Explain these 3 terms in relation to cells and osmosis: isotonic, hypertonic and hypotonic?

These 3 terms all describe the 3 possible concentrations of a solution in respect to the water potential surrounding a cell.Isotonic solution (Iso=same and tonic=strength) is where the extracellular fluid has the same osmolality as the cell (i.e. the solution on the outside of a cell is equal to that on the inside of a cell). This means that although water is still diffusing through the membrane, is it doing so equally in both directions so that there is no net flow of water, keeping the cell at its normal, usual state.Hypertonic solutions mean there is a higher amount of solutes in the water, meaning a lower water potential. In other words, the extracellular fluid has a higher osmolality than the cells cytoplasm (hyper means greater than). This means the cell shrinks due to the water diffusing down its concentration gradient from the high-water potential (inside the cell) to the lower water potential (outside the cell).Hypotonic solutions on the other hand is the opposite, whereby there is a smaller concentration of dissolved solutes and thus a higher water potential. This means that the extracellular fluid has a lower osmolality than the fluid inside of the cell (hypo means less than). So, the net flow of water will be into the cell (by osmosis) from the higher water potential on the outside of the cell to the lower water potential on the inside of the cell. This effectively causes the cell to become swollen and can sometimes cause it to ‘burst’, through a process called osmotic lysis.Note:When using these terms, we are describing solutes which are unable to cross the membrane.These 3 terms are also relative terms à they describe how one solution compares to another in terms of osmolality. For example, if the cells fluid has a higher osmolarity (concentration of solute), than the extracellular fluid, the fluid in the interior is hypertonic to the extracellular fluid, and the extrcellular fluid is hypotonic to the cell interior.Helpful Tip I was able to distinguish easily between these terms by making up a little association in my head between the letters in the term and what happens to the cell in that solution. This then meant I could work out whether it was a higher or lower water potential in the extracellular fluid. This may or may not work for you, but I suggest trying to think of something that does, or ensure you fully know these terms as they can easily be mixed up (especially in the panic of an exam).Hypertonic solutions means the cell becomes smaller, due to a higher solute concentration (thus lower water potential) on outside of cell.Hypotonic solutionà means the cell becomes swollen, due to a lower solute concentration (thus a higher water potential) on outside of cell.