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从电学的角度看，质膜在功能上是电阻和电容的组合。电阻的产生是因为质膜阻碍电荷的跨膜运动。电容是这样产生的：脂双分子层非常之薄，以至于膜的一侧积聚的带电粒子产生电场力，将带相反电荷的粒子拉向膜的另一侧。膜电容相对而言不受内嵌的分子的影响，因此其数值相对恒定，约为 2 μF/cm² 左右（一片质膜的总电容与其面积成正比）。另一方面，纯的脂双分子层的电导率非常之低，在生物体中通常由内嵌的分子提供的支路的电导率决定。因此，膜的电容相对是固定的，但电阻是高度可变的。

从电学的角度看，质膜在功能上是电阻和电容的组合。电阻的产生是因为质膜阻碍电荷的跨膜运动。电容是这样产生的：脂双分子层非常之薄，以至于膜的一侧积聚的带电粒子产生电场力，将带相反电荷的粒子拉向膜的另一侧。膜电容相对而言不受内嵌的分子的影响，因此其数值相对恒定，约为 2 μF/cm² 左右（一片质膜的总电容与其面积成正比）。另一方面，纯的脂双分子层的电导率非常之低，在生物体中通常由内嵌的分子提供的支路的电导率决定。因此，膜的电容相对是固定的，但电阻是高度可变的。

质膜厚约 7-8 纳米，非常薄，因此无需很大的跨膜电压就可在其中产生强电场。动物细胞中典型的膜电位大约为 100 毫伏（即十分之一伏特），但计算表明，这种电位产生的电场接近膜所能承受的最大电场——据计算，大于 200 毫伏的电压差可能导致介质击穿，即产生跨膜电弧。

质膜厚约 7-8 纳米，非常薄，因此无需很大的跨膜电位就可在其中产生强电场。动物细胞中典型的膜电位大约为 100 毫伏（即十分之一伏特），但计算表明，这种电位产生的电场接近膜所能承受的最大电场——据计算，大于 200 毫伏的电位差可能导致介质击穿，即产生跨膜电弧。

===易化扩散和易化转运 ===

===易化扩散和易化转运 ===

[[File:Action potential ion sizes.svg.png|thumb|Despite the small differences in their radii,<ref name=":6">''CRC Handbook of Chemistry and Physics'', 83rd edition, {{ISBN|0-8493-0483-0}}, pp. 12–14 to 12–16.</ref> ions rarely go through the "wrong" channel. For example, sodium or calcium ions rarely pass through a potassium channel.

[[File:Action potential ion sizes.svg.png|thumb|Despite the small differences in their radii,<ref name=":6">''CRC Handbook of Chemistry and Physics'', 83rd edition, {{ISBN|0-8493-0483-0}}, pp. 12–14 to 12–16.</ref> ions rarely go through the "wrong" channel. For example, sodium or calcium ions rarely pass through a potassium channel.

尽管它们的半径有很小的差别,<ref name=":6" /><nowiki>，化学和物理的CRC手册，第83版，pp。12-14呼叫12-16。离子很少通过错误的通道。例如，钠离子或钙离子很少通过钾离子通道。| alt = 7个球半径与一价锂、钠、钾、铷、铯离子（分别为0.76、1.02、1.38、1.52和1.67 å）、二价钙离子（1.00 å）和一价氯离子（1.81 å）的半径成正比。</nowiki>|链接=Special:FilePath/Action_potential_ion_sizes.svg.png]]

尽管它们的半径有很小的差别,<ref name=":6" /><nowiki>，化学和物理的离子很少通过错误的通道。例如，钠离子或钙离子很少通过钾离子通道。| alt = 7个球半径与一价锂、钠、钾、铷、铯离子（分别为0.76、1.02、1.38、1.52和1.67 å）、二价钙离子（1.00 å）和一价氯离子（1.81 å）的半径成正比。</nowiki>|链接=Special:FilePath/Action_potential_ion_sizes.svg.png]]

