What is the difference between hypotonic and hypertonic solutions?

Hypotonic solutions have a lower solute concentration than the cell, while hypertonic solutions have a higher solute concentration.

In more detail, a hypotonic solution is one where the concentration of solutes (such as salts and sugars) is lower outside the cell than inside it. This causes water to move into the cell by osmosis, as water naturally moves from areas of lower solute concentration to areas of higher solute concentration. If a cell is placed in a hypotonic solution, it may swell and even burst due to the influx of water.

On the other hand, a hypertonic solution is one where the concentration of solutes is higher outside the cell than inside it. In this case, water will move out of the cell and into the solution, again due to osmosis. If a cell is placed in a hypertonic solution, it may shrink or shrivel as it loses water.

These concepts are crucial in understanding how cells interact with their environment. For example, red blood cells in the human body must maintain a balance between the intracellular and extracellular fluid to prevent them from either bursting or shrivelling up. This is achieved through the process of osmoregulation, which involves the movement of water and electrolytes across cell membranes to maintain an optimal concentration of solutes.

In a biological context, the terms 'hypotonic' and 'hypertonic' are often used to describe the tonicity of a solution in relation to a cell. If the solution and the cell have the same concentration of solutes, the solution is said to be isotonic. Understanding the difference between hypotonic and hypertonic solutions is fundamental to grasping the principles of osmosis and cell behaviour.