All about Renin-Angiotensin-Aldosteron-System

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The renin-angiotensin system plays an important role in regulating blood volume, arterial pressure, and cardiac and vascular function. While the pathways for the renin-angiotensin system have been found in a number of tissues, the most important site for renin release is the kidney. Sympathetic stimulation (acting via b1-adrenoceptors), renal artery hypotension, and decreased sodium delivery to the distal tubules stimulate the release of renin by the kidney. Renin is an enzyme that acts upon a circulating substrate, angiotensinogen, that undergoes proteolytic cleavage to from the decapeptide angiotensin I. Vascular endothelium, particularly in the lungs, has an enzyme, angiotensin converting enzyme (ACE), that cleaves off two amino acids to form the octapeptide, angiotensin II (AII).

http://www.oucom.ohiou.edu/CVPhysiology/BP015_RAS.gif

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This is a great site talking about Renin-Angiotensin-Aldosterone System

http://www.jraas.com/searchresults.asp?SearchTerms=Renin-Angiotensin-Aldosterone+System+

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It has been appreciated for some time that there is a link between the kidney's sodium balance and blood pressure. While some aspects of this complex relationship are now known, the extent to which the system serves a physical purpose and the frequency with which its breakdown is responsible for disease remain uncertain.

The kidney produces an enzyme called renin, which is essential for the production of another substance called angiotensin, which in turn constricts small arteries and arterioles.

Because the blood vessels of the kidney are highly sensitive to angiotensin, the latter can also act as an antidiuretic.A decrease in kidney blood flow (say, because of contraction (narrowing) of the arteries of the kidney) liberates renin from the kidney.

This enzyme is responsible for the appearance of angiotensin, which acts upon the adrenal cortex and increases the release of aldosterone.

This leads to sodium retention by the kidney. If sodium is retained, then so is water, and this in turn leads to a rise in blood volume. The blood pressure also rises because of an increased heart output.

To what extent an upset of these sequences is responsible for the raised blood pressure so frequently found in middle-aged and elderly people is not known.

http://www.tiscali.co.uk/reference/encyclopaedia/familyhealth/q_a/pages/1200.html

[H@SSOOM]

thanx alot my dear


let s finish anatomy periodic exam


then we ll consider about physiology
:LL:

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i hope that this topic will helpful in the research which Dr.Amer wants on sunday





Good Night

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[Dr.zero]

Hi ..

:12:

good work..
keep on my brother..
i'm sure that all of the 2nd year students
appreciate ur efforts.

Thanx..Cardiac arrest

may ALLAH bless all of u..


Have a nice studying with Physiology..

:o:


c u later..