Mikrovillusok

Mikrovillusok are microscopic, finger-like projections that extend from the surface of certain cells. They are found on the apical surface of epithelial cells, particularly in tissues where absorption is a primary function. The most well-known examples are found in the lining of the small intestine and the kidneys. Their primary role is to significantly increase the surface area available for absorption of nutrients, water, and other substances. By folding the cell membrane in this way, the efficiency of uptake is greatly enhanced.

Structurally, mikrovillusok are composed of a core of actin filaments, which are cytoskeletal proteins. These filaments provide support and allow for some limited movement. The membrane of the mikrovillus is continuous with the cell membrane and contains various transport proteins and enzymes crucial for their absorptive function. In the small intestine, for instance, the mikrovillus membrane houses enzymes that complete the digestion of carbohydrates and peptides, as well as numerous transporter proteins that move digested molecules into the cell. The collective formation of mikrovillusok on a cellular surface is often referred to as a brush border or striated border due to its appearance under a microscope. Their presence is a key adaptation for efficient nutrient and fluid absorption in multicellular organisms.