Osmosis is the spontaneous movement of solvent molecules, typically water, through a selectively permeable membrane from a region of higher water potential (lower solute concentration) to a region of lower water potential (higher solute concentration). This movement aims to equalize solute concentrations on both sides of the membrane
. In biological systems, osmosis is crucial because cell membranes are semipermeable, allowing water to pass while blocking many solutes. Water moves through membranes via special proteins called aquaporins. Osmosis regulates water transport into and out of cells, maintaining cell turgor and overall fluid balance
. Osmosis can be classified into two types:
- Endosmosis : solvent moves into the cell when placed in a hypotonic solution, causing the cell to swell.
- Exosmosis : solvent moves out of the cell when placed in a hypertonic solution, causing the cell to shrink
Osmotic pressure is the pressure required to stop the net flow of solvent across the membrane and depends on solute concentration, not solute identity
. Examples of osmosis include water absorption by plant roots, regulation of water in animal cells, and the effect of salt solutions on potato slices shrinking due to water loss
. In summary, osmosis is a vital passive process by which water moves across membranes to balance solute concentrations, essential for life functions in plants, animals, and humans.
