Which equation is most accurate?

Question

Which equation is most accurate?

a) Extracellular fluid volume - interstitial fluid volume = circulatory fluid volume

b) Extracellular fluid volume + interstitial fluid volume = whole body fluid volume

c) Intracellular fluid volume + interstitial fluid volume = extracellular fluid volume

d) Plasma volume + intracellular fluid volume = extracellular fluid volume

Answer 1

The body's fluid is divided into two main compartments:

1. Intracellular fluid volume ('intra' means 'within' - so intracellular is within the cell)
2. Extracellular fluid volume (i.e., fluid outside of the cell)

Extracellular fluid volume is also divided into two main compartments:

a. Plasma volume (fluid within the circulatory system)

b. Interstitial fluid volume ('inter' means between; this is the fluid that exists between cells, within tissues)