• Osmosis is the?net movement of water molecules?from a region of?higher water potential?(dilute solution) to a region of?lower water potential?(concentrated solution), through a partially permeable membrane
• Like plant cells,?animal cells can also lose and gain water as a result of osmosis
• As?animal cells do not have a supporting cell wall?(unlike plant cells), the results of this loss or gain of water on the cell are more?severe
• For example, if an animal cell is placed in a solution with a?lower water potential?than the cell (such as a concentrated sucrose solution), water will?leave?the cell through its partially permeable cell surface membrane by?osmosis?and the cell will?shrink?and?shrivel up
• This occurs when the cell is in a?hypertonic environment?(the solution outside of the cell has a?higher solute concentration?than the inside of the cell)

• Conversely, if an animal cell is placed in?pure water?or a?dilute solution, water will?enter?the cell through its partially permeable cell surface membrane by?osmosis, as the pure water or dilute solution has a?higher water potential. The cell will continue to?gain?water by osmosis until the cell membrane is stretched too far and the cell?bursts (cytolysis), as it has no cell wall to withstand the increased pressure created
• This occurs when the cell is in a?hypotonic environment?(the solution outside of the cell has a?lower solute concentration?than the inside of the cell)
• This is why a constant water potential?must?be maintained inside the bodies of animals
• If an animal cell is in an?isotonic environment?(the solution outside of the cell has the?same solute concentration?as the inside of the cell), the movement of water molecules into and out of the cell occurs at the?same rate?(no net movement of water) and there is?no change to the cells

Effect of osmosis on animal cells