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Q. can anybody explain;
1. why constriction of ureter causes no change in RPF? shouldn't it decrease?
2. How efferent arteriole constriction decreases RPF?

I am having difficulty understanding RPF in relation to other parameters. Pls help with the concept of RPF. I googled but didn't find satisfactory explanation. (From FA- renal physiology)
 

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Q. can anybody explain;
1. why constriction of ureter causes no change in RPF? shouldn't it decrease?
2. How efferent arteriole constriction decreases RPF?

I am having difficulty understanding RPF in relation to other parameters. Pls help with the concept of RPF. I googled but didn't find satisfactory explanation. (From FA- renal physiology)
1. Constriction of ureter will cause a decrease in filtration but blood flow will remain the same. It just will not get out into the Bowmans space.

2. When the efferent arteriole constricts there is an increased resistance so everything "behind" the constriction will back up. It will increase the glomerular capillary pressure and decrease the pressure gradient between the renal arteries and glomerular capillaries. Just the different ways of saying the same thing.

Renal plasma flow is how much plasma goes through the kidney per unit time. Effective renal plasma flow is how much plasma goes through the whole filtration, secretion, reabsorption thing. Because not all of the blood in renal arteries is going to participate in the exchange that happens in the kidneys. PAH gives eRPF which will underestimate true renal plasma flow. Anytime there is increased resistance anywhere in the vasculature of the kidneys renal plasma flow will decrease. Glomerular filtration is entirely dependent on the Starling forces. So when the ureters get constricted (or obstructed), at least theoretically, interstitial hydrostatic pressure will go up and decrease filtration (coming from the Starling equation).
 
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