Question

Explain the RAAS by listing (and briefly describing) several steps that occur in this process. What is the final outcome? What do ACE Inhibitors do?

Answer 1

Answer

RAAS is renin angiotensin aldosterone system

• RAAS is the mechanism to increase the blood pressure when the blood pressure levels decline below normal.
• When a decrease in blood pressure is detected, juxtaglomerular cells in kidneys release renin.
• Renin acts on angiotensinogen and convets it into angiotensin -I. Angiotensinogen is released from liver.
• Lungs release an enzyme called, ACE (Angiotensin converting enzyme). ACE acts on angiotensin-I and convets it into angiotensin -II.
• Angiotensin-II has several effects :
  1. It acts on blood vessels and cause vasoconstriction
  2. It stimulates release of aldosterone from adrenal cortex. Aldosterone increase sodium reabsorption from nephrone.
  3. It also stimulate release of ADH from posterior pituitary to increase water reabsorption.
• The collective effect of these events causes blood pressure to rise.

- The final outcome is : The blood pressure is increased and homeostasis is acheived.

- Role of ACE inhibitors

• ACE inhibitors are a class of anti-hypertensive agents.
• ACE inhibitors tend to block angiotensin converting enzyme and prevent conversion of angiotensin-I into angiotensin-II.
• ACE inhibitors are provided to patients with hypertension. It helps to keep the blood pressure in normal range.