Qhov sib txawv tseem ceeb ntawm Nernst muaj peev xwm thiab cov peev txheej membrane yog tias Nernst muaj peev xwm yog qhov muaj peev xwm hla cov cell membrane uas tawm tsam cov net diffusion ntawm ib qho tshwj xeeb ion los ntawm daim nyias nyias, whereas membrane muaj peev xwm yog qhov txawv ntawm qhov hluav taws xob muaj peev xwm ntawm sab hauv thiab hluav taws xob muaj peev xwm ntawm sab nrauv ntawm lub hlwb lom.
Nernst peev xwm thiab daim nyias nyias yog cov ntsiab lus tseem ceeb hauv biochemistry. Feem ntau, tib neeg siv cov lus no sib hloov, txawm tias lawv muaj qhov sib txawv me ntsis.
Nernst Potential yog dab tsi?
Nernst muaj peev xwm (tseem hu ua qhov muaj peev xwm thim rov qab) yog lub peev xwm hla lub cell membrane uas tawm tsam cov net diffusion ntawm ib qho tshwj xeeb ion los ntawm daim nyias nyias. Lo lus no muaj nws cov ntawv tseem ceeb hauv biochemistry. Txhawm rau txiav txim siab lub peev xwm Nernst, peb tuaj yeem siv qhov sib piv ntawm qhov ntau ntawm cov ion tshwj xeeb (uas yog sim hla lub cell membrane) hauv lub cell thiab sab nraud ntawm tes. Tsis tas li ntawd, lo lus no kuj tseem siv tau rau hauv electrochemistry txog electrochemical hlwb. Qhov sib npaug uas peb siv los txiav txim siab txog Nernst muaj peev xwm yog Nernst kab zauv.
Nernst equation yog ib qho kev qhia lej uas qhia peb txog kev sib raug zoo ntawm qhov txo qhov peev xwm thiab tus qauv txo qhov peev xwm ntawm cov hluav taws xob hluav taws xob. Qhov kev sib npaug no tau muaj npe tom qab tus kws tshawb fawb W alther Nernst. Ntxiv mus, Nernst kab zauv nyob ntawm lwm yam uas cuam tshuam rau electrochemical oxidation thiab txo cov tshuaj tiv thaiv, xws li kub thiab tshuaj lom neeg kev ua si ntawm cov tshuaj hom tshuaj uas undergo oxidation thiab txo.
Thaum muab qhov sib npaug Nernst, peb yuav tsum xav txog cov qauv kev hloov pauv hauv Gibbs dawb lub zog uas cuam tshuam nrog kev hloov pauv hluav taws xob uas tshwm sim hauv lub cell. Kev txo cov tshuaj tiv thaiv ntawm ib qho hluav taws xob hluav taws xob tuaj yeem muab tau raws li hauv qab no:
Ox + z e– ⟶ Red
Nyob rau hauv thermodynamics, qhov tseeb dawb lub zog hloov ntawm cov tshuaj tiv thaiv yog, E=Ereduction – Eoxidation
Peb tuaj yeem cuam tshuam Gibbs dawb zog (ΔG) rau E (muaj peev xwm sib txawv) raws li hauv qab no:
ΔG=-nF
Qhov twg n yog tus naj npawb ntawm cov hluav taws xob hloov pauv ntawm cov tshuaj lom neeg thaum cov tshuaj tiv thaiv nce ntxiv, F yog Faraday tas li. Yog tias peb xav txog cov qauv txheej txheem, ces qhov sib npaug yog raws li hauv qab no:
ΔG0=-nFE0
Peb tuaj yeem cuam tshuam Gibbs dawb lub zog ntawm cov xwm txheej tsis zoo nrog Gibbs lub zog ntawm cov qauv txheej txheem los ntawm kev sib npaug hauv qab no.
