Osmosis vs. Dialysis

Difference Between Osmosis and Dialysis

Those who are students of science are aware of osmosis is an important biological process going on inside the cells of all plants and animals. It is the process of passage of water via a semi-permeable membrane from a region of high water concentration to a region of low concentration of water. Most people are aware of the word reverse osmosis, the credit being of the several water purification companies in the market. There is another term dialysis, which is a word of terror for many as it refers to the help given to a patient who has suffered from renal failure as his/her kidneys can not purify the blood alone. Both processes however, perform the same function of purification, however, it is interesting to know the aspects that separate these two processes. This article attempts to highlight the differences between osmosis and dialysis.

What is Osmosis?

Osmosis is actually the movement of water molecules through a semi-selective permeable membrane (the cell membrane is such a barrier), which allows the passage of water in the region of low solute concentration to a high concentration of solute. This process is unique in the sense that the barrier does not allow passage of larger molecules such as starch and protein. And osmosis involves the passage of solvent from one side of the membrane to the other side.

What is Dialysis?

On the other hand, dialysis is the process of purification of blood by the kidneys where the material is excreted unused blood and kidney cleansing the blood. In short, dialysis facilitates selective passage of solutes.

The difference between osmosis and dialysis

The concepts of osmosis and dialysis find important applications in the field of water purification and medicine. Osmosis tells us how a man, who drinks salty ocean water, is dehydrated and dies. The same concept is also applicable in case of freshwater fish when it is placed in standing water or brackish water in the ocean. Plants for water treatment, clinical analysis and process of sterilization make use of the process of osmosis to remove impurities dissolved in water.

Dialysis is used primarily to provide assistance to patients suffering from kidney failure as their kidneys can not perform the purification of blood alone. This is known as hemodialysis where the blood of the arteries of the patient is sent by a machine called a hemodialyzer (artificial kidney) that removes impurities and waste materials of ​​the blood and the blood is sent back to the arteries. Another process called peritoneal dialysis is also employed to clean the patient’s blood inside the body. The machine that purifies the blood makes use of all the three processes viz. ultra filtration, diffusion and osmosis to purify the blood. Although dialysis is necessary for patients with renal failure, it is an artificial process and only a substitute for natural purification of blood by the kidneys. Dialysis however is unable to produce a hormone that is very important for the production of RBC within the body, a process, that occurs naturally during the cleansing of blood by the kidneys.


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