[[Ion channel]]s are [[integral membrane protein]]s with a pore through which ions can travel between extracellular space and cell interior. Most channels are specific （selective） for one ion; for example, most potassium channels are characterized by 1000:1 selectivity ratio for potassium over sodium, though potassium and sodium ions have the same charge and differ only slightly in their radius. The channel pore is typically so small that ions must pass through it in single-file order.<ref name="eisenman_theory">{{cite book | author = Eisenman G | year = 1961 | chapter = On the elementary atomic origin of equilibrium ionic specificity | title = Symposium on Membrane Transport and Metabolism | editor = A Kleinzeller |editor2=A Kotyk | publisher = Academic Press | location = New York | pages = 163–79}}{{cite book | author = Eisenman G | year = 1965 | chapter = Some elementary factors involved in specific ion permeation | title = Proc. 23rd Int. Congr. Physiol. Sci., Tokyo | publisher = Excerta Med. Found. | location = Amsterdam | pages = 489–506}}<br />* {{cite journal |vauthors=Diamond JM, Wright EM | year = 1969 | title = Biological membranes: the physical basis of ion and nonekectrolyte selectivity | journal = Annual Review of Physiology | volume = 31 | pages = 581–646 | doi = 10.1146/annurev.ph.31.030169.003053 | pmid = 4885777}}</ref>    Channel pores can be either open or closed for ion passage, although a number of channels demonstrate various sub-conductance levels. When a channel is open, ions permeate through the channel pore down the transmembrane concentration gradient for that particular ion. Rate of ionic flow through the channel, i.e. single-channel current amplitude, is determined by the maximum channel conductance and electrochemical driving force for that ion, which is the difference between the instantaneous value of the membrane potential and the value of the [[reversal potential]].<ref name="junge_33_37">Junge, pp. 33–37.</ref>

[[Ion channel]]s are [[integral membrane protein]]s with a pore through which ions can travel between extracellular space and cell interior. Most channels are specific （selective） for one ion; for example, most potassium channels are characterized by 1000:1 selectivity ratio for potassium over sodium, though potassium and sodium ions have the same charge and differ only slightly in their radius. The channel pore is typically so small that ions must pass through it in single-file order.<ref name="eisenman_theory">{{cite book | author = Eisenman G | year = 1961 | chapter = On the elementary atomic origin of equilibrium ionic specificity | title = Symposium on Membrane Transport and Metabolism | editor = A Kleinzeller |editor2=A Kotyk | publisher = Academic Press | location = New York | pages = 163–79}}{{cite book | author = Eisenman G | year = 1965 | chapter = Some elementary factors involved in specific ion permeation | title = Proc. 23rd Int. Congr. Physiol. Sci., Tokyo | publisher = Excerta Med. Found. | location = Amsterdam | pages = 489–506}}<br />* {{cite journal |vauthors=Diamond JM, Wright EM | year = 1969 | title = Biological membranes: the physical basis of ion and nonekectrolyte selectivity | journal = Annual Review of Physiology | volume = 31 | pages = 581–646 | doi = 10.1146/annurev.ph.31.030169.003053 | pmid = 4885777}}</ref>    Channel pores can be either open or closed for ion passage, although a number of channels demonstrate various sub-conductance levels. When a channel is open, ions permeate through the channel pore down the transmembrane concentration gradient for that particular ion. Rate of ionic flow through the channel, i.e. single-channel current amplitude, is determined by the maximum channel conductance and electrochemical driving force for that ion, which is the difference between the instantaneous value of the membrane potential and the value of the [[reversal potential]].<ref name="junge_33_37">Junge, pp. 33–37.</ref>

一个特定离子的平衡电位通常用记号 ''E''_ion 来表示。任何离子的平衡电位都可以用能斯特方程来计算。<ref name="nernst" /> 例如，钾离子的逆转电位如下:

一个特定离子的平衡电位通常用记号 ''E''_ion 来表示。任何离子的平衡电位都可以用能斯特方程来计算。<ref name="nernst" /> 例如，钾离子的逆转电位如下:

