Feature |
Extracellular Fluid (ECF) |
Intracellular Fluid (ICF) |
Location |
Outside the cells |
Inside the cells |
Volume |
~20% of total body weight |
~40% of total body weight |
Main Cation |
Sodium (Na+) |
Potassium (K+) |
Main Anion |
Chloride (Cl-) > Bicarbonate (HCO3) |
Phosphate (PO4) and Proteins |
pH |
~7.4 (slightly alkaline) |
~7.0 (neutral) |
Protein Content |
Low (except in plasma) |
High (inside the cell cytoplasm) |
Osmolality |
~290 mOsm/kg |
~290 mOsm/kg |
Subdivisions |
- Interstitial fluid (surrounds cells) - Plasma (intravascular fluid) |
Not subdivided |
Glucose |
High |
Low (utilized for energy) |