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A Membrane is material layer that is a dynamic barrier between two environments or structure.



  • (Wiktionary, 2018) ⇒ Retrieved:2018-12-23.
    • QUOTE: A flexible enclosing or separating tissue forming a plane or film and separating two environments (usually in a plant or animal).

      A mechanical, thin, flat flexible part that can deform or vibrate when excited by an external force.

      A flexible or semi-flexible covering or waterproofing whose primary function is to exclude water.


  • (Wikipedia, 2009) ⇒
    • A membrane is a layer of material which serves as a selective barrier between two phases and remains impermeable to specific particles, molecules, or substances when exposed to the action of a driving force. Some components are allowed passage by the membrane into a permeate stream, whereas others are retained by it and accumulate in the retentate stream. [1]
    • Membranes can be of various thickness, with homogeneous or heterogeneous structure. Membrane can also be classified according to their pore diameter. According to IUPAC, there are three different types of pore size classifications: microporous (dp < 2nm), mesoporous (2nm < dp < 50nm) and macroporous (dp > 50nm). [2] Membranes can be neutral or charged, and particles transport can be active or passive. The latter can be facilitated by pressure, concentration, chemical or electrical gradients of the membrane process. Membranes can be generally classified into three groups: inorganic, polymeric or biological membranes. These three types of membranes differ significantly in their structure and functionality. [3]


1. endoplasmic reticulum
2. mitochondria
3. nucleus
Membranes are not passive barriers.
1. They control the structures and environments of the compartments they define, and thereby the metabolism of these compartments.
2. The membrane itself is a metabolic compartment with unique functions.
Membranes are dynamic.
1. They can move.
2. Their components are continuously synthesized and degraded.
3. The primary event in cell death (e.g. myocardial infarction) may be damage to the cell membrane, leading ultimately to cell death.