OSMOSIS

        When water diffuses the process is called osmosis.  Water moves from a high concentration of water (less salt or sugar dissolved in it) to a low concentration of water (more salt or sugar dissolved in it).  This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it).

 Water can cross the cell membrane through the lipid bi-layer and with special proteins. If enough water enters the cell by osmosis, the cell can swell enough to burst open and die.  This is demonstrated in the picture below.

Picture:    In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it).  Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS.  In this case too much water enters and the cell swells to the point of bursting open.  In the end pieces of cell membrane are left in the water.  Pieces of red blood cell membranes are known as red blood cell ghosts. 

 

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This page was created by Patrick Ireland (Patric@ireland.com).It was last updated 08/22/00