How much plasma is filtered by the kidneys in a day?
180 L
Where in the kidney do the loop diuretics work?
the ascending limb of the LOOP of henle (LOOP)
Where in the nephron do thiazide diuretics work?
in the distal convoluted tubule
Where in the nephron do Potassium sparing diuretics work?
the cortical collecting tubule
Where is ADH active?
in the medullary collecting duct
Where in the nephrone do the osmotic diuretics work?
in the proximal tubule and/or the descending limb of the LOH
What are two examples of Loop diuretics?
furosemide (Lasix) and bumetanide
What do loop diuretics do?
they inhibit the Na/K/2 Cl pump in the thick ascending limb of the lOH
What percentage of Na is reabsorbed in this area - the thick ascending limb of the LOH?
about 25%
WHat happens in general to the osmolarity in the tubule of the thick ascending limb of the LOH?
It goes hypo-osmolar because Na, K and Cl are pumped out but water remains inside since there are no aquaporins here
What is the effect of the loop diuretics on osmolarity within the tubulet hen?
They prevent this decrease in osmolarity because they inhibit the Na, K and Cl from moving out of the tubule.
What effect do the loop diuretics have on Na, Cl and K excretion?
Increased NaCl excretion and increased K excretion because some of the increased nehron Na is exchanged for K in the cortical collecting tubule
What are the major uses of loop diuretics?
- pulmonary edema
- other edematous conditions (CHF)
- hyperkalemia
- acute renal failure
- anion overdose
Why aren’t the loop diuretics used for HTN?
Because htey have a much greater impact on systemic electrolyte levels than the thiazide diuretics and thus have more severe side effects
What are three thiazide diuretics?
chlorthalidone
hydrochlorothiazide
metalazone
What do the thiazides do?
they block the NaCl transporter in the distal convoluted tubule
What percentage of NaCl reabsorbtion occurs in the distal convoluted tubule?
not much - only 8%.
What do the htiazides to to Na, Cl and K excretion
increased NaCl excretion
increase K excretion because some of the increased Na is exchanged for K in the cortical collecting tubule
What are the major uses of the thiazides?
hypertension!
heart failure
nephrolithiasis caused by hypercalcemia
nephrogenic diabetes insipidus
What are the major side effects of the htiazides?
hyperglycemia hyperuricemia hypokalemia hyperlipidemia hyponatremia allergic reactions
Why do the thiazides cause hyperglycemia? Do you still use them in diabetics?
Thiazides are sulfonylureas and will bind to an SUR receptor on a potassium channel controlling insulin release
when it binds, the K channel opens and you get an efflux of K and you hyperpolarize the beta cell
This inhibits the beta cell’s release of insulin release
thus, increasing blood glucose
What are the potassium sparing diuretics?
spironolactone
eplerenone
amiloride
triamterene
What are the two mechanisms of the K sparing diuretics?
spironolactone and eplerenon are aldosterone receptor inhibitors
amiloride and triamterene inhibit Na exchange for K and H in the cortical collecting duct
What are the major uses of the K sparing diuretics?
hyperaldosteornism
prevent potassium wasting caused by other diuretics
