RAAS System Flashcards
the RAAS system is a physiologic regulator of 2 things
total peripheral resistance and blood volume
renin cleaves ____ to ____
angiotensinogen to ang I, if no renin then Angiotensinogen will be degraded
How many AA does ang 1 and ang 2 have
Ang 1 has 10 and Ang 2 has 8
Angiotensin 2 affects what 4 things after binding to the AT1 receptor
- adrenal (medullary thick ascending lib of henle, collecting duct) - increases NaCl absorption
- renal proximal tubule (increased NaCl absorption)
- Renal Efferent arterioles (vasoconstriction maintains GFR)
- Hypothalamus (thirst, increased ADH secretion)
what stimulates RAAS
decreased blood volume, Na+ depletion, increased sympathetic outflow, leads to the release of renin (rate limiting step) to start the RAAS cascade
Role of ACE
expressed in the lung. inactivates bradykinin (vasodilator), converts Ang 1 to Ang 2
what releases renin
JG cells
what 3 things regulate renin release
- intra macula densa pathway (NaCl concentration low inc renin release)
- intrarenal baroreceptor pathway ( high pressure dec renin release and visa versa)
- beta adrenergic pathway (SNA system- B1 receptor, NE release)
short loop negative feedback
releases renin - inc ang 2 - goes to AT1 transporter, once body sees response it inhibits renin release
long loop negative feedback (2)
- increased BP- increased pressure at preglomerular vessels - dec renin
- increased BP- activation of baroreflex sytem decreased sympathetic tone - decreased NE release - decreased renin release (inc parasympathetic)
diuretics and vasodilators affect on renin
decrease blood volume and decrease arterial pressure - this increases renin release
loop diuretics affect on renin
decrease NaCl reabsorption - increases renin release
NSAIDS affect on renin release
decrease PG synthesis (more pressure) - decrease renin release (PG usually blocks reabsorption of Na+)
Beta Blockers affect on renin release
decrease activation of beta 1 receptors on JG cells- decreases the renin release
ang II effect on the kidney
intrarenal blood-pressure constriction (increases GFR, GFR plateaus then decreases ) renal tubules (increases Na+ and H2O reabsorption) - this increases Na+ and H2O retention
ang II effect on the adrenal gland
cortex - increases aldosterone (Na+ reabsorption)
ang II effect on the vascular smooth muscle
vasoconstriction, increase TPR, increase arteriolar resistance, increase cardiac output
ang II effect on the CNS
increase ADH (inc H2O reabsorption), increase thirst (inc H2O ingestion)
ang II effect on the myocardium
increase contractility, hypertrophy, collagenase, increase wall thickness, remodeling of the heart can block blood flow out of the ventricle
what 3 things do drugs targeting the RAAS cascade do
- decrease vascular constriction
- decrease aldosterone secretion
- decrease ADH release
Bradykinin
vasodilator and is inhibited by ACE, causes a dry cough, activates nitric oxide, increased with an ace inhibitor
aldosterone effects
AT1 activates, Na+ and H2O retention and Mg+ and K+ loss
what 3 drugs effect the RAAS cascade
- ACE inhibitors
- AT1 blockers
- Renin inhibitors
- Aldosterone receptor antagonists
where is the ACE site of cleavage on the
Phe - His