Pharmacology Review of Renal Physiology & Diuretics I and II- Grassl Flashcards
TPR x CO =
BP
HR x SV =
CO
Avg GFR is:
125 mL/min
180 L/day
What is the major solute determining ECF osmolarity?
Sodium
More sodium in ECF means larger ECF volume (volume expansion) and vice versa (volume contraction)
How does the kidney maintain ECF in the context of volume expansion?
It decreases reabsorption of sodium and water along the nephron (there is NO secretion of sodium)
Approximately 66% of the filtered sodium and most of the filtered bicarbonate is reabsorbed in the:
proximal tubule
Most of the filtered nutritive solutes (glucose etc) are reabsorbed in the proximal tubule and returned to the circulation in the renal vein.
T/F: Reabsorption of solutes and water in the proximal tubule occurs isosmotically.
True
Approximately 25% of the filtered sodium is reabsorbed in the ________
thick ascending limb of the loop of Henle
The thin descending limb of the loop of Henle is permeable to:
WATER
The thick and thin ascensing limb of the loop of Henle is impermeable to:
WATER
even in the presence of ADH
The ________ is the solute transport engine driving and maintaining the counter current multiplication of interstitial solute concentration difference or solute concentration gradient extending from cortex to medulla surrounding the collecting duct.
thick ascending limb of the loop of Henle
What is the water permeability of the distal tubule?
The early distal tubule is impermeable to water. The late distal tubule is permeable to water when induced with ADH.
FF=
Filtration fraction = GFR/RPF = 120/660 = 0.2
Filtration - Reabsorption + Secretion =
Excretion
What increases potassium secretion in the late distal tubule and early collecting duct?
Aldosterone
What is the effect of alkalosis on potassium secretion?
Increases
What is the effect of acidosis on potassium secretion?
Decreases
Why do diuretics increase potassium secretion?
A diuretic-induced increase in tubular fluid flow will increase potassium secretion due to an increase in the outwardly directed potassium gradient across the luminal membrane.
The Na-Cl cotransporter is the target of what kind of diuretics?
Thiazide diuretics
Competitively interact with chloride for occupancy of the chloride binding site in the Na-Cl cotransport protein –> more Na and Cl remaining in the tubular fluid and delivered to the late distal tubule and collecting duct.
The sodium channel in the luminal membrane of the late distal tubule and collecting duct is the target of the diuretics:
Amiloride and Triamterene
These diuretics block and decrease sodium uptake from the tubular fluid, which decreases transcellular sodium reabsorption and increases the amount of sodium in the urine. –> Decreased K in urine, “potassium sparing”
What kind of diuretic is spironolactone?
Potassium sparing
Spironolactone is a competitive inhibitor of aldosterone –> increased sodium and decreased potassium in the urine
