Renin -Angiotensin System (RAS)
Renin-Angiotensin aldosterone system that regulates blood pressure and water (fluid) balance.
It is center of controling blood pressure in the body.
Low renal blood flow or low blood pressure or law Na+ level
Tubules/ kidney renal blood flow pressure is low
Secrete renin by JG cells
Reach liver and excite to liver relaease
Angiotensin l
Reach in lung and convert (due to presence of ACE inhibitors)
Angiotensin ll ( angiotensin converting enzyme comming from lung)
Increased blood pressure (vasoconstriction; raised blood pressure)
(Start negative feedback mechanism here)
Go to kidney again and decrease the secretion of renin and maintain blood pressure normal.
Tubules (JG cell)
Decrease secretion of renin
Maintain normal Blood pressure
Angiotensin ll -- Vasoconstriction --- increase blood pressure --- -ve feed back mechanism start
Adrenal gland (adrenal cortex)
Aldosterone
Selective reabsorption of sodium and excretion of potassium
Due to reabsorption
Increase blood level of Na+
Blood pressure will be increase
(Start negative feedback mechanism here)
Go to adrenal cortex
Decrease the secretion of aldosterone
Bring blood pressure back to normal
1. Due to decreased renal blood flow or decreased blood pressure or decreased sodium level in kidney.
2. Renin will secreted in kidney
3. This secretion of renin will convert angiotensinogen (comming from liver and kidney) converted into angiotensin l.
4. Angiotensin l wiil be converted into Angiotensin ll
5. Due to formation of angiotensin ll vasoconstriction will increase blood pressure.
6. After vasoconstriction or after increase blood pressure, negative feed back mechanism is activated which will act in kidney and decrease the secretion of renin.
Onthe other hand,
1. Angiotensin ll will act on adrenal cortex and will cause secretion of aldosterone.
2. Secretion of aldosterone will lead to reabsorption of sodium and excretion of potassium from kidney tubules.
3. Due to reabsorption of sodium, blood sodium level will increase and ultimately will cause increase in blood pressure.
4. With the increasing blood pressure, negative feed back mechanism will be activated and it will act on adrenal cortex and reduce secretion of aldosterone.
5. Which will bring back blood pressure in normal.
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