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Cell membrane

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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The plasma membrane delimits the internal environment of the cell from the extracellular fluid. It is about 10 nanometres in diameter. Its basic structure is that of a lipid bilayer with hydrophilic external surfaces and a hydrophobic core. Proteins sit within the membrane and carbohydrate is attached to its outer surface. The components are thought to behave like a fluid-mosaic. Electron microscopy on freeze-fracture samples has largely revealed the membrane structure.

It is vital to cell function:

  • provides physical protection
  • it actively works to transport and exclude certain molecules from the cell, so:
    • maintaining a favourable environment for cell metabolism
    • keeping ions such as calcium low, so permitting its use as an intracellular signalling molecule
    • establishing an electrical potential across the membrane - making cells 'excitable' - which allows specialization for function e.g. myocytes, neurons
  • it has receptors for a wealth of transmitters, hormones and chemical mediators with adaptations to transduce the signal internally
  • it is involved in intercellular and cell-matrix interaction
  • it has surface molecules involved in immune recognition

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The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.

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