Concept 2 Review

Cells in Isotonic Solutions

When two environments are isotonic, the total molar concentration of dissolved solutes is the same in both of them.

When cells are in isotonic solution, movement of water out of the cell is exactly balanced by movement of water into the cell. A 0.9% solution of NaCl (saline) is isotonic to animal cells. When exposing animal tissues to solutions, it is common to use an isotonic solution such as Ringer's buffered saline so as to prevent osmotic effects and consequent damage to cells.

Click on the "Play" button to see the movement of water molecules through protein channels in the cell membrane in isotonic solution. Note that the number of water molecules on both sides of the membrane remains essentially unchanged.


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