Question

The data in the following table were collected from cortical neurons of a rat. Use this information to answer the questions. Ion Intracellular Concentration (mM) Extracellular Concentration (mM) Permeability in Neurons K* Nat Cr 150 15 10 100 160 120 0.002 0.05 0.45

Answer 1

The Gibbs -Donnan effeet 14 i3 a name for the behaviour of chasrged padicles nea a seni- penmeable membrane. tha i Sometimes farls to distribute eventy across the tos sides of the membrane The Presence of cifferent chaed ustances that is una ble to pos through the mem brane and heg create uneven elechnc char → Na and k t- ion, age maj0% contributorゴ usual caus e is the to vm in neurons e have semi pemeable and membrang a miuture of pem a ble ano impenme a ble changeol ionś/moleccu le that could leadl to steady state. The asymmetric ionic grooi ent as well as Perrneabilit leads -to -the drivin? force!Volt across the membrane . Tn en γ0le ot Nat, kt is to maintain the sleody state level and balance the leak Nat. and k+ →The sodium pomp (Nat-kt)in the cell h) embrane The pomp taghe oih the membrane lo uo penmeability to sedium, eectively pre vent sodio for enteig the celul now Nat as the majos m con tribu

-> Nat and k concen tration o not change - Dusin 2 a neuronal action potentiallnge changes Ha kes place in -the membrane potenti al os avecl the Natentry into the cel anol ktenit om the cel. The actual Na ard k concentratias is ida ard outside of the cell enerally da nat change →The total no of Nata, rdkt. ), o ng in the inten- cellulas and estracellulay solutions only a s mall amount numben moves across the neuronal plas ma membrane duing the actian potention In mosf cause ions conce ntra-tio nof char →Dusing action Potential , the NaT inc reas es explosively anduickly,i decr erse because ah not h an -|he very fast dea c tivation Rineti c% of. Nat This - 1n al this Na and k doa net change cha ard the intracell ulas and extracetlul a concentratio o Na and k keeps beirg intact thank s to the continuous action of Na k ard pump and he Juick acti votion ard deactivation of Na and k