:<math> E_{eq,K^+} = \frac{RT}{zF} \ln \frac{[K^+]_{o}}{[K^+]_{i}} , </math>

:<math> E_{eq,K^+} = \frac{RT}{zF} \ln \frac{[K^+]_{o}}{[K^+]_{i}} , </math>

 

: <nowiki>E_{eq,K^+} = \frac{RT}{zF} \ln \frac{[K^+]_{o}}{[K^+]_{i}} ,</nowiki>

: <nowiki>E_{eq,K^+} = \frac{RT}{zF} \ln \frac{[K^+]_{o}}{[K^+]_{i}} ,</nowiki>

细胞兴奋性（Cell excitability）是各种组织中的细胞反应所必需的细胞膜电位变化。细胞兴奋性是早期胚胎发生过程中诱导的一种特性 <ref name=":10">{{Cite journal|last=Tosti|first=Elisabetta|date=2010-06-28|title=Dynamic roles of ion currents in early development|journal=Molecular Reproduction and Development|volume=77|issue=10|pages=856–867|doi=10.1002/mrd.21215|pmid=20586098|s2cid=38314187|issn=1040-452X|doi-access=free}}</ref>。细胞兴奋性也被定义为引起反应的容易程度 <ref name=":11">{{Cite journal|last1=Boyet|first1=M.R.|last2=Jewell|first2=B.R.|date=1981|title=Analysis of the effects of changes in rate and rhythm upon electrical activity in the heart|journal=Progress in Biophysics and Molecular Biology|volume=36|issue=1|pages=1–52|doi=10.1016/0079-6107(81)90003-1|pmid=7001542|issn=0079-6107|doi-access=free}}</ref> 。静息电位和阈电位是细胞兴奋性的基础，这些过程是细胞剂量电位和动作电位产生的基础。

细胞兴奋性（Cell excitability）是各种组织中的细胞反应所必需的细胞膜电位变化。细胞兴奋性是早期胚胎发生过程中诱导的一种特性 <ref name=":10">{{Cite journal|last=Tosti|first=Elisabetta|date=2010-06-28|title=Dynamic roles of ion currents in early development|journal=Molecular Reproduction and Development|volume=77|issue=10|pages=856–867|doi=10.1002/mrd.21215|pmid=20586098|s2cid=38314187|issn=1040-452X|doi-access=free}}</ref>。细胞兴奋性也被定义为引起反应的容易程度 <ref name=":11">{{Cite journal|last1=Boyet|first1=M.R.|last2=Jewell|first2=B.R.|date=1981|title=Analysis of the effects of changes in rate and rhythm upon electrical activity in the heart|journal=Progress in Biophysics and Molecular Biology|volume=36|issue=1|pages=1–52|doi=10.1016/0079-6107(81)90003-1|pmid=7001542|issn=0079-6107|doi-access=free}}</ref> 。静息电位和阈电位是细胞兴奋性的基础，这些过程是细胞剂量电位和动作电位产生的基础。

