Crenation occurs because in a hypertonic environment, (that is, the cell has a lower concentration of solutes than the surrounding extracellular fluid), osmosis (the diffusion of water) causes a net movement of water out of the cell, causing the cytoplasm to decrease in its volume. As a result the cell shrinks.
The effects of crenation are especially visible in red blood cells, or erythrocytes, as they become distorted in shape rather than maintaining the usual disc-like shape with the dimple that the blood cell normally has. Instead, the red blood cell looks as if it has legs extending from a smaller central area, like a spiked ball.
Plasmolysis is the term which describes plant cells when the cytoplasm shrinks from the cell wall in a hypertonic environment. In plasmolysis, the cell wall stays intact, but the plasma mebrane shrinks and the chloroplasts of the plant cell concentrate in the center of the cell. Cytolysis is the term which describes the bursting of cells without cell walls in a hypotonic environment. If a red blood cell were exposed to pure water with a solute concentration of zero, the diffusion of the water or osmosis would diffuse from a concentration of low to high. The pure water is considered a hypotonic solution and enters the red blood cell. Hemolysis occurs if too much water enters the red blood cell, causing it to burst. Hemolysis gets its name from the prefix hemo- which means blood and the suffix -lysis which means destruction or dissolution.
In an isotonic solution, the concentration of the solute in the solution outside of the cell equals the concentration of the solute inside of the cell so there is no net change in the concentrations of either solution.
Researchers from Aarhus University provide details of new studies and findings in the area of Escherichia coli.
Jun 01, 2010; New investigation results, 'Escherichia coli alpha-hemolysin triggers shrinkage of erythrocytes via K(Ca)3.1 and TMEM16A channels...