RAAS Flashcards
What triggers renin release from juxtaglomerular cells?
a) High BP
b) Low NaCl delivery to macula densa
c) Increased GFR
d) High K+ in plasma
b) Low NaCl delivery to macula densa
Explanation: JG cells release renin in response to decreased renal perfusion pressure, low NaCl sensed by the macula densa, or sympathetic stimulation.
What is the function of renin in the RAAS pathway?
a) Converts angiotensin I to angiotensin II
b) Converts angiotensinogen to angiotensin I
c) Stimulates aldosterone secretion
d) Promotes Na+ secretion
b) Converts angiotensinogen to angiotensin I
Explanation: Renin is an enzyme that cleaves angiotensinogen (from the liver) into angiotensin I, the first step in the RAAS cascade.
What are the main effects of angiotensin II?
a) Vasodilation and ADH inhibition
b) Inhibition of thirst
c) Increased GFR and Na+ excretion
d) Vasoconstriction and aldosterone release
d) Vasoconstriction and aldosterone release
Explanation: Angiotensin II constricts blood vessels (especially efferent arterioles), stimulates aldosterone release, promotes thirst, and increases ADH secretion.
How does angiotensin II affect the kidney to raise GFR?
a) Constricts both arterioles, more strongly efferent
b) Dilates afferent arteriole
c) Inhibits renin release
d) Increases proximal tubule Na+ excretion
a) Constricts both arterioles, more strongly efferent
Explanation: Ang II preferentially constricts the efferent arteriole, helping maintain GFR despite low systemic pressure.
Which hormone in the RAAS pathway acts directly on the nephron to retain sodium?
a) ADH
b) Angiotensin I
c) Aldosterone
d) Renin
c) Aldosterone
Explanation: Aldosterone acts on the distal tubule and collecting duct to increase sodium reabsorption and potassium secretion.
