The net pressure gradient that causes the fluid to filter out of...

Kidneys help in the formation of urine, from the blood flowing through glomerular capillaries. About $20 \%$ of plasma fluid filters out into the Bowman's capsule through a thin glomerular-capsular membrane due to a net or effective filtration of about 10 to $15 \mathrm{~mm} \mathrm{Hg}$. Related Theory Urine is a waste byproduct formed from excess water and metabolic waste molecules during the process of renal system filtration. The primary function of the renal system is to regulate blood volume and plasma osmolarity, and waste removal via urine is essentially a convenient way that the body performs many functions using one process. Urine formation occurs during three processes: Filtration, Reabsorption and Secretion. (Ref. to Fig. 27.4)