Osmotic Changes in Body Fluids (OCR GCSE Biology A (Gateway))

How Osmosis Affects Animal Cells

• Animal cells lose and gain water as a result of osmosis 

• Body cells are surrounded by tissue fluid which is formed of

  • Water

  • Mineral ions

  • Food substances

  • Dissolved gases

• Tissue fluid has a different water potential to the fluid in the cells and this is what causes the movement of water into or out of the cell

  • If an animal cell is placed into a strong sugar solution (with a lower water potential than the cell), it will lose water by osmosis and become crenated (shrivelled up)

  • If an animal cell is placed into distilled water (with a higher water potential than the cell), it will gain water by osmosis and, as it has no cell wall to create turgor pressure, will continue to do so until the cell membrane is stretched too far and it bursts

• The osmotic balance between animal cell and its surroundings is fundamental as the absence of the cell wall means that effects of osmosis can be severe

Osmotic changes to body fluids has a direct impact on cells