The net pressure gradient that causes the fluid to filter out of the glomeruli into the capsule is -

Options

A. 50mm Hg
B. 75mm Hg
C. 20mm Hg
D. 30mm Hg

Answer

B

Explanation

Fluid is forced out of the glomerular capillaries into the Bowman’s capsule by the high pressure of the blood in the glomerular capillaries.
This pressure is about 70 mm. Hg in man. The fluid tends to move in the reverse direction due to (i) the osmotic pressure of plasma proteins in the glomerular capillaries, and (ii) hydrostatic pressure of the fluid in the urinary tubule. These pressures in man are about 30 mm. Hg. and 20 mm. Hg. respectively. The net force moving the fluid from the glomerular capillaries, called the filtration pressure, is 70 – (30 + 20) or 20 mm. Hg.