polopropustnost

Polopropustnost, often translated as semipermeability or selective permeability, describes the property of a barrier that allows certain molecules or ions to pass through by diffusion, while others are blocked. This selective passage is crucial in many natural and artificial processes. In biological systems, cell membranes exhibit polopropustnost, controlling the movement of substances into and out of the cell, which is essential for maintaining cellular homeostasis, nutrient uptake, and waste removal. The membrane's structure, typically a lipid bilayer with embedded proteins, dictates which molecules can cross.

The degree of polopropustnost can vary. Some barriers are highly selective, allowing only specific small molecules like water to pass, while others are less discriminating, permitting a wider range of substances. This property is utilized in various technologies. For instance, reverse osmosis, a water purification technique, relies on a semipermeable membrane to remove dissolved salts and other impurities from water under pressure. Dialysis, used to treat kidney failure, employs a semipermeable membrane to filter waste products from the blood. Understanding polopropustnost is fundamental to fields ranging from biology and chemistry to engineering and environmental science.