The most obvious difference between these two fluids is that one is inside of the cell and the other is outside of the cell. Extracellular fluid accounts for about 1/3 of the fluid in the human body and has more ionic components than intracellular fluid. The two main types of extracellular fluid are blood plasma and interstitial fluids. Intracellular fluid, also called cytosol, makes up the other 2/3 of the fluids in the human body. This fluid contains more amino acids and proteins than extracellular fluid.