Renin-Angiotensin-Aldosterone System (RAAS) NCLEX Review

Renin-angiotensin-aldosterone system (RAAS) review for nursing students!

Why do you need to know about the RAAS? This system is very important in managing our blood pressure, especially when the blood pressure falls too low. In addition, nurses should know how the renin-angiotensin-aldosterone system works so they can understand how certain cardiac medications (like ACE inhibitors) work to lower the blood pressure in the body.

Don’t forget to take the RAAS quiz and to watch the renin-angiotensin-aldosterone lecture after reviewing these notes.

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RAAS Nursing Lecture

Renin-Angiotensin-Aldosterone System (RAAS) Nursing Review

The role of the renin-angiotensin-aldosterone system (RAAS)? To increase the blood pressure when it becomes too low by activating Angiotensin II.

Angiotensin II will cause MAJOR vasoconstriction and help increase the blood volume by causing the kidneys to conserve sodium and water and triggers the release of aldosterone and ADH (antidiuretic hormone).

How the RAAS Works (step-by-step):

1. Blood pressure drops too low ->
2. Sympathetic Nervous System (fight or flight system) is stimulated and sends nerve impulses to Juxtaglomerular Cells in the kidneys to release RENIN ->
3. With RENIN present in the circulation it will activate a substance in the liver called ANGIOTENSINOGEN. This causes angiotensinogen to turn into…
4. ANGIOTENSIN I: With this substance present in the vessels it will cause ACE to become involved…
5. ACE stands for Angiotensin-Converting Enzyme. ACE (just as it name says) will convert Angiotensin I into…
6. ANGIOTENSIN II: Now the end result of the RAAS has occurred…it just activated Angiotensin II, which will cause:
   1. Vasoconstriction: both venous and arterial vessels will constrict. This will INCREASE systemic vascular resistance (SVR) and blood pressure.
   2. Increase Blood Volume: How???
      1. Kidneys will keep water and sodium
      2. Adrenal cortex gland will be triggered by angiotensin II to release aldosterone. Aldosterone will also cause the kidneys to keep sodium and water and excrete potassium.
      3. Pituitary gland will be triggered by angiotensin II to released ADH (antidiuretic hormone. ADH will cause the kidneys to keep water.

7. End Result: increased blood pressure

Note: How would ACE Inhibitors work to decrease the blood pressure? It would inhibit ACE from converting angiotensin I to angiotensin II. Therefore, step 5, as demonstrated above would not happen.

References