Question

Effective filtration pressure in the glomerulus in kidney of man is about

• A. + 75 mm Hg
• B. + 10 mm Hg
• C. + 35 mm Hg
• D. + 50 mm Hg

Answer 1

The correct option is B + 10 mm Hg

Effective filtration pressure (EFP) refers to the net driving forces for water and solute transport across the glomerular membrane. EFP is a function of three variables
1) Glomerular Hydrostatic Pressure - It is blood pressure in a glomerular capillaries due to narrower efferent arteriole and is the chief determinant of EFR. Its value is 60 to 75 mm Hg
2) Capsular Hydrostatic Pressure - the hydrostatic pressure driving fluid into the Bowman's capsule. Its value is 10 to 20 mm Hg
3) Blood Colloid Osmotic Pressure - It is osmotic pressure created in the blood of glomerular capillaries due to plasma proteins. Its value is 30 to 32 mm Hg.
Using these variables, the EFP is expressed as:
EFP = Pcap (COPcap+ PBow)
EFP ranges from 10 to 25 mm Hg.