USMLE Forum Archives - USMLE Step 1 - role of angiotensin II in changing GFR,
role of angiotensin II in changing GFR,
drspleen - 03-17-11 18:26
A scientist seeks to evaluate the role of angiotensin II in changing GFR, RPF and FF. In the presence of angiotensin II, how will these measurements change?
* A. GFR decreases, RPF increase, FF normal
* B. GFR increase, RPF decrease, FF increase
* C. GFR normal, RPF normal, FF increase
* D. GFR decrease, RPF no change, FF decrease
* E. GFR decrease, RPF decrease, FF normal
drspleen - 03-17-11 18:26
A scientist seeks to evaluate the role of angiotensin II in changing GFR, RPF and FF. In the presence of angiotensin II, how will these measurements change?
* A. GFR decreases, RPF increase, FF normal
* B. GFR increase, RPF decrease, FF increase
* C. GFR normal, RPF normal, FF increase
* D. GFR decrease, RPF no change, FF decrease
* E. GFR decrease, RPF decrease, FF normal
The correct answer and explanation will be available after you answer.
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#3
Re: role of angiotensin II in changing G babbu5508 - 03-18-11 19:02 My answer is: b.
andiotensin II specifically constricts efferent arteriole and thereby causes increased FF, but vasoconstriction causes decreased RPF
#4
Re: role of angiotensin II in changing G sudha2015 - 03-19-11 10:25 A scientist seeks to evaluate the role of angiotensin II in changing GFR, RPF and FF. In the presence of angiotensin II, how will these measurements change
b
#5
Re: role of angiotensin II in changing G
drspleen - 03-21-11 18:38 The powerful vasoconstrictor angiotensin II preferentially constricts efferent arterioles. This constriction will increase GFR but will decrease RPF. Since FF = GFR/RPF, FF will also increase. Patients taking ACE inhibitors or angiotensin II receptor blockers will abolish this effect and will have a decreased GFR.
#7
Re: role of angiotensin II in changing G stardust - 03-29-12 18:06 I think C is the correct answer
..reason being that angiotensin 2 raises renal resistance without any major changes in the GFR
therefore...GFR stays normal, RPF Decreases and FF increases.
#8
Re: role of angiotensin II in changing G stardust - 03-29-12 18:10 My answer is: c.
Angiotensin 2 increases renal resistance and decreases RPF WITHOUT any significant change to GFR .
So GFR:same
RPF: Decrease
FF: Increase
#9
Re: role of angiotensin II in changing G stardust - 03-29-12 18:26 O sorry I read thT all wrong.... B makes most sense.... I read C all wrong :p my bad :)
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