puoliläpäisykalvosta

Puoliläpäisykalvo, or semipermeable membrane in English, is a type of biological or synthetic barrier that allows certain molecules or ions to pass through it by diffusion, while blocking others. The rate of passage depends on the pressure, concentration, and temperature of the molecules or ions on either side of the membrane, as well as the permeability of the membrane to each of them.

This property is crucial for many biological processes. In cells, the plasma membrane acts as a semipermeable membrane, controlling the entry and exit of nutrients and waste products. This selective permeability is essential for maintaining the cell's internal environment, a process known as homeostasis. For example, red blood cells rely on their semipermeable membrane to regulate the passage of water and ions, preventing them from bursting or shrinking.

In kidney function, the glomerulus and tubules contain semipermeable membranes that filter waste products from the blood while retaining essential substances like proteins and blood cells. This filtration process is fundamental to urine formation and maintaining fluid balance in the body.

Synthetic semipermeable membranes have numerous applications in technology. Dialysis machines utilize these membranes to remove waste products and excess fluid from the blood of patients with kidney failure. Reverse osmosis, a process used for water purification and desalination, also relies on semipermeable membranes to separate water from dissolved salts and other impurities under high pressure. These membranes play a vital role in various industrial processes, including food and beverage production, gas separation, and medical treatments.