Ion Channels: Structure and Function. Ion channels are membrane protein complexes and their function is to facilitate the diffusion of ions across biological membranes. Membranes, or phospholipid bilayers, build a hydrophobic, low dielectric barrier to hydrophilic and charged molecules. They are electrical insulators.
The inert gas xenon (chemical symbol Xe) has an atomic number of 54, and it has 54 protons in its nucleus. The number of neutrons varies, however.
Xenon-129, a stable isotope that makes up about a quarter of naturally occurring xenon, turns out to be ideal for use in magnetic resonance imaging. Usually these instruments only detect hydrogen nuclei in water and fats-ideal for most tissue, but are of no use when looking at air spaces such as the lungs.