... 15membranetostorechargeatagivenpotential.Thephysicaldimensionsofthemembraneareimportantindeterminingthecapacitance:themoremembrane,themorechargecanaccumulate,thereforethecapacitanceisproportionaltomembranesurfacearea.Thestrengthoftheelectromag-neticfieldthatattractstheionsoneithersideofthemembranedecreaseswithdistance,thereforethecapacitanceisinverselyproportionaltomembranethickness.Thelattervariableturnsouttobenotverymuchofavariableatall:thephospholipidbilayerhasarelativelyconstantthicknessinalllivingcells,certainlyinanimalcells.Finally,theelectro-magneticfieldisalsodependentonthematerialseparatingthetwoconductors(theintracellularandextracellularmedia).Thepropertiesofthemembranepertainingtocapacitancearesummarisedunderthevari-ableofdielectricconstantorεr,andisalsosimilarthroughoutlivingcells.Insummary,capacitancecanbedescribedbyC=Aεrd(2:9)where ... gating mechanism that can close the pore. The gating mechanism isa change in protein conformation. The conformation change can beinitiated by a range of factors that are dependent on the channelspecies. ... ions, as the most important species of anions, were often consid-ered to move passively in reaction to cation transport, but they also havetransporters and ion channels and are therefore an often...