细胞兴奋性最重要的调节因子是细胞外电解质浓度（即 Na⁺, K⁺, [[Calcium metabolism|Ca²⁺]], Cl⁻, [[Magnesium in biology|Mg²⁺]]）及其相关蛋白。调节细胞兴奋性的重要蛋白质是电压门控离子通道、离子转运蛋白（如钠钾 ATP 酶、镁转运蛋白、酸碱转运蛋白）、膜受体和超极化激活的环核苷酸门控通道 <ref name=":12">{{Cite journal|last1=Spinelli|first1=Valentina|last2=Sartiani|first2=Laura|last3=Mugelli|first3=Alessandro|last4=Romanelli|first4=Maria Novella|last5=Cerbai|first5=Elisabetta|date=2018|title=Hyperpolarization-activated cyclic-nucleotide-gated channels: pathophysiological, developmental, and pharmacological insights into their function in cellular excitability|journal=Canadian Journal of Physiology and Pharmacology|volume=96|issue=10|pages=977–984|doi=10.1139/cjpp-2018-0115|pmid=29969572|issn=0008-4212|hdl=1807/90084|hdl-access=free}}</ref>。例如，钾离子通道和钙敏感受体是神经元、心肌细胞和星形胶质细胞等其他兴奋性细胞的兴奋性的重要调节因子<ref name=":13">{{Cite journal|last1=Jones|first1=Brian L.|last2=Smith|first2=Stephen M.|date=2016-03-30|title=Calcium-Sensing Receptor: A Key Target for Extracellular Calcium Signaling in Neurons|journal=Frontiers in Physiology|volume=7|page=116|doi=10.3389/fphys.2016.00116|pmid=27065884|pmc=4811949|issn=1664-042X|doi-access=free}}</ref> 。钙离子也是可兴奋细胞信号转导中最重要的第二信使。突触受体的激活产生神经元兴奋性的长期改变 <ref name=":14">{{Cite journal|last1=Debanne|first1=Dominique|last2=Inglebert|first2=Yanis|last3=Russier|first3=Michaël|date=2019|title=Plasticity of intrinsic neuronal excitability|journal=Current Opinion in Neurobiology|language=en|volume=54|pages=73–82|doi=10.1016/j.conb.2018.09.001|pmid=30243042|s2cid=52812190|url=https://hal-amu.archives-ouvertes.fr/hal-01963474/file/Debannne-Russier-2019.pdf}}</ref>。甲状腺激素、肾上腺激素和其他激素也调节细胞的兴奋性，例如，孕酮和雌激素调节子宫平滑肌细胞的兴奋性。

细胞兴奋性最重要的调节因子是细胞外电解质浓度（即 Na⁺, K⁺, [[Calcium metabolism|Ca²⁺]], Cl⁻, [[Magnesium in biology|Mg²⁺]]）及其相关蛋白。调节细胞兴奋性的重要蛋白质是电压门控离子通道、离子转运蛋白（如钠钾 ATP 酶、镁转运蛋白、酸碱转运蛋白）、膜受体和超极化激活的环核苷酸门控通道 <ref name=":12">{{Cite journal|last1=Spinelli|first1=Valentina|last2=Sartiani|first2=Laura|last3=Mugelli|first3=Alessandro|last4=Romanelli|first4=Maria Novella|last5=Cerbai|first5=Elisabetta|date=2018|title=Hyperpolarization-activated cyclic-nucleotide-gated channels: pathophysiological, developmental, and pharmacological insights into their function in cellular excitability|journal=Canadian Journal of Physiology and Pharmacology|volume=96|issue=10|pages=977–984|doi=10.1139/cjpp-2018-0115|pmid=29969572|issn=0008-4212|hdl=1807/90084|hdl-access=free}}</ref>。例如，钾离子通道和钙敏感受体是神经元、心肌细胞和星形胶质细胞等其他兴奋性细胞的兴奋性的重要调节因子<ref name=":13">{{Cite journal|last1=Jones|first1=Brian L.|last2=Smith|first2=Stephen M.|date=2016-03-30|title=Calcium-Sensing Receptor: A Key Target for Extracellular Calcium Signaling in Neurons|journal=Frontiers in Physiology|volume=7|page=116|doi=10.3389/fphys.2016.00116|pmid=27065884|pmc=4811949|issn=1664-042X|doi-access=free}}</ref> 。钙离子也是兴奋性细胞信号转导中最重要的第二信使。突触受体的激活产生神经元兴奋性的长期改变 <ref name=":14">{{Cite journal|last1=Debanne|first1=Dominique|last2=Inglebert|first2=Yanis|last3=Russier|first3=Michaël|date=2019|title=Plasticity of intrinsic neuronal excitability|journal=Current Opinion in Neurobiology|language=en|volume=54|pages=73–82|doi=10.1016/j.conb.2018.09.001|pmid=30243042|s2cid=52812190|url=https://hal-amu.archives-ouvertes.fr/hal-01963474/file/Debannne-Russier-2019.pdf}}</ref>。甲状腺激素、肾上腺激素和其他激素也调节细胞的兴奋性，例如，孕酮和雌激素调节子宫平滑肌细胞的兴奋性。

Many cell types are considered to have an excitable membrane