The osmosis is one of the most important processes needed to achieve the survival of the cell in living things, which is why it is vitally important in the field of biology . It is a word of Greek origin derived from the word “osmos” which translated into Spanish means “impulse” .


What is osmosis?

Osmosis is a phenomenon that is generated at the moment in which two solutions that have different concentrations are separated by means of a semi-permeable membrane through which the solvent diffuses towards the liquid of lower concentration.

  • Definition
  • Osmosis characteristics
  • Types of osmosis
  • Explanation of the process
  • What is it for
  • Importance
  • Examples of osmosis


Osmosis can be defined as the movement of a solvent which passes through a semipermeable membrane . It is a process that occurs between two solutions that have a different concentration . It is a physical phenomenon that can occur spontaneously without any type of energy expenditure.


Osmosis characteristics

The main characteristics of osmosis are mentioned below:

  • It is considered both a physical and a chemical process .
  • You need a semi-permeable membrane to be able to carry out the complete process.
  • You do not need any type of energy expenditure .
  • It is a vital process for all living beings.
  • To function it needs a medium which can be hypotonic , hypertonic or isotonic .
  • It is characterized by balancing solutions in order to avoid instabilities.
  • You can carry out the entire purification process in a single step and also continuously.

Types of osmosis

There are two different types of osmosis which are explained below:

  • Direct osmosis : this type of osmosis occurs in all cells that make up living beings to which water can enter or leave through plasma membranes, generating an adequate balance with the environment. In some cases, when the process occurs in media with large or small amounts of solutes, dehydration may occur .
  • Reverse osmosis : in this case, the mechanism is practically the same as the previous one but in the completely opposite or opposite direction , which makes it possible for the water or solvent to flow from a point of higher concentration to one that has a lower concentration.

Explanation of the process

The process for osmosis to take place begins when there are two solutions that have different concentrations . When the liquid moves through the semi-permeable membrane , it does so with the sole objective of being able to establish an optimal balance between the concentrations involved in the process.

The solvent or the substance crosses the membrane, in this step, it should be emphasized that the membrane has a molecular dimension and for this reason, it makes the solute molecules unable to pass but it does allow the solvent to pass. It is in this way that the concentration that has a lower concentration manages to increase the amount of the element and the other, on the contrary, decreases, causing a balance to be established.

This process can occur by means of two different types of transport , one of them is the active one that is generated when the cell has an energy expenditure or it can be passive , when the energy expenditure does not occur since it is not necessary.

What is it for

Osmosis is a process that serves and intervenes in many applications. It is an ideal process to be able to desalinate the water, to eliminate its hardness and to considerably reduce the amount of nitrate ions in the liquid. But in addition, it also has a number of uses in other areas.

In the industrial field , osmosis is used to produce large quantities of high quality water, to reduce the amount of microorganisms present in the liquid and to purify it. It is also used in cooling circuits in order to save money and avoid corrosion of the materials that make up the circuits. It is the ideal medium for textile factories to dye their materials and is also used in the manufacture of catalysts.

The process also has an important role in food as it is used to better concentrate the molecules of the food, thus guaranteeing its good quality. It is used to produce concentrates of juices of fruits and vegetables, to produce potato starch and to produce milk serum .

Finally, it is an important piece in the water maintenance of living beings since it is the means by which the water levels in cells and in the body can be correctly regulated. Without this process, the human being would not have the ability to regulate the fluids that enter the body and nutrients could not be absorbed either. It purifies the blood and lymph , improves the functioning of cells and tissues , helps improve recovery time from diseases and helps reduce the accumulation of fluids in tissues.


Osmosis is a process of vital importance, mainly for the metabolism of cells, since this is the means by which an adequate exchange between the outside and the inside of the cell can be carried out without generating energy costs. It is a term that explains the way in which life originates.

This process also intervenes in many of the activities that are carried out on a daily basis and in the field of industry, mainly in industrial processes related to refrigeration . It is a dynamic process that has chemical , physical , biological, plant, animal and human importance.

Examples of osmosis

Some examples of osmosis that are very easy to recognize are the following:

  • When plants take water through their roots, they have osmotic walls that are permeable and that make it possible for the liquid to reach the rest of the plant.
  • The large intestine that has the ability to take in water through the epithelial glands that are permeable and that allow the passage of water but not of waste substances.
  • When a person sweats , the water comes out through the skin in order to balance the body temperature.
  • Salinization plants that have filters which in turn have permeable membranes which allow the passage of water, preventing the salt from passing through.

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