USMLE Forum - Largest USMLE Community

given these data ,ehat is the net filtration pressure at the glomerulus .
glomerular hydrostatic pressure =44mm hg
bowmans capsule hydrostatic pressure =9mmhg
osmotic pressure of plama =28mm of hg
osmotic pressure of tubular fluid =0
a.-5mm of hg.
b.7mm of hg
c.25mm of hg
d.63mm of hg
e.81mm 0f hg

Ans: BB

correct .B is the answer .filtration pressure is the difference between the forces pushing fluid out and forces pulling fluid back into the glomerulus .Pushing forces are the hydrostatic pressure of the glomerulus (44 mm of hg )and the osmotic pressure of tubular fluid (0).so the total pressure forcing fluid from the glomerulus into the tubular fluid is 44mm of hg .

The forces pulling the fluid back are the hydrostatic pressure of the bowmans capsule (9mm of hg )and the osmotic pressure of the plasma (28mm of hg ).So the total pressure pushing the fluid back into the glomerulus is 9+28=37mm of hg.So the difference between the forces favouring filtration and tose opposing it is 44-37=7 mm of hg .