Interstitial fluid

Interstitial fluid or tissue fluid is a solution that bathes and surrounds the tissue cells of multicellular animals. It is the main component of the extracellular fluid, which also includes plasma and transcellular fluid. The interstitial fluid is found in the interstices - the spaces between cells (also known as the tissue spaces). On average, a person has about 10 litres (2.4 imperial gallons or ~2.9 US gal) of interstitial fluid (they make up 16% of the total body weight), providing the cells of the body with nutrients and a means of waste removal.

Production and removal

Plasma and interstitial fluid are very similar. This similarity exists because water, ions, and small solutes are continuously exchanged between plasma and interstitial fluids across the walls of capillaries. Plasma, the major component in blood, communicates freely with interstitial fluid through pores and intercellular clefts in capillary endothelium.

Formation

Hydrostatic pressure is generated by the systolic force of the heart. It pushes water out of the capillaries.