Osmosis refers to the net movement of molecules of a solvent from a lowly concentrated solution to a highly concentrated solution across a partially permeable membrane. According to Xu, Eisenberg, Song & Huang (2018), the partially permeable membrane is also known as a semi-permeable membrane, and without it, the movement of molecules of a solvent cannot be called osmosis.
The three main compartments of the body are plasma, interstitial fluid, and intracellular fluid. Osmosis works in the three fluid compartments by allowing water molecules to move from a highly concentrated compartment to a lowly concentrated compartment through a semi-permeable membrane. The water movement in the body moves in and out tissues and cells based on the corresponding concentrations of solutes and water present there. According to Goodhead & MacMillan (2017), osmosis ensures the normal body functioning by balancing solutes outside and inside the body cells.