A cell membrane serves as a crucial barrier, separating the interior of the cell from its external environment. It is primarily composed of glycerophospholipids and sphingolipids, which play significant roles in maintaining the structure and function of the membrane. The cell membrane is characterized by its selectively permeable nature, meaning it regulates the movement of substances in and out of the cell.
At the core of the cell membrane is the lipid bilayer, which consists of two layers of lipids. The structure features polar heads that face outward towards the aqueous environments both inside and outside the cell, while the non-polar tails are oriented inward, away from water. This arrangement is essential for the membrane's function, as it helps control the flow of molecules, ensuring that essential nutrients can enter the cell while waste products are expelled. The lipid bilayer's unique properties are fundamental to cellular homeostasis and communication.