Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Urinary > Diuretics > Flashcards

Diuretics Flashcards

(83 cards)

Start Studying
1
Q

What is a diuretic?

A

A substance/drug that promotes a diuresis

By increasing the renal excretion of water AND sodium, thereby resulting in a reduction of the ECF volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is diuresis?

A

Increased formation of urine by the kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Give some examples of conditions where diuretics would be clinically useful?

A

Heart failure
Cirrhosis
Nephrotic syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do Diuretics work?

A

Act by blocking reabsorption of sodium and water by the tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the normal fraction of excretion of Na?

A

usually <1%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What effect do diuretics have on the Fraction Excretion of Na? (usually <1%)?

A

They increase the FE of Na

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Briefly describe the tubular reabsorption of Na.

A
  • Na+ is pumped out of the cell across the basolateral membrane by Na+K+ATPase
  • Na+ then moves across the apical membrane down its concentration gradient
  • this movement of Na utilizes a membrane transporter or channel on the apical membrane
    (water moves down conc. gradient created by transport of Na)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where are the Na+K+ATPpase transporters found?

A

On the basolateral membrane. Common to all segments of the tubule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What Na+ transporters are present on the apical membrane of the PCT?

A

Na-H antiporter

Also symporters Na-Glucose, Na-AA etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What Na+ transporters are present on the apical membrane in the loop of henle?

A

Na-K-2Cl symporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What Na transporters are present on the apical membrane of the early part of the DCT?

A

Na-Cl symporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What Na+ transporters are available in the later DT and the CD? (principle cells))

A

ENaC (Epithelial Na Channels)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where in the tubule are principle cells located and what Na+ channel is present on the apical membrane?

A

Late part of the DT and the CD

ENaC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the mechanism of Na+ reabsorption and K+ secretion in the principle cells of the late DT and the CD?

A
  • Na+-K+-ATPase in basolateral membrane pump out Na+
  • Na+ enters the cell via ENaC
  • Na+ reabsorption favours K+ secretion by creating a lumen negative potential
  • K+ secreted through K+ channels (down electrochemical gradient)
  • Aldosterone increases expression of Na_K-ATPase, ENaC and K+ channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do diuretics block in the pirnciple cells in the late DT and the CD?

A

ENaC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What affect on K+ secretion does blocking ENaC have on K+ secretion?
Why?

A

Reduces K+ secretion

Reabsroption of Na+ into the cell across the apical membrane via ENaC results in secretion of K+ down as it creates a negative potential in the lumen. Blocking of ENaC reduces the Na+ reabsorption and therefore doesnt promote the secretion of K+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What diuretics act on the proximal tubule?

A 
Cabonic anhydrase inhibitors (Acetazolamide)
Osmotic diuretics (also act at other sites of water absorption) (Mannitol)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What diuretics act on the Loop of Henle?

A

Loop diuretics (Furosemide, Bumetanide)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What diuretics act in the DCT?

A

Thiazide diuretics, metalozone, indapamide, others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What diuretics act in the Collecting Duct?

A

Potassium sparing diuretics (ENaC blockers: Amiloride

Aldosterone antagonists: Spironolactone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where in the kidney do loop diuretics act?

Examples include?

A

Loop of Henle

Furosemide and Bumetanide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where in the kideny do Thiazide diuretics act?

A

DCT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where in the kideny does amiloride act?

What type of diuretic is it?

A

CD

Potassium Sparing Diuretic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What Na+ channel does Amiloride act on?

What type of diuretic is it?

