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Old 04-15-2013
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Kidney How does Angiotensin Help Kidney Perfusion!

Guys i am little confused and need your help..

Actually we know that when renal. perfusion decreases the renin-angiotensin-aldosterone system is activated to increase renal perfusion BUT angiotensin cuz increase TPR which further reduces renal blood flow so how it is compensatory??
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Old 04-15-2013
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I think it's because angiotensin has a lesser constrictive effect on afferent and greater on efferent arteriole.

This automatically leads to increased hydrostatic pressure upstream which leads to increased urine output..... which is the ultimate aim of the kidney.

any other ideas??
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Old 04-15-2013
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Plz tell me that that does increase in TPR increase perfusion or decreae perfusion??? due to hemorrhage TPR is increased ,due to angiotensin2 TPR incresed ,due to decrease renal perfusion TPR increased.when standing from lying position TPR increased so itz function seems to increase perfusion.. BUT on another hand itz function seems to decrease perfusion as increasing sympathatic activty. cuz increase TPR which reduce blood supply to skin,kidney and GIT..
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Old 04-16-2013
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well... when you take hemorrhage... the body percieves it as a stressful situation.... the body is losing blood.... and the first thing it does is conserve the blood supply to it's major organs... The Brain.. The heart etc.....

so by decreasing the blood supply to the minor organs like kidney and skin... it conserves blood to be sent to major necessary organs...

That is the main reason for sympathetic action causing varied effects
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Old 04-16-2013
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Vinaya
is correct about the efferent
arteriole being more constricted
overall
resulting in a higher GFR.
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Old 04-17-2013
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Thanks vinaya and add.
Can u plz tell me that angiotensin is released in stress condition and it should decreaae gfr to increase blood volume but why it increases gfr?
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Old 04-17-2013
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Quote:
Originally Posted by medicalbiology View Post
Thanks vinaya and add.
Can u plz tell me that angiotensin is released in stress condition and it should decreaae gfr to increase blood volume but why it increases gfr?
angiotensin increases gfr to maintain renal perfusion ...at the same time renin increases aldosterone which reabsorbs Na and water in collecting tube to increase blood volume

correct if i'm wrong.
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