Functions of the cell membrane in humans include:
1. It maintains the physical integrity of the cell by enclosing the cytoplasm and organelles within it.
2. Forms a barrier between the inside of the cell and the environment outside the cell, enabling different chemical environments to exist on each side of the cell.
3. Active transport. The cell membrane allows active transport of specific molecules across the cell membrane in either direction, that is into or out of the cell.
4. Holds embedded surface protein markers which serve to identify the cell enabling cells to communicate with each other.