Physiology

Question 1

Glomerulus

Answer 1

Endothelium
Basement membrane
Epithelium

Question 2

Filtration

Answer 2

Receive 25% of CO
20% of blood volume is filtered

GBM is –vely charged → retention of anionic proteins

Question 3

PCT

Answer 3

Reabsorption of filtrate:
70% - Na+ reabsorption
100% reabsorption of amino acids, glucose, cations

Bicarbonate reabsorbed using carbonic anhydrase

Question 4

Thick Ascending Limb

Answer 4

Creates osmotic gradient
NKCC2
20% of Na reabsorption

Question 5

DCT

Answer 5

pH and Ca reabsorption:

• NaCl
• Na reabsorption
• Ca2+ reabsorption under control of PTH

Question 6

Medullary Collecting duct

Answer 6

pH and K regulation:
Na reabsorption coupled to K or H excretion

Basolateral aldosterone-sensitive Na/K pump

Question 7

Cortical CD

Answer 7

Regulation of water reabsorption

Aquaporin 2 - controlled by ADH

Question 8

Endocrine function of kidney

Answer 8

Secretion of renin by juxtaglomerular apparatus

EPO synthesis

Activates vitamin D

Question 9

Carbonic Anhydrase Inhibitors (acetazolamide)

Answer 9

Inhibits carbonic anhydrase in PCT

Effect: ↓ HCO3 reabsorption → ↑ Na secretion

Use: glaucoma

SE: drowsiness, renal stones, metabolic acidosis

Question 10

Loop Diuretics

Answer 10

Examples: furosemide, bumetanide

Inhibit NKCC2 symporter in thick ascending limb

Effect: Excretion of Na+, Cl-, K+ and Ca2+

Use: Mx of oedema – CCF, nephrotic syndrome,
hypercalcaemia

SE:
Hypokalaemic
Met alkalosis
Ototoxic
Hypovolaemia

Question 11

Thiazide Diuretics (bendroflumethazide)

Answer 11

Inhibit NaCl co-transporter in DCT

Effect: NaCl excretion, ↑ Ca reabsorption

Use: HTN, ↓ renal stones, mild oedema

SE:
↓K
Hyperglycaemia
↑ urate (CI in gout)

Question 12

K+ Sparing Diuretics

Answer 12

Spironolactone

Amiloride

Question 13

Spironolactone

Answer 13

Aldosterone antagonist

Effect: ↑ Na excretion, ↓K and H excretion

Use:

• used with loop or thiazide diuretics to control K loss
• Long-term benefits in aldosteronsim

SE: ↑K, anti-androgenic (e.g. gynaecomastia)

Question 14

Amiloride

Answer 14

Blocks DCT/CD luminal Na channel

Effect: ↑ Na excretion, ↓K and H excretion

Use:
- used with loop or thiazide diuretics to control K loss

SE: ↑K

Question 15

Mannitol - osmotic diuretic

Answer 15

Freely filtered and poorly reabsorbed

Effect: ↓ brain volume and ↓ ICP

Use: glaucoma, ↑ICP, rhabdomyolysis

SE: ↓Na, pulmonary oedema, n/v