The cell membrane maintains homeostasis by regulating the movement of
molecules from inside and outside of the cell. The cell membrane keeps the cell in balance.
The cell membrane is able to keep the cell in balance because it acts similar to a strainer. A strainer allows some materials to pass through and blocks others. A membrane that allows materials to pass through is called permeable. A membrane that blocks materials from passing throuhg is called impermeable. A strainer allows liquid and small materials to pass through the openings. Materials that are bigger than the pores will not pass freely. Membranes that allow some substances to pass across it and not others are called semipermeable, or selectively permeable. The structure of the cell membrane enables it to act as a selectively permeable barrier.