Renal Physiology and Diuretics Flashcards
Describe the glomerulus of the kidney?
- Epithelial pouch invaginated by capillary tuft
- Semi-permeable filter
- Endothelium
- BM
- Epithelium
- Mesangial cells are specialised smooth muscle cells that support the glomerulus and regulate blood flow/GFR
Describe the relevance of Na+ reabsorption?
- Main factor for determining extracellular volume
- Reduced BP and NaCl at macula densa (DCT)
- Renin release
- Aldosterone release
- More Na/K pumps
Describe the relevance of water reabsorption?
- Determines extracellular fluid osmolality
- Raised osmolality / hypotension
- => ADH release
Describe the PCT of the nephron?
- Reabsorption of filtrate
- 70% of total Na+ reabsorption
- Reabsorption of amino acids, glucose, cations
- Bicarbonate reabosrbed using carbonic anhydrase
Describe the Thick ascending limb of the nephron?
- Creation of osmolality gradient
- 20% of Na reabsorption
- Na/K/2Cl triple symporter
Describe the DCT of the nephron?
- pH and Ca2+ reabsorption
- 5% of Na reabsorption
- Apical NaCl co-transporter
- Ca2+ reabsorption under control of PTH
Describe the medullar collecting duct of the nephron?
- pH and K+ regulation
- Na+ reabsorption coupled to K or H excretion
- Basolateral aldosterone-sensitive Na/K pump
Describe the cortical collecting duct of the nephron?
- Regulation of water reabsorption
- Controled by aquaporin-2 channels
Describe the endocrine function of the kidney?
- Secretion of renin by juxtaglomerular apparatus
- EPO synthesis
- 1a-hydroxylation of vitamin D (controlled by PTH)
MOA of Carbonic anhydrase inhibitors?
- Inhibit carbonic anhydrase in the PCT
- Reduced bicarbonate reabsorption
- Causes small increase in Na+ excretion
Example of a Carbonic anhydrase inhibitor?
Acetazolamide
Indication for Carbonic anhydrase inhibitor?
Glaucoma
SEs of Carbonic anhydrase inhibitor?
- Drowsiness
- Renal stones
- Metabolic acidosis
MOA of loop diuretics?
- Inhibit Na/K/2Cl symporter in thick ascending limb
- Massive NaCl excretion
- Ca2+ and K+ excretion
Examples of loop diuretics?
- Furosemide
- Bumetanide
Indications for loop diuretics?
- Treatment of oedema
- CCF
- Nephrotic syndrome
- Hypercalcaemia
SEs of loop diuretics?
- Hypoakalaemic metabolic alkalosis
- Hypovolaemia
MOA of thiazide diuretics?
- Inhibit NaCl co-transporters in DCT
- Moderate NaCl excretion
- Increased calcium reabsorption
Example of thiazide diuretics?
Bendroflumethiazide
Indication for thiazide diuretics?
- HTN
- Reduce renal stones
- Mild oedema
SEs of thiazide diuretics?
- Hypokalaemia
- Hyperglcyaemia
- Increased urate (contraindicated in gout)
MOA of K+-sparing diuretics?
- Spiro: aldosterone antagonist
- Amiloride: blocks DCT/collecting duct luminal Na+ channel
- Increased Na+ excretion, erduced K+ and H+ excretion
Examples of K+-sparing diuretics?
- Spironolactone
- Epelerone
- Amiloride
Indications for K+-sparing diuretics?
- Used with loop/thiazide diuretics to control K+ loss
- Spironolactone has long term benefits in aldosteronism
SEs of K+-sparing diuretics?
- Hyperkalaemia
- Anti-androgenic (Eg gynaecomastia)
MOA of osmotic diuretics?
- Freely filtered and poorly reabsorbed
- Reduced brain volume and ICP
Example of an osmotic diuretic?
Mannitol
Indications for mannitol?
- Glaucoma
- Raised ICP
- Rhabdomyolysis
Side effects of osmotic diuretics?
- Hyponatraemia
- Pulmonary oedema
- N/V
