Originally Posted by drnirajmavani
i got a que wrong on UWSA2 by using this same logic.... the que was abt reducing the diameter of renal art by 75% i.e. stenosis ---> resistance increase by 256 times ----> this decreases the RBF..this should also decrease the GFR and FF should remain constant ... but i got this wrong nd UWSA explanation said the FF INCREASES
>... i dnt kno if i m missing out some concept in dis..
The uworld explanation says that "renal afferent arteriolar dilation and constriction allow the glomerular capillary hydrostatic pressure and GFR to remain stable when arterial blood pressure is maintained between 80 and 180 mmHg.Below 80 mmHg ,GFR and capillary hydrostatic pressure will decrease.A decrease in renal artery radius of 75% may cause such a drastic decrease in renal arterial pressure"..
here i feel some contradiction in UW explanation..and the answer..or may be because I didnt understand it.
Also the increase in FF is due to decrease in RBF due to severe stenosis of renal artery..here UW does not explain the affect of GFR..