Osmosis is the movement of solvent particles across a semipermeable membrane from a dilute solution into a concentrated solution. The solvent moves to dilute the concentrated solution and equalize the concentration on both sides of the membrane. The movement of liquids in and out cells is dependent on the concentration of the solution surrounding it.
There are 3 types of situations in which this could vary:
1. Isotonic: Here the concentration of external and internal solution of the organism are the same.
2. Hypotonic: Here the external solution concentration is less compared to the concentration of the inner solution of an organism. In this case water will rush into the organism.
3. Hypertonic: Here the external solution concentration is greater than the concentration of the inner solution of an organism. In this case the water will rush out of the organism.
Example: Red blood cells.
1. When red blood cells are placed in hypertonic solution, water flows out of the cell faster than it comes in. This results in shrivelling of RBC.
2. On the other hand if RBC is hypotonic, more water will flow into the cell than out. This results in swelling of the cell and followed by bursting.
3. If the RBC is placed in an isotonic solutions, the flow of water in and out of the cell will happen at the same rate.
