Final answer:
The osmolarity of extracellular fluid is typically close to 285-295 mOsm/L, matching that of blood plasma, while intracellular fluid has a similar range to maintain equilibrium and prevent water imbalance.
Step-by-step explanation:
Osmolarity of Body Fluids
In human physiology, osmolarity is a measure of the solute concentration in a solution, particularly body fluids. Both the extracellular fluid (ECF) and the intracellular fluid (ICF) contribute to the body's overall osmolarity. The ECF, which encompasses all body fluids outside of cells, including blood plasma, interstitial fluid, and lymph, typically has an osmolarity close to that of blood plasma, which ranges from 285 to 295 milliosmoles per liter (mOsm/L). The ICF, representing about 50% of the total body weight, contains fluids within cells and is separated from the ECF by cellular membranes. Even though water and some small uncharged molecules can pass through these membranes, the movement of electrolytes and larger molecules like proteins is tightly regulated, and can involve active transport processes.
It's important to note that while the exact osmolarity values can vary based on several factors, under typical conditions, mammalian cells strive to maintain an osmolarity similar to that of the surrounding extracellular environment to prevent the detrimental effects of excessive water movement between the ICF and ECF.