The process of ultra filtration occurs in the Malpighian corpuscles of the nephrons. The glomerulus of a Malpighian corpuscles is a network of several parallel capillaries. From the blood flowing through glomerular capillaries, about 20% of plasma fluid filters out into the Bowman's capsule through thin glomerular-capsular membrane due to a net or Effective Filtration Pressure (EFP) of about 10 to 15mmHg.