The cell membrane, also known as the plasma membrane, is a thin, flexible barrier that surrounds every living cell, separating the interior of the cell from the external environment
. It is primarily composed of a lipid bilayer with embedded proteins, cholesterol, and carbohydrates, which together provide structural support and regulate the membrane's fluidity
. Functions of the Cell Membrane:
- Selective Barrier: It acts as a selective filter, controlling what substances enter and exit the cell. This includes allowing essential nutrients in and waste products out while keeping harmful substances and toxins out
- Transport Regulation: The membrane regulates transport through passive processes like diffusion and osmosis, and active transport mechanisms that require energy to move substances against concentration gradients
- Cell Communication and Interaction: Proteins on the membrane surface enable the cell to interact with other cells and its environment, facilitating cell signaling and adhesion
- Structural Support: It anchors the cytoskeleton inside the cell to maintain shape and attaches to the extracellular matrix and other cells to form tissues
- Protection: The membrane protects the cell’s internal components, maintaining a stable internal environment necessary for cellular function
- Maintaining Cell Potential: It helps maintain the electrical potential across the membrane, important for processes like nerve impulse transmission
In summary, the cell membrane is essential for protecting the cell, regulating its internal environment, mediating communication, and controlling the transport of substances necessary for the cell’s survival and function
