I'm sure we've all seen the story about the woman who died after drinking too much water. Today, the Guardian reports that a couple killed a boy they were hoping to adopt, by forcing him to eat salt as a punishment. It would seem to me that these people must have been asleep when their science teacher was discussing osmosis. From Wikipidia:
Osmosis is the net movement of water through a selectively permeable membrane from a region of low solute potential to a region of high solute potential (or equivalently, from a region of high solvent potential to a region of low solvent potential). The partially permeable membrane must be permeable to the solvent, but not to the solute, resulting in a pressure gradient across the membrane. Osmosis is a natural phenomenon. However, it can be artificially opposed by increasing the pressure in the section of high solute concentration with respect to that in the low solute concentration. The force per unit area required to prevent the passage of solvent through a selectively-permeable membrane and into a solution of greater concentration is equivalent to the turgor pressure. Osmotic pressure is a colligative property, meaning that the property depends on the concentration of the solute but not on its identity. Osmosis is an important topic in biology because it provides the primary means by which water is transported into and out of cells.
When you drink too much water, you cause there to be more water outside the cells of your body, than in, which disrupts the delicate balance within the cells. When you eat too much salt (or drink salt water) you create an opposite gradient, where there is more water inside the cell than out (and thus water flows out of it). If you remember only one thing today, let it be this: Too much salt and too much H20 is bad for your health!Go Top