Semipermeable membrane

Schematic of semipermeable membrane during hemodialysis, where blood is red, dialysing fluid is blue, and the membrane is yellow.

Semipermeable membrane is a type of synthetic or biologic, polymeric membrane that allows certain molecules or ions to pass through it by osmosis. The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Depending on the membrane and the solute, permeability may depend on solute size, solubility, properties, or chemistry. How the membrane is constructed to be selective in its permeability will determine the rate and the permeability. Many natural and synthetic materials which are rather thick are also semipermeable. One example of this is the thin film on the inside of an egg.[1]

Biological membranes are selectively permeable,[2] with the passage of molecules controlled by facilitated diffusion, passive transport or active transport regulated by proteins embedded in the membrane.

  1. ^ "Osmosis Eggs | Center for Nanoscale Science". www.mrsec.psu.edu. Center for Nanoscale Science, Penn State University. Retrieved 2 July 2021.
  2. ^ Caplan, M.J. (2017). "Functional organization of the cell". In Boron, W.F.; Boulpaep, E.L. (eds.). Medical physiology (Third ed.). Philadelphia, PA: Elsevier. pp. 8–46. ISBN 9781455743773.