renal part 4

Question 1

how do Osmotic diuretics work?

Answer 1

retain water by increasing osmotic pressure

Question 2

where in the nephron do osmotic diuretics work?

Answer 2

Proximal Tubule

&

descending Loop of Henle

Question 3

how do carbonic anhydrase inhibitors work?

Answer 3

reduce Na+ reabsorption

Question 4

the __________ is the major site of action for carbonic anhydrase inhibitors

Answer 4

proximal tubule

Question 5

how do loop diuretics work?

Answer 5

inhibit Na+ reabsorption via the Na+ K+ 2Cl- symporter

Question 6

where do loop diuretics primarily work on?

Answer 6

act in Thick Ascending Loop

Question 7

________ diuretics block Na+Cl- symporter

Answer 7

thiazide diuretics

Question 8

what part of the nephron do thiazide diuretics work on?

Answer 8

the early distal tubule

Question 9

K+ sparing diuretics work by doing what?

Answer 9

inhibit sodium reabsorption AND potassium secretion

Question 10

what part of the nephron do K+ sparing diuretics effect?

Answer 10

actin in:

late Distal Tubule

Cortical Collecting Duct

Question 11

what are the 2 classes of potassium-sparing diuretics?

Answer 11

1. aldosterone antagonists

2. ENaC blockers

Question 12

what are Aquaretics?

Answer 12

ADH receptor antagonists

Question 13

_______ diuretics act where tubule is freely permeable to water

Answer 13

osmotic

Question 14

osmotic diuretics work by impairing __________ reabsorption

Answer 14

Na+

Question 15

what % of filtered Na+ is excreted when taking an osmotic diuretic?

Answer 15

10% of filtered Na+ is excreted

Question 16

_________ is also not reabsorbed when taking an osmotic diuretic, due to the lack of solvent drag

Answer 16

Calcium

Ca2+

Question 17

what are 2 examples of osmotic diuretics?

Answer 17

1) mannitol

2) glucose

Question 18

what is the effect of inhibiting Carbonic anhydrase in the proximal tubule?

Answer 18

reduces the H+ available for the Na+/H+ antiporter

Question 19

why are Carbonic anhydrase inhibitors most effective in the proximal tubule?

Answer 19

its where about 1/3 of Na+ reabsorption occurs

Question 20

why are Carbonic anhydrase inhibitors not particularly effective?

Answer 20

downstream segments will increase Na+ reabsorption when tubular Na+ increases

Question 21

____________ diuretics Inhibit Na+K+2Cl- symporters in the thick ascending limb

Answer 21

loop diuretics

Question 22

what is the effect of inhibiting Na+K+2Cl- symporters in the thick ascending limb?

Answer 22

• inhibits Na+ reabsorption

- urine leaving loop is not dilute

Question 23

why does the loop diuretic’s ability to stop dilution of urine make it so effective?

Answer 23

no osmotic gradient established in the medulla interstitium so water not reabsorbed along collecting duct

Question 24

Loop diuretics can increase Na+ excretion to as much as _____% of filtered load

Answer 24

25%

Question 25

_______ diuretics block Na+Cl- transporter in the distal tubule

Answer 25

thiazide

Question 26

what percentage of Na+ is excreted when a thiazide diuretic is taken?

Answer 26

5-20% of the filtered Na+ is excreted

Question 27

how do aldosterone antagonists work?

Answer 27

block aldosterone’s ability to increase Na+ transporters in principal cells of the collecting duct & distal tubule

Question 28

aldosterone antagonists must get inside _____ cells to block aldosterone receptors

Answer 28

tubular

Question 29

How do ENaC blockers work?

Answer 29

block Na+ reabsorption across the apical membrane of the collecting duct & distal tubule

Question 30

________ (a ENaC blocker) is secreted into the proximal tubule

Answer 30

amiloride

Question 31

why does the continued use of diuretics lessen their effectiveness?

Answer 31

diuretics decrease ECV, which means compensatory mechanisms get activated

Question 32

diuretics will cause the decreased release of ______________

Answer 32

natriuretic peptides

Question 33

what occurs in the juxtaglomerular apparatus when a diuretic is taken?

Answer 33

- secretes renin - causes increased angiotensin 2 & aldosterone - end result: decreased Na+ excretion

Question 34

why do many diuretics also increase the excretion of K+?

Answer 34

due to: - increased rate of flow of tubular fluid which stimulates K+ secretion - Reduced ECV which stimulates aldosterone production

Question 35

________ balance is affected by all diuretics

Answer 35

Acid-base

Question 36

metabolic acidosis is caused by what class of diuretics?

Answer 36

CA inhibitors and K+ sparing diuretics

Question 37

metabolic alkalosis is caused by which classes of diuretics?

Answer 37

Loop and thiazide diuretics

Question 38

why would K+ sparing diuretics cause metabolic acidosis ?

Answer 38

because H+ secretion in distal tubule and cortical collecting duct is inhibited

Question 39

Except for the K+ sparing diuretics, all other diuretics alter _______ excretion

Answer 39

calcium (Ca2+)

Question 40

which 2 diuretics act in the proximal tubule and reduce reabsorption of calcium in this segment (so excretion is increased)?

Answer 40

Osmotic and CA inhibitors

Question 41

Loop diuretics increase calcium excretion by what mechanism?

Answer 41

by affecting the transepithelial voltage | its normally the driving force for paracellular transport of calcium

Question 42

_________ diuretics stimulate calcium reabsorption in the distal tubule and thus reduce excretion

Answer 42

thiazide

Question 43

the distal tubule reabsorbs ____% of filtered calcium via active transport

Answer 43

9%

Question 44

Patients with chronic renal failure are almost always diagnosed with ________

Answer 44

anemia

Question 45

why does chronic renal failure cause anemia?

Answer 45

due inadequate secretion of erythropoietin (EPO) and loss of erythrocytes.

Question 46

EPO produced by ________________ in renal cortex

Answer 46

interstitial fibroblasts

Question 47

when is EPO production stimulated?

Answer 47

when PO2 is low

Question 48

what does EPO stimulate?

Answer 48

EPO stimulates differentiation of erythrocyte progenitor cells in the bone marrow

Question 49

EPO production is controlled at the ____________ level

Answer 49

transcriptional

Question 50

T/F: hypoxia-inducible factors 1 and 2 (HIF-1 and HIF-2) are produced when there is a drop in PO2

Answer 50

FALSE they are continually produced

Question 51

why do HIF-1 and HIF-2 not continually act as transcription factors?

Answer 51

they are targeted for degradation when O2 normal