Diuretics

Question 1

What is the renal mechanism for low BP?

Answer 1

Low NaCl detected by the macula densa cells in the DCT causing renin release which causes aldosterone release so more Na/K pumps

Question 2

Which part of the nephron do loop diuretics act on?

Answer 2

Thick ascending limb of the loop of henle - act on Na/K/2Cl channel

Question 3

Which part of the nephron can PTH act on?

Answer 3

The DCT

Question 4

What is the role of the PCT?

Answer 4

Reabsorption

Question 5

What is the role of the Loop of Henle?

Answer 5

Create osmolarity gradient

Question 6

What is the role of the DCT?

Answer 6

pH and variable Ca reabsorption

Question 7

What is the role of the medullary CD?

Answer 7

pH and K regulation

Question 8

What is the role of the cortical CD?

Answer 8

Regulation of H2O reabsorption

Question 9

What is the endocrine function of the kidneys?

Answer 9

Renin release by juxtaglomerulus apparatus
Erythropoietin synthesis
1 alpha hydroxylation of vitamin D (Controlled by PTH)

Question 10

What is the MOA of Carbonic Anhydrase Inhibitors?

Answer 10

Inhibit Carbonic Anhydrase in the PCT
Used for glaucoma
Can cause drowsiness, renal stones, metabolic acidosis as HCO3 reabsorption decreased
(acetazolamide)

Question 11

What is the MOA of Loop Diuretics?

Answer 11

Inhibit the Na/K/2Cl channel in the thick ascending limb of the LoH.
Mass NaCl, K and Ca loss
Used for treatment of oedema - can be due to CCF, Nephrotic syndrome,Hypercalcaemia.
Can cause hypovolaemia, ototoxicity, hypokalaemic metabolic alkalosis
(fursemide, bumetanide)

Question 12

What is the MOA of Thiazide Diuretics?

Answer 12

Inhibit NaCl channel in DCT
Cause increase in NaCl excretion and increased Ca reabsorption
Used for HTN, mild oedema, renal stones
Cause hypokalaemia, increased urate -> Gout, hyperglycaemia
(bendroflumethazide)

Question 13

What is the MOA of K-Sparing Diuretic - spironolactone?

Answer 13

Aldosterone antagonist
Increases Na secretion, decreases K and H secretion
Mainly used in conjunction with loop or thiazide diuretics to prevent hypokalaemia
Increase K so may cause hyperkalaemia, anti-androgenic
Especially good in patients with HF or liver failure

Question 14

What is the MOA of K-Sparing Diuretic - amiloride?

Answer 14

Blocks epithelial Na channels in DCT/CD
Increases Na secretion, decreases K and H secretion
Mainly used in conjunction with loop or thiazide diuretics to prevent hypokalaemia
Increase K so may cause hyperkalaemia, anti-androgenic

Question 15

Where is Aldosterone secreted?

Answer 15

Zona glomerulosa of the adrenal cortex

Question 16

What is the effect of Aldosterone on the kidneys?

Answer 16

Upregulated epithelial Na channels of DCT/CD so more Na (and therefore water) is reabsorbed.
Stimulates the excretion of K

Question 17

Where are Glucocorticoids secreted?

Answer 17

Zona fasiculata of the adrenal cortex

Question 18

Where are precursor androgens secreted?

Answer 18

Zona reticularis of the adrenal cortex

Absorbed by the ovaries or testes which convert into oestrogen or testosterone

Question 19

What does the medulla of the adrenal gland secrete?

Answer 19

Adrenaline
Noradrenaline
Small amounts of Dopamine

Question 20

What is the MOA of Osmotic Diuretics?

Answer 20

Freely filtered by the kidney and cause decreased water reabsorption
Decrease brain volume and decrease ICP
Used for increased ICP, glaucoma and rhabdomyolysis
Can cause nausea/vomiting, pulmonary oedema, decreased Na levels
(mannitol)