Mikrovillili

Mikrovillili is a term used to describe the presence of microvilli. Microvilli are microscopic cellular projections that increase the surface area of cells. They are found on the apical surface of many cell types, including those lining the small intestine, kidney tubules, and the surface of many epithelial cells. The primary function of microvilli is to enhance absorption and secretion by increasing the available surface for transport across the cell membrane.

In the context of the small intestine, the dense layer of microvilli on the absorptive cells, known as enterocytes, forms a brush border. This brush border significantly amplifies the surface area, facilitating efficient digestion and absorption of nutrients from food. Similarly, in the kidney tubules, microvilli on the cells lining the tubules aid in the reabsorption of water, ions, and other essential molecules from the filtrate back into the bloodstream.

The structure of microvilli is supported by a core of actin filaments, which are organized in a bundle and anchored to the cell's plasma membrane. This internal scaffolding provides stability and allows for some degree of motility, although they are generally less mobile than other cellular projections like stereocilia. The increased surface area provided by microvilli is crucial for the specialized functions of the cells that possess them, highlighting their importance in physiological processes.