Questions: UNIT 3 - CHALLENGE 3.3: The Urinar 6- Microscopic Anatomy of the Kidney LEARNING OBJECTIVE: Define the structure and function of the nephron. Which of the following is a potent vasoconstrictor and stimulates the secretion of aldosterone? a.) Renin b.) Angiotensin I c) Angiotensin II d) Angiotensinogen SUBMIT MY ANSWER Report an issue with this question

The answer is c) Angiotensin II.

Explanation for each option:

a) Renin: This is an enzyme secreted by the kidneys that plays a crucial role in the renin-angiotensin-aldosterone system (RAAS). It initiates the conversion of angiotensinogen to angiotensin I but is not itself a vasoconstrictor or directly involved in aldosterone secretion.

b) Angiotensin I: This is a precursor to angiotensin II and is formed by the action of renin on angiotensinogen. It has little direct biological activity and does not act as a potent vasoconstrictor or stimulate aldosterone secretion.

c) Angiotensin II: This is the correct answer. Angiotensin II is a potent vasoconstrictor and plays a key role in increasing blood pressure. It also stimulates the secretion of aldosterone from the adrenal cortex, which helps regulate blood pressure and fluid balance.

d) Angiotensinogen: This is a precursor protein produced by the liver. It is converted to angiotensin I by renin but does not have vasoconstrictor properties or directly stimulate aldosterone secretion.

In summary, angiotensin II is the active component in the RAAS that causes vasoconstriction and stimulates aldosterone secretion.