Physiology diuretics

Question 1

what is a diuretic ?(2)

Answer 1

prompts more urine, decrease bp hence reduces cardiac work

Question 2

what are the 4 types of diuretic and where do they act ?

4

Answer 2

1-osmotic diuretics/ Carbonic Anhydrase inhibitors in Proximal convoluted tubule
2-Loop diuretics (thick ascending loop of Henley)
3-Thiazide diuretics = distal convoluted tubule
4-Potassium sparring diuretics = collecting duct

Question 3

How do osmotic diuretics work? when are they used?
(6) example?
side effects?
what does it stop the reabsorption of?
when is used?
side effects

Answer 3

Works in PCT
EX: MANNITOL

Mode of actions:
stop the reabsorption of Na+ and HCO3- into blood, hence more water and Na+ retained in the lumen.

Used for: reducing inter-cranial pressure,

Side effects :

• hypotension (low BP)
• fluid and electrolyte disturbance

Question 4

How does carbonic anhydrase inhibitors work ?
case study ( where does it work , what does it do, side effects )?
(6)
side effects (Mehr)

Answer 4

Works in PCT
Mode of action :
No H+ AND HCO3- get filtered into the blood , so they remain in lumen , but this is very weak because they can just get filtered in Distal convoluted tubule later on !

Carbonic anhydrase converts co2 + water –> H+ + HCO3- = controlls pH

Inhibitors are: acetazolamide

• weak diuretics
• used in glaucoma ( oedema in the eye )
• acute Altitude sickness ( you lose co2, so ur body tissue becomes alkaline = hence the drug can speed things up, as it promotes alkaline loss by kidney, more co2 retention, maintains p.H)

Side effects :
Metabolic acidosis
Hypokalemia
Renal stone formation

Question 5

Loop diuretics case study

• where does it work
• examples
• mode of action
• treatments
• side effects

Answer 5

Works in ASCENDING loop of Henley ! Very strong!

Example: FUROSEMIDE , BUMETANIDE , TORASEMIDE

MODE OF ACTION :

• blocks Na+/K+/Cl- channel which means that the Na+ is kept in the lumen –> travels to collecting duct which is more water soluble = more water enters collecting duct via osmosis =water and sodium loss in URINE
• prostaglandins cause dilation of afferent arteriole increasing filtelation

Treats:

• congestive heart failure
• resistant HT
• liver disease
• Kidney syndrome

Side effect:

• hypokalemia
• Damage to ear and kidney
• GOUT
• Allergic reactions

Question 6

Thiazide and thiazide-like drugs case study 
(6)
where does it work?
mode of action?
when to use?
adverse effects? 
drug interaction?

Answer 6

ACT in distal convoluted tubule
weaker diuretic (modest reduction in blood volume )
examples : hydrochlorothiazide, bendroflumethiazide etc

Mode of action :
INHIBITS NaCl transporter protein so Na+ remains in lumen -Na+ and cl- are kept in the lumen
-Ca2+ channels are opened and ca2+ is secreted into the blood instead

When to use:
2nd 3rd line, consider if a person is volume expanded or ca2+ doesn’t work, heart failure, HT

Adverse effects :

• More rate retention =gout
• Increased cholesterol and hyperglycaemia
• reduced ca2+ excretion , more ca2+ in blood
• less damage to ear and kidney

Drug interactions:

• Hypotension with ACE inhibitors
• LI toxicity when prescribed eight lithium
• Hypernatraemia ( na+ increased in the blood ) when prescribed with SSRI anti depressions

Question 7

Potassium-sparing diuretics
(6)
2 main types
adverse effects?

Answer 7

Works in late distal tubule
Mode of action :
There are 2 main types :

1=Na+ channel blockers ( which block the inward na+ channel, used for fine-tuning ), this means Na+ will remain in the lumen and go into the urine but K+ /H+ will remain in the cell

2=Aldosterone receptor antagonist ( spirolactone )= increases Na+ in Lumen and decreases K+/H+ in lumen

-sodium-potassium pump is not synthesised (made) so sodium remains outside and potassium remains inside

Adverse effects :

• Hyperkalaemia (with ACE inhibitors& RAAS blockers)
• metabolic acidosis ( H+ retention)
• spironolactone can cross-react at other steroid hormone receptors interfering with progesterone etc = breast enlargement, Breast pain, facial hair growth, irregular periods )

Question 8

outline the nephron and all of the relevant channels?
5 parts
(6)

Answer 8

1-Glomerulus
2-Proximal convoluted tubule (PCT): CONTAINS Na+/ NaHCO3 channels to filter out water and salt
3-Loop of Henley = contains Na+/k+/2Cl- transporter ions which remove them into the blood
4-Distal convoluted tubule (DCT)= Na+Cl- ion channel to remove them into blood
5-Collecting duct has Na+/K+ pump, where potassium and H+ move into the lumen and Na+ moves out into blood
-Also has Water channels = to reabsorb water into the blood !

Question 9

side effects of the Loop diuretics?

OH DANG

Answer 9

Ototoxicity ( ear damage )
Hypokalemia
Dehydration 
Allergy 
Nephritis 
Gout