GFR is increased by all except?
(A) Increased renal blood flow (B) Efferent aeriole constriction (C) Renal stone in ureter (D) Decreased oncotic pressure
(C) Increased blood flow to glomerular capillaries causes increased capillary hydrostatic pressure causing increased GFR. The efferent aeriole constriction also causes increased capillary hydrostatic pressure causing increased GFR. Plasma colloid oncotic pressure is the force that opposes the filtration; when it is decreased, GFR increased. In case of nephrolithiasis or renal stone, there will be decreased flow of tubular fluid which causes fluid accumulation in Bowman's capsule leading to increased hydrostatic pressure in Bowman's capsule which opposes filtration causing decreased GFR Net filtration pressure = PG -PB - pG PG: glomerular hydrostatic pressure PB: hydrostatic pressure in Bowman's capsule PG: Colloid osmotic pressure of glomerular capillary plasma proteins GFR = KFX net filtration pressure KF = capillary filtration coefficient