In medicine, microbiology, cellular physiology and biochemistry a membrane is a lipid bilayer that acts as a boundary to various cellular structures, and can refer to:

• Basement membrane, the combination of the basal lamina and lamina reticularis or of two basal laminae
• Biological membrane
  • Cell membrane
  • Endomembrane system that divides the cell into organelles
  • Outer membrane or inner membrane of an organelle
  • S-layer, a cell membrane of bacteria
• Mucous membrane

• Serous membrane and mesothelium that surround organs, including:
  • Peritoneum that lines the abdominal cavity
  • Pericardium that surrounds the heart
  • Pleura that surround the lungs
  • Periosteum, membrane that surrounds bone
  • The meninges that surround the brain: the dura mater, arachnoid mater, and the pia mater
• Skin, part of the integumentary system

• Artificial membrane/Semipermeable membrane allowing certain molecules or ions to pass through it
  • Proton exchange membrane, designed to conduct protons while being impermeable to gasses
• Branes, in string theory

Membrána | Membran | Membran | Membrana | Membrano | Membrane | Membrano | Membrana | Membraan | 膜 | Membrana | Membrana | Мембрана | Membrane | Membran