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6.4.5. Plasma membrane differentiations

Membrane differentiations

In some areas of the membrane, cells can exhibit specific adaptations depending on the function performed by the cell, such as increasing the cell surface area. Some of these differentiations are:

  • The microvilli are fingerlike extensions of the membrane of the epithelial cells of the intestine, in the area facing the interior of the tube, which allows them to expand its surface with which they absorb nutrients.

By BallenaBlanca (Own work) [CC BY-SA 4.0], via Wikimedia Commons

  • The invaginations appearing in cells lining the tubule of the nephron (kidney cells). The increased surface area allows more water to return to the blood.
  • The intercellular junctions occur in the lateral surfaces of the cells and allow contact between neighboring cells, causing the cells remain adhered. There are several types of unions:
    • Waterproof joints: they do not leave any space between cells and act as a barrier, preventing the passage of substances. They are frequent among epithelial cells.

By Cellular tight junction-en.svg: LadyofHatsderivative work:Miguelferig [CC0], via Wikimedia Commons

  • Adherent junctions (desmosomes): they leave a space between cells. In the internal part of the plasma membrane, a dense material appears, called desmosomal plaque, towards which bundles of intermediate filaments of the cytoskeleton are directedThese joints appear in tissues that are subjected to mechanical stress .

By Desmosome cell junction en.svg : LadyofHats (Mariana Ruiz)derivative work:Miguelferig [CC0], via Wikimedia Commons


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.