The renin-angiotensin-aldosterone system (RAAS) is the system of hormones, proteins, enzymes and reactions that regulate your blood pressure and blood volume on a long-term basis. It regulates your blood pressure by increasing sodium (salt) reabsorption, water reabsorption (retention) and vascular tone (the degree to which your blood vessels constrict, or narrow).

1. RAAS
(Renin-Angiotensin-Aldosterone system)
BY:SURAJ SINGH
BATCH:2022
PHYSIOLOGY SEMINAR

2. RAAS is a hormone system within the body that is essential
for the regulation of body fluid balance
it helps in long term BP regulation
Introduction

3. EXTRA GLOMERULAR
MESANGIAL CELL

4. Mechanism of action

5. Stimulus
Decrease in Blood pressure
Eg.
a) Haemorrhage
b) Diuretic administration
c) Dehydration
d) e)Hypotension
f)Salt depletion

6. This is a glycoprotein synthesized in liver .
Concentration increased by following hormones:-
1)Glucocorticoids
2)Thyroid hormones
3)Estrogen
4)Angiotensin II
Angiotensinogen
Secretion

7. Renin
*It is a glycoprotein.
*Secreted by Juxtaglomerular Apparatus(JGA) into
afferent arteriole.
*Stored in granules of JG Cells.

8. REGULATION OF RENIN
• An intra-renal baroreceptor mechanism that causes renin secretion to
decrease when arteriolar pressure at the level of the JG cells increases
and to increase the level of renin when arteriolar pressure at this level
falls.
• Macula densa are sensitive to the concentration of Na+ in arteriolar
blood,
a decrease in Na+ level cause increase in the level of renin

9. Angiotensin-converting Enzyme
Angiotensin-converting Enzyme is a carboxypeptidase.
it acts on angiotensin I to convert it to angiotensin II
ACE Synthesized in blood vessels of lungs.
Hence ,major conversion of angiotensin I to angiotensin II occurs in
the lungs.

10. FUNCTIONS OF ANGIOTENSIN II
Angiotensin II
act on
Blood vessels
Adrenal cortex
Posterior pituitary

11. i. Generalised vasoconstriction
ii. Secretion and synthesis of aldosterone from adrenal cortex  increase Na+
reabsorption.
iii. Stimulate ADH Secretion from posterior pituitary  increase solute free water
reabsorption.
iv. Stimulate thirst mechanism  water intake increase
v. Therefore angiotensin II plays a key role in the body response to hypovolemia.
FUNCTIONS OF ANGIOTENSIN II