and we’re back! with BRAND SPANKIN' NEW tangents!
to snoo-finity ... and beyond!
NBME 24 Answers
A 75-year-old man with a 10-year history of ...
Hydrostatic pressure in Bowman space
Between the glomerulus and Bowman's space there is a hydrostatic pressure gradient.
This gradient is normally the result of a LARGE glomerular hydrostatic pressure and a LOW pressure in Bowman's space which normally favors filtration.
Diagram here: http://physiologyplus.com/wp-content/uploads/2017/08/Glomerular-Filtration.png
In the case of post-renal obstruction, hydrostatic pressure behind the blockade will rise and urine will reflux into the capsular space and renal tubules (while glomerular hydrostatic pressure is unaffected) effectively decreasing the pressure gradient which reduces the filtration rate.
the key here is the term hydronephrotic kidney. anytime there is that, there is a post renal obstruction of some sort. The fact that he has progressive renal failure just contributes to the idea that his kidneys have seen damage before and are not able to withstand the pressure from the back up as well. I got tripped up on this. The important thing to note is that Hydronephrosis and dilation = back up = increased in volume pressure (hydrostatic)