What Students Need To Know About The Urinary System: Filtration and Fluid Balance.

Filtration is the transport of water and dissolved materials through a membrane from an area of higher pressure to an area of lower pressure. It operates somewhat like a sieve. Filtration requires mechanical pressure. Liquids and solutes are passed through holes in a membrane. The size of the holes and the differences in pressures (mechanical force) on each side determine the amount of filtration. Filtration can be thought of as a “pushing pressure” because it pushes water and solutes through a membrane from a higher pressure area to a lower pressure area. The three main compartments are • Fluid within cells • Fluid in the space around cells • Blood To function normally, the body must keep fluid levels from varying too much in these areas. Some minerals—especially the macrominerals (minerals the body needs in relatively large amounts)—are important as electrolytes. Electrolytes are minerals that carry an electric charge when they are dissolved in a liquid such as blood. The blood electrolyte