PPT 15: Diuretics Flashcards

Exam 3

1
Q

What are the Proximal Tubule Targets?

A

NaCl and NaHCO3

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2
Q

Which drugs target Proximal Tubule Targets?

A

Carbonic anhydrase inhibitors (block NaHCO3 reabsorption)

Caffeine (weakly blocks adenosine receptors in PCT (Na+))

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3
Q

_______ is an example of a Carbonic anhydrase inhibitor

A

Acetazolamide

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4
Q

Body fluids are kept at a constant osmolality of _____ via a _________ mechanism in the ____

A

300 mOsm/kg
countercurrent
proximal tubule

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5
Q

The _____ is responsible for the secretion of larger substances (drugs) into luminal fluid

A

S2 - straight segment

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6
Q

______ is an impermeable solute that increases osmolality

A

mannitol

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7
Q

The _______ loop of henle is responsible for water reaborption

A

descending

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8
Q

The ______ loop of henle is impermeable to water

A

ascending

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9
Q

What is the pump that transports NaCl in the ascending loop of henle?

A

NKCC2 - sodium, potassium, 2 chloride
- all pumped from urine to thick ascending limb

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10
Q

The excess ____ in the urine of the ascending loop of henle drives ____ out of the urine and into the blood

A

K+ (charge gradient)
Mg++ and Ca++

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11
Q

What is the MOA of loop diuretics? What is an example?

A

Selectively inhibit NaCl reabsorption in the thick ascending limb (TAL)
- Reduction in NaCl absorption
- Diminish lumen positive potential - Increase secretion (loss) of Mg2+ and Ca2+ in urine

Lasix

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12
Q

What diruertics should be avoided in patients with sulfa alergies?

A

Loop diuretics (lasix) and thiazides (HCT)

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13
Q

What is reabsorbed in the distal convoluted tubule? By what?

A

Ca++, by PTH

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14
Q

What is the MOA of thiazides?

A
  • Inhibit NaCl transport in DCT
  • Some inhibition of CA activity
  • HCT
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15
Q

Carbonic anhydrase inhibitors ___ pH, while loop diuretics and thiazides ___ pH

A

Decrease, increase

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16
Q

______ is the final site for sodium reabsorption

A

collecting tubule

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17
Q

______ is the most important site for potassium secretion

A

collecting tubule

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18
Q

The collecting tubule contains what 2 cell types?

A

Principal and intercalated

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19
Q

What is the role of the principal cells in the collecting tubule?

A

Builds up (-) charge in lumen
- more Na+ in than K+ out
- drives Cl- out through paracellular route

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20
Q

_____ is the channel responsible for Na+ and water reuptake in the collecting tubule

A

ENaC - epithelial sodium channel

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21
Q

What is the role of the intercalated cells in the collecting tubule?

A

H+ removal into urine
Exchange bicarb for Cl- in blood

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22
Q

Differentiate between the 2 types of K+ wasting diuretics

A

Some block NaCl
- Cl- leaves via paracellular route
Some block NaHCO3
- HCO3 can’t exit via paracellular route
- Drives increased K+ depletion

23
Q

Diuretics upstream result in excess ___ in CT

A

Na+

24
Q

Aldosterone is secreted by the ______

A

adrenal cortex

25
Q

What is the effect of aldosterone at the collecting tubule?

A

Increase Na+ and water reuptake (ENaC) - increasing BP and vol

26
Q

K+ sparing diuretics work by what MOA?

A
  1. Antagonize the effects of aldosterone - spironolactone
  2. Inhibition of sodium flux through ion channels in luminal membrane - amiloride
27
Q

K+ sparing diuretics are most useful in states of _____

A

mineralocorticoid excess - Conn’s syndrome, Ectopic ACTH production

28
Q

ADH (vasopressin) effects at the collecting duct

A
  • Increases water reabsorption
  • Adds preformed AQP2 to apical membrane
  • Increases blood volume
  • Makes more concentrated urine
29
Q

ADH agonist vs antagonist

A
  • Agonist: Vasopressin
  • Antagonist: Conivaptan
30
Q

What parts of the nephron are freely permeable to water?

A

PCT and descending loop

31
Q

_____ is used mainly to reduce intracranial pressure

A

mannitol
- also for rhabdomyolysis and radiocontrast agents

32
Q

Mannitol works by countering the _____

A

osmotic force - more urine ouput, less Na+ reabsorption

33
Q

What is the etiology and treatment for DI?

A

Insufficient ADH
Thiazide diuretics

34
Q

The hypertonic medullary interstitium is in the _____

A

descending loop of henle

35
Q

What are the uses for Carbonic Anhydrase Inhibitors?

A

Glaucoma
Alkalinization of urine
Metabolic alkalosis
Acute Mountain Sickness

36
Q

What is the loop diuretic that isn’t a sulfanamide?

A

Ethacrynic acid

37
Q

What are the 3 ways GFR is regulated?

A
  1. Adjust blood flow
  2. Alter capillary surface area
  3. Control arteriole diameter
38
Q

What are the steps that occur if GFR is increased?

A

GFR increased
1. Receptors - macula densa cells of JGA detect increased NaCl and water
2. Juxtoglomerular apparatus is the control center - decreased secretion of NO
3. Effectors - afferent arteriole decreases blood flow through the glomerulus
4. GFR decreased - back to homeostasis

39
Q

What are the actions of the nephron?

A
  1. Glomerular filtration
  2. Tubular reabsorption
  3. Tubular secretion
40
Q

Rate of excretion =

A

Rate of excretion = filtration rate + secretion rate - reabsorption rate

41
Q

Most of the filtrate is reabsorbed in the ____

A

PT

42
Q

What are the components of the neprhon?

A
  1. Glomerulus
  2. PCT
  3. Descending loop of henle
  4. Ascending loop of henle
  5. DCT
  6. Collecting tubule
  7. Collecting duct
43
Q

______ is the hormone that acts at the collecting tubule, while _____ is the hormone that acts at the collecting duct

A

aldosterone
ADH

44
Q

What are the 4 main targets of diuretics?

A
  1. Membrane transport proteins
  2. Water permeable segments of nephron
  3. Enzyme inhibition
  4. Interference with hormone receptors
45
Q

What are the classes of diuretics?

A
  • Carbonic Anhydrase Inhibitors
  • Loop Diuretics
  • Thiazides
  • Potassium Sparing Diuretics
  • Osmotic diuretics
46
Q

The renal corpuscle is made of what 2 parts?

A
  1. glomerular capillaries (glomerulus)
  2. glomerular (Bowman’s) capsule
47
Q

The _______ is the capillary system that surrounds the PCT and DCT, while the _____ surrounds the loop of henle

A

Peritubular capillaries
vasa recta

48
Q

Podocytes are only found in the ____

A

cortex - glomerular filtration

49
Q

The juxtaglomerular apparatus includes what 3 parts?

A

macula densa, juxtaglomerular cells, and extraglomerular mesanginal cells

50
Q

The juxtaglomerular apparatus is located where?

A

the vascular pole of the renal corpuscle.

51
Q

How does the juxtaglomerular apparatus regulate BP?

A

Regulates blood pressure by activating the renin-angiotensin-aldosterone system

52
Q

The _____ monitors osmolality and fluid volume in the distal tubule and transmits info to JG cells (NO)

A

macula densa

53
Q

_________ are the modified SM cells in the afferent arteriole that synthesize renin

A

Juxtaglomerular Cells

54
Q

The nephron filters ___ and produces _____

A

blood, urine