RAAS system

Question 1

Renin

Answer 1

• Enzyme from the kidney
• Converts angiotensinogen to Angiotensin I

Why do the kidneys release renin? If homeostasis of BP etc is needed

• Drop in renal blood flow/BP
• Fall in sodium concentration in renal tubules
• Sympathetic nervous system and prostacyclin

Question 2

Angiotensin II

Answer 2

• major player, very potent molecule cardiovascularly

• Causes vasoconstriction – blood vessels get smaller (AT1 rec)
• Causes release of aldosterone from adrenal cortex (AT1 rec)
• Vasoconstriction and release of aldosterone cause = increase in BP
• Acts on 2 different types of receptors (AT1 + AT2 receptors)

Question 3

Aldosterone

Answer 3

• Acts on the distal convoluted tubule + collecting duct in the nephron
• Increases the reabsorption (uptake) of sodium and water – pulls sodium/water back into the body
• Increases excretion of potassium – more potassium excreted in urine

Question 4

ACE inhibitors (Angiotensin Converting Enzyme Inhibitors) (-PRILs)

Answer 4

• Inhibit ACE (the enzyme that converts angiotensin I to II) + inhibit the breakdown of bradykinin
• Reduce vasoconstriction, sodium reabsorption, aldosterone release

side effect can cause cough

Question 5

ACE inhibitors indications

Answer 5

• HTN
• Chronic heart failure
• Prevent kidney failure in pts with high BP/diabetes
• Reduce risk of stroke
• Improve survival after MI
• Diabetic nephropathy

Question 6

Angiotensin II Receptor Antagonists

Answer 6

• Prevent angiontensin II from binding to type 1 angiotensin (AT1) receptors on blood vessels – they have the same result as ACE inhibitors
• Reduce vasoconstriction, sodium reabsorption, aldosterone release

Question 7

Angiotensin II Receptor Antagonists indications

Answer 7

• HTN
• Chronic heart failure
• Prevent kidney failure in pts with high BP/diabetes
• Reduce risk of stroke
• AF