Pharmacology Review of Renal Physiology & Diuretics I and II- Grassl

Question 1

TPR x CO =

Answer 1

BP

Question 2

HR x SV =

Answer 2

CO

Question 3

Avg GFR is:

Answer 3

125 mL/min

180 L/day

Question 4

What is the major solute determining ECF osmolarity?

Answer 4

Sodium

More sodium in ECF means larger ECF volume (volume expansion) and vice versa (volume contraction)

Question 5

How does the kidney maintain ECF in the context of volume expansion?

Answer 5

It decreases reabsorption of sodium and water along the nephron (there is NO secretion of sodium)

Question 6

Approximately 66% of the filtered sodium and most of the filtered bicarbonate is reabsorbed in the:

Answer 6

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.

Question 7

T/F: Reabsorption of solutes and water in the proximal tubule occurs isosmotically.

Answer 7

True

Question 8

Approximately 25% of the filtered sodium is reabsorbed in the ________

Answer 8

thick ascending limb of the loop of Henle

Question 9

The thin descending limb of the loop of Henle is permeable to:

Answer 9

WATER

Question 10

The thick and thin ascensing limb of the loop of Henle is impermeable to:

Answer 10

WATER

even in the presence of ADH

Question 11

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.

Answer 11

thick ascending limb of the loop of Henle

Question 12

What is the water permeability of the distal tubule?

Answer 12

The early distal tubule is impermeable to water. The late distal tubule is permeable to water when induced with ADH.

Question 13

FF=

Answer 13

Filtration fraction = GFR/RPF = 120/660 = 0.2

Question 14

Filtration - Reabsorption + Secretion =

Answer 14

Excretion

Question 15

What increases potassium secretion in the late distal tubule and early collecting duct?

Answer 15

Aldosterone

Question 16

What is the effect of alkalosis on potassium secretion?

Answer 16

Increases

Question 17

What is the effect of acidosis on potassium secretion?

Answer 17

Decreases

Question 18

Why do diuretics increase potassium secretion?

Answer 18

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.

Question 19

The Na-Cl cotransporter is the target of what kind of diuretics?

Answer 19

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.

Question 20

The sodium channel in the luminal membrane of the late distal tubule and collecting duct is the target of the diuretics:

Answer 20

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”

Question 21

What kind of diuretic is spironolactone?

Answer 21

Potassium sparing

Spironolactone is a competitive inhibitor of aldosterone –> increased sodium and decreased potassium in the urine