What is Osmosis?

What is osmosis? The term ‘osmosis’ in science refers to a process where by there is a diffusion of a solvent (water molecules) across a selectively permeable membrane from an area of less concentration of solutes (such as salt molecule) into an area of higher concentration of solutes. The process of osmosis is considered a passive movement, and does not require energy to achieve this movement of water. Although osmosis is considered a passive process it does cause the movement of water, and this does reflect some form of kinetic energy. The energy that osmosis utilises can be seen causing the movement of water, which releases kinetic energy.

What is the Significance of Osmosis?

Basically, this concept becomes important when we start to administer hypertonic (lots of minerals) or hypotonic solutions (lots of fluid). We understand that if we were to admister 100% sterile water intraveneously to patients who are dehydrated, the cells within the vasculature (blood vessels) would draw up all that fluid due to the osmotic gradient shift (this basically means that the fluid will want to shift into the cells) and this will cause the local cells to swell and lyse (rupture). This means that the red blood cells themselves will no longer be capable of carrying oxygen and serving their purpose.

Likewise, if you were to administer 50% glucose intravenously, the hypertonic solution (lots of solutes) will cause a lot of fluid to shift towards it. Now, so long as the canula is in a large vein, it will be able to draw fluid from a large area. However, if the canula is inserted in a small vein or accidentally inserted into the intersitial space and not a vein, it will not be able to draw fluid from all over, and consequently draw all the fluid from the surrounding cells. This will cause the cells to shrink (crenate) and again, become unable to sustain life. In these circumstance, patients may develop cellulitis or damaged veins.

How to Remember What Osmosis is

When trying to remember what osmosis is, think ‘salt sucks’ – because wherever salt goes, fluid will be sucked into following.