mikrovillilla

Mikrovillilla are microscopic, finger-like projections that extend from the surface of certain cells. Their primary function is to significantly increase the surface area available for absorption or secretion. These structures are particularly abundant in cells lining the intestines and kidneys, where efficient absorption of nutrients and reabsorption of water and electrolytes are crucial. The increased surface area provided by mikrovillilla allows these cells to absorb substances much more rapidly than they would be able to without them.

Each mikrovillus is supported internally by a bundle of actin filaments, which are part of the cell's cytoskeleton. This internal structure provides mechanical support and also plays a role in the movement and trafficking of absorbed substances. The surface of the mikrovillilla is covered by the plasma membrane, which contains various transport proteins and enzymes necessary for specific absorption and digestive processes. In the small intestine, the collective appearance of dense mikrovillilla on the apical surface of epithelial cells forms a brush border, a key feature for maximizing nutrient uptake. The size and density of mikrovillilla can vary depending on the cell type and its specific function, but their fundamental role in enhancing surface area remains consistent.