ΔG=ΔG0 + RTlnQ
Tom qab ntawd, peb tuaj yeem hloov qhov sib npaug saum toj no rau hauv cov qauv sib npaug no kom tau txais Nernst kab zauv raws li hauv qab no:
-nFE=-nFE0 + RTlnQ
Tom qab ntawd Nernst kab zauv yog raws li nram no:
E=E0 – (RTlnQ/nF)
Membrane Potential yog dab tsi?
Membrane peev xwm (tseem hu ua transmembrane peev xwm lossis membrane voltage) yog qhov sib txawv ntawm cov hluav taws xob muaj peev xwm ntawm sab hauv thiab hluav taws xob muaj peev xwm ntawm sab nrauv ntawm lub xov tooj ntawm tes. Ntawm lawv, sab nrauv hluav taws xob muaj peev xwm ntawm ib lub xovtooj feem ntau yog muab rau hauv chav tsev ntawm millivolts (mV), thiab tus nqi ntawm -40 mV txog -80 mV.
Nyob rau hauv biology, tag nrho cov tsiaj hlwb muaj ib puag ncig daim nyias nyias uas muaj ib tug lipid bilayer uas muaj proteins uas yog embedded nyob rau hauv lub bilayer. Qhov no daim nyias nyias muaj peev xwm ua raws li ib tug insulator thiab raws li ib tug diffusion barrier uas tuav lub zog ntawm ions. Muaj cov proteins transmembrane uas ua raws li cov khoom thauj ion lossis cov twj ion. Lawv tuaj yeem thawb ions thoob plaws hauv daim nyias nyias, tsim kom muaj kev sib haum xeeb gradient hla daim nyias nyias. Cov ion twj tso kua mis thiab cov ion channel yog hluav taws xob sib npaug rau cov roj teeb thiab cov resistors. Yog li ntawd, cov khoom no tuaj yeem tsim qhov voltage ntawm ob sab ntawm daim nyias nyias.
Yuav luag txhua cov plasma daim nyias nyias muaj lub peev xwm hluav taws xob thoob plaws hauv daim nyias nyias, muaj qhov tsis zoo rau sab hauv thiab tus nqi zoo rau sab nraud. Muaj ob txoj haujlwm tseem ceeb ntawm lub peev xwm hluav taws xob no: tso cai rau lub xov tooj ntawm tes ua haujlwm raws li lub roj teeb thiab xa cov teeb liab ntawm qhov sib txawv ntawm ib lub xov tooj.
Qhov txawv ntawm Nernst Peev Xwm thiab Membrane Potential yog dab tsi?
Nernst peev xwm thiab daim nyias nyias yog cov ntsiab lus tseem ceeb hauv biochemistry. Feem ntau, tib neeg siv lawv sib hloov, txawm tias lawv muaj qhov sib txawv me ntsis. Qhov sib txawv tseem ceeb ntawm Nernst muaj peev xwm thiab membrane muaj peev xwm yog tias Nernst muaj peev xwm yog qhov muaj peev xwm hla lub cell membrane uas tawm tsam cov net diffusion ntawm ib qho ion los ntawm daim nyias nyias, whereas membrane muaj peev xwm yog qhov sib txawv ntawm lub peev xwm hluav taws xob ntawm sab hauv thiab hluav taws xob. muaj peev xwm ntawm sab nrauv ntawm ib lub cell lom.
Summary – Nernst Potential vs Membrane Potential
Nernst peev xwm thiab cov peev txheej membrane yog cov ntsiab lus tseem ceeb hauv biochemistry. Qhov sib txawv tseem ceeb ntawm Nernst muaj peev xwm thiab membrane muaj peev xwm yog tias Nernst muaj peev xwm yog qhov muaj peev xwm hla lub cell membrane uas tawm tsam cov net diffusion ntawm ib qho ion los ntawm daim nyias nyias, whereas membrane muaj peev xwm yog qhov sib txawv ntawm lub peev xwm hluav taws xob ntawm sab hauv thiab hluav taws xob. muaj peev xwm ntawm sab nrauv ntawm ib tug kab mob lom.
