Plasma Membrane

The plasma membrane is the interface between the cellular machinery inside the cell and the fluid outside. It is a selectively permeable lipid bilayer found in all cells The plasma membrane encloses their contents and serves as a semi-porous barrier to the outside environment. The membrane acts as a boundary, holding the cell constituents together and keeping other substances from entering. The plasma membrane is permeable to specific molecules, however, and allows nutrients and other essential elements to enter the cell and waste materials to leave the cell.

The plasma membrane (or cell membrane) surrounds the cytoplasm of a cell and, in animal cells, physically separates the intracellular components from the extracellular environment, thereby serving a function similar to that of skin. The cell membrane also plays a role in anchoring the cytoskeleton to provide shape to the cell, and in attaching to the extracellular matrix to help group cells together in the formation of tissues. The plasma membrane is a barrier which is selectively permeable and able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival.