Extracellular fluid accounts for about one third of
body fluids (Tortora and Derrickson 2009a) and
is further separated into two compartments, the
interstitial fluid and plasma contained within the
blood vessels. The cells are surrounded by interstitial
fluid, which accounts for 80% of extracellular
fluid. However, interstitial fluid also includes
lymph, cerebrospinal fluid, synovial fluid, aqueous
humor and vitreous body, and pleural, pericardial
and peritoneal fluids (Tortora and Derrickson
2009b).