Patho Patho #8

Question

What is the result of initiation of activation of the renin-angiotensin-aldosterone system?

Answers

  1. Na+ and fluid excretion and hypotension.
    • Rationale:

      This answer is not correct because the end result of RAAS is Na+ and fluid retention leading to increased blood pressure as opposed to hypotension.

  2. Increased diuresis, Na+ excretion and vasodilation.
    • Rationale:

      This answer choice is not correct as RAAS causes vasoconstriction, Na+ retention, and fluid retention with the intent to increase blood pressure and renal perfusion.

  3. Increased Na+, K+, and Ca+ stored within the cells.
    • Rationale:

      This answer choice is not correct as RAAS does not increase cellular concentration of Na+, K+, or Ca+. RAAS causes vasoconstriction, and Na+ and fluid retention within the vessels.

  4. Retention of fluid and Na+ and vasoconstriction.
    • Rationale:

      This answer is correct as the RAA system is activated by the release of renin in response to decreased renal perfusion. The end result of these actions are vasoconstriction and Na+ and fluid retention.

Overview

When renal perfusion is decreased the kidneys release renin in response. Renin converts to angiotensin I and then II and finally aldosterone. The end result is increased blood pressure which improves perfusion to the kidneys.

Explanation

Learning Outcomes

The renin-angiotensin-aldosterone system (RAAS) is activated when renal perfusion is decreased due to hypovolemia or cardiac output. Angiotensin II causes peripheral vasoconstriction and aldosterone leads to Na+ and fluid retention. The end result of RAAS is increased volume and afterload which increases blood pressure and perfusion.

Test Taking Tip

Look at each answer choice carefully. Two answers refer to an increase in cellular Na+ retention or excretion of Na+. Most often, if two answers are very similar to each other they may be ruled out as possible answers through process of elimination.

Video Rationale