A

ENaC

Potassium sparing diuretics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Where do aldosterone antagonists act? | Example includes?
CD | Spiranolactone
26
Where does Spironolactone act?
CD
27
What transporter do Thiazide Diuretics affect?
Inhibit Na-Cl co-transporter In the Early DT
28
What Na+ channels do Loop diuretics inhibit?
Na+-K+-2Cl co-transporter in the Loop of Henle
29
What Na+ channels do K= Sparing Diuretics act on?
Inhibit ENaC in the late DT and CD
30
What are the four mechanisms by which diuretics work?
1) By direct action on cells to block Na+ transporters on the apical membrane (luminal membrane) 2) By antagonising the action of aldosterone 3) By modification of filtrate content- osmotic diuretics 4) By inhibiting activity of enzyme Carbonic anhydrase
31
Where does Aldosterone act?
On the principal cells of the Late DT and CD to increase reabsorption via ENaC
32
What do Aldosterone antagonists do?
Competitive inhibition of aldosterone receptor on the principal cells in the late DT and CD resulting in decreased Na+ reabsorption
33
How do osmotic Diuretics work? | Tip: Modification of filtrate
Small molecules freely filtered at glomerulus but not reabsorbed, this increases osmolarity of filtrate reducing water and Na+ reabsorption throughout the tubule
34
What does Acetazolamide do? | Tip: Acts in PCT
Inhibits Carbonic Anhydrase in PCT increase excretion of bicarbonate with accompanying Na+, K+ ions and water, resulting in an increased flow of an alkaline urine and metabolic acidosis.
35
Carbonic anhydrase inhibitor Acetazolamide is no longer used as a diuretic, what is is tcommonly used to treat?
Glaucoma- to reduce aqueous humour | Infantile epilepsy
36
Why is the diuretic effect of carbonic anhydrase self limiting?
The urinary loss of bicarbonate depletes extracellular HCO3-, the diuretic effect of carbonic anhydrase is therefore self limiting
37
What % of Na+ is reabsorbed in the Loop of Henle?
25% | Na-K-2Cl transporter
38
Why does the lumen have a positive potential comapred to the blood in the loop of henle?
The K+ move back into the lumen via the K+channels (electrochemical gradient created by movement of Na+ into the cell and the NA+-K+ATPase continuously provind the cell with K+)
39
What helps to drive the reabsorption of positively charged ions Ca2+ and Mg2+ in the loop of henle?
The positively charged lumen (created by K+)
40
Which diuretics are considered the most potent?
Loop Diuretics
41
Where are loop diuretics secreted into the lumen?
in the PCT (via the organic anion pathway) | Travel downstream to act of the loop of henle
42
What clinical condition are loop diuretics often used in?
Heart failure Fluid retention and oedema in: - Nephrotic syndrome - Renal failure - Cirrhosis of liver (spironolactone preferred in cirrhosis, loop diuretics added if necessary) Useful in treatment of hypercalcaemia - Impairs calcium absorption in the loop henle - increases urinary excretion of calcium - Furosemide given together with IV fluids
43
What benefit do loop diuretics have in a patient with heart failure?
Diuretic effect | Also effect vascular SMC--> Vaso and Venodilation (decrease after/preload)
44
Loop diuretics are used to treat flui retention and oedama in?`
Nephrotic syndrome Renal Failure Cirrhosis of liver
45
Spironolactone is perferred in _______ and loop diuretics are added if needed
Cirrhosis
46
Why are loop diuretics useful in the treatment of hypercalcaemia?
Impairs Ca2+ absorption in the Loop of Henle Increases urinary excretion of Calcium Furosemide given together with IV fluids
47
What diuretics act on the early Distal Tubule?
Thiazides
48
In relation to Na and Ca what is the difference between the loop of henle and the early diatal tubule?
Blocking Na absorption increases Ca absorption
49
Describe the process of Thiazide diuretics
- secreted into the lumen in the PCT - Travel downstream to act at the DCT - Block Na-Cl transporter in DCT - Increases Na+ (and H2O) loss in urine - reduced Ca loss in urine (i.e increases Ca absorption)
50
Via what transporter are Na ions reabsorbed in the Early DCT?
Na-Cl transporter
51
What transporter do thiazide diuretics block and where?
Na-Cl transporter | Early Distal Tubule
52
Which diuretics are less potent; Thiazides or Loop?
Thiazides
53
Why are Thiazide diuretics less potent than Loop Diuretics?
Only 5% of sodium reabsorption inhibited | In effective in renal failure
54
What are Thiazide diuretics widely used for?
Hypertension (vasodilatation)
55
Thiazides have a higher incidence of ____
Hyperkalaemia
56
What Diuretics act on the Late DCT and the CD?
Potassium sparing diuretics 1) Inhibitors of ENaC -- Amiloride 2) Aldosterone antagonsits -- Spironlactone
57
How much of Na+ reabsorption do K+ sparing diuretics affect?
2% of Na+ reabsorption
58
What life threatening condition can both types of potassium sparing diuretics cause?
Hyperkalaemia
59
What drugs/conditions can result in hyperkalaemia when using potassium sparing diuretics?
- Ace inhibitors - K+ supplements - Patients with renal impairment
60
What drug is best for the treatment of hypertension due to primary hyperalosteronism (Conn's Syndrome)?
Aldosterone antagonists e.g Spironolactone
61
What is Conn's syndrome?
Hypertension due to primary hyperaldosteronism | Adrenal hyperplasia or adrenal tumour --> increased secretion of Aldosterone --> Hypertension
62
What is the preferred drug for Ascites and Oedema in Cirrhosis?
Aldosterone antagonists e.g spironolactone
63
What are Acites?
accumulation of fluid in the peritoneal cavity
64
What diuretics are used in addition to Loop diuretics in heart failure?
Aldosterone antagonists e.g. spironolactone
65
What is used as additional therapy in hypertension which is not controlled by ACEI +CCB+Thiazide
Aldosterone antagonists e.g. spironolactone
66
What is usually used in combination with Loop or Thiazide diuretics and why?
K+ asparing diuretics; ENaC blockers e.g Amiloride. | Minimise the loss of K+
67
What are the 4 main classes of Diuretics?
- Loop diuretics - Thiazide Diuretics - K+ sparing Diuretics - Aldosterone Antagonists
68
Are inhibitors or carbonic anhydrase used as diuretics?
No
69
Are Osmotic Diuretics used as diuretics currently?
No
70
Where do Carbonic anhydrase inhibitors act?
PCT
71
What is an example of a carbonic anhydrase inhibitor?
Acetazolamide
72
Describe the action of Carbonic anhydrase inhibitors
- > Inhibits action of carbonic anhydrase in bursh border and PCT cell - > Can cause metaboic acidosis due to loss of HCO3- in urine - > Useful in the treatment of Glaucoma - > Reduces formation of aqueous humor in eye by about 50%
73
What is Mannitol?
Osmotic Diuretic
74
Describe Mannitol
Osmotic diuretic: - Small molecule - Increases plasma osmolarity thus drawing out fluid from tissue and cells - In the kideny increases the osmolarityb of filtrate - Acts by altering the driving force for renal water absorption, which is osmolarity - Causes loss of water, Na+ and K+ in urine - Not inhibitors of enzymes or transport proteins
75
What is IV mannitol useful in treating?
Cerebral Oedema
76
How is K+ secretion driven in the Distal tubule and Collecting duct?
Passive Process driven by electrochemical gradient
77
What does the rate of K+ secretion depend on?
- Concentration gradient across the apical membrane | - Rate of Sodium absorption (inward movement of Na+ ion creates a favourable lumen negative potential for K+ secretion)
78
Why do Loop Diuretics and Thiazides cause hypokalaemia?
Block Na+ reabsorption in the LoH or early DT, so increased NA+ and H2O delivery to the late DT and CD - increased Na absorption by principal cells --> favourable electrical gradient for K+ excretion - fatser flow rate of filtrate in tubuile lume --> washing away K+ maintaining a low conc gradient --> Favourable chemical gradient for K+ secretion
79
In relation to the RAAS how does excess diuresis result in hypokalaemia?
Excess Diuresis reduces ECF volume - --> Activation of RAAS - --> Aldosterone Secretion - --> increased Na Absorption and K+ secretion - --> Hypokalaemia
80
Which Hypo- or Hyper -Kalaemia may occur with K+ sparing Diuretics?
HYPERKalaemia
81
What are the mechanisms behind Hyperkalameia when using K+ sparing diuretics?
ENaC inhibitors reduce reabsorption of Na+ which reduces K+ loss in urine Aldosterone antagonsits block the action of Aldosterone thereby reducing the activty of Na+-K+ATPase reducing Na+ reabsorption and reducing loss of K+ in the urine = HYPERKALAEMIA
82
Sine diuretics can cause hypo and hyper kalaemia what should be done when treating someone with diuretics?
Monitor electrolyte levels during therapy } Combine loop/thiazide diuretic with a K+ sparing diuretic can be used to minimise changes in K+ or combine with K+ supplements
83
When are diuretics used?
Conditions with ECF explansion and Oedema - HF - Cirrhosis - Nephrotic syndrome

Urinary (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions