The phenomenon of osmotic swelling is a concept that is used to explain how cells in solution can gain or lose water as they interact with a surrounding solvent. Essentially, when a solution is placed in contact with a solvent, the latter tends to draw water away from the solution. This is known as osmotic pressure. In the case of living cells, osmosis is vital for their maintenance of balance and equilibrium, as it allows them to remain in an environment with adequate water levels while maintaining a stable internal composition.
The most basic way to explain osmotic swelling is to consider the example of a soaker hose. A soaker hose is essentially a tube with perforations. When the hose is filled with water and placed in contact with a low-pressure environment, water begins to pass through the tiny holes and is drawn in by the low external pressure. This is simply another way of saying that the soaker hose is experiencing osmotic pressure, as the pressure inside is greater than the pressure outside.
In living cells, osmotic swelling occurs because the cell creates a distinct environment within itself. This environment consists of a higher concentration of solutes, i.e. molecules or ions with which the cell can interact. The cell is said to be hypertonic and, in response, the environment outside the cell is said to be hypotonic. In other words, the cell wall acts as a semi-permeable membrane, as it only allows certain molecules and ions to pass through. In situations where the environment outside is hypersonic, water will be drawn in from the surroundings, resulting in the cells swelling due to hyperosmotic swelling.
This phenomenon is thought to play a role in causing certain cell and tissue damages when there is an imbalance in the solute concentrations of the external-internal environment. When the environment outside of the cell has a higher solute concentration, it is said to be hyperosmotic, and this means osmotic swelling will occur, leading to cells and tissues swelling with fluid and ultimately, cell death. Similarly, when the environment outside of the cell has a lower solute concentration, it is said to be hypo-osmotic and the cell will result in shrinkage due to dehydration.
Osmotic swelling occurs in animals at a cellular level to maintain fluid balance, but it also plays a role in larger animals as well. When sea animals or invertebrates inhabit salty waters, osmotic pressure helps them absorb and maintain water balance, as the external environment is typically more salty than the cellular environment.
Finally, osmotic swelling can also be utilized in industrial applications. For example, in pharmaceuticals and food products, the process is used to create specific shapes and sizes. This is because when a gelatin, alginate or other hydrophilic polymer is placed in contact with a solvent such as water, salt or alcohol, the hydrophilic molecules gain water and swell as a result of the increased osmotic pressure. This swelling can be used to create specific shapes or sizes if desired.
In conclusion, osmotic swelling is a phenomenon wherein hydrostatic pressure of the immediate environment leads to diffusion of water molecules into or out of the cell, depending on the concentration of the solute in the surroundings. In living organisms, it occurs to maintain a balance in internal environment by counteracting osmotic pressure. It is also used in a variety of industrial applications, such as the creation of gelatin-based products.
