Osmosis is a physical-chemical process that takes place in cells and in various areas.
Osmosis is a physical-chemical process that refers to the passage of a solvent , although not a solute , between two solutions that are separated by a membrane with semipermeability characteristics. These solutions, on the other hand, have different concentrations.
It is in Greek where we can find the etymological origin of the term osmosis, also accepted as osmosis . Specifically, it can be established that it comes from the word osmosis , which is made up of two very different parts: osmos , which means "impulse" , and the suffix -sis, which can be translated as "action" .
Development of osmosis
A semipermeable membrane is one that contains pores of molecular size . As the size of these pores is very small, only the smallest molecules can pass through the membrane, but not the largest ones.
This means that, if one of these membranes is responsible for separating a liquid and dividing it into two partitions, various phenomena will occur that are explained from the notions of electrochemical potential and simple diffusion .
The first concept is linked to the fact that, when adding the potential of the components of a solution, the result will be higher than that of the chemical components of each of them. Due to this lack of equilibrium, the solvent particles will flow towards the area that has the lowest potential, something known as measurable osmotic pressure . The solvent, for its part, will be directed towards the solute to achieve a balance of the potential or to ensure that the hydrostatic pressure can balance the osmotic pressure.
Reverse osmosis can be used to purify water.
Classification according to type
More precisely, we can determine that there are two clearly differentiated types of osmosis. Thus, first of all, we find the so-called phenomenon of direct osmosis , which is that natural process that takes place in all living cells and its result is the extraction of pure water from the environment.
And then secondly, we find reverse osmosis . This is not a phenomenon resulting from nature but rather a process created by the human being himself and which consists of “turning around” the previous type of osmosis. Hence, the goal is to obtain purified water, taking an area of salty or impure water as a starting point.
The way to achieve this objective is by boosting the pressure so that the passage of water occurs through what is a semipermeable membrane. And all this in the opposite direction to what takes place naturally.
It should be noted that those aqueous media that show separation due to the presence of a semipermeable membrane can be classified differently depending on their concentration. When the medium has a reduced concentration of solutes compared to others, it is referred to as hypotonic . On the other hand, when this concentration is high, it is called hypertonic .
It must be considered that a water molecule passes from the hypotonic to the hypertonic medium, generating an increase in pressure on the side of the membrane in the hypotonic zone. That is what is known as osmotic pressure . Thanks to the process, the concentration gradient ends up equalizing and isotonic equilibrium is reached.
Osmosis in the human body is essential for survival.
Examples of osmosis
Among the examples that we can establish to understand the reverse osmosis process are some as simple as the one used to concentrate the whey of cheese or remove alcohol from beer, as well as the water used for irrigation.
Suppose a chard leaf is removed from a plant. The leaf will end up drying out due to dehydration. However, if said dry leaf is placed in a container with water, its hydration will be achieved again by virtue of osmosis. Thus, the chard leaf will recover its original texture.
It is important to highlight that osmosis is a phenomenon that has great importance in the physiology of the cells of humans and animals. The cell membrane is semipermeable: in a hypotonic medium, water enters the cell, increasing its volume and causing a drop in the osmotic pressure inside. There is, therefore, a swelling of the cell. On the other hand, in a hypertonic medium, water leaves the cell, osmotic pressure increases and cell volume is reduced. This leads to plasmolysis , with the membrane separating from the cell wall.
To avoid any disorder, osmoregulation is key. Also called osmotic regulation , osmoregulation is an active process that makes it possible to maintain osmotic pressure at the appropriate level. It cannot be ignored that metabolic reactions take place in a liquid environment and that they require that the relative concentrations of solutes and water do not go beyond certain limits. With osmoregulation, then, the homeostasis of the body is maintained.
The concept, on the other hand, is used to name the reciprocal influence that occurs in individuals who are part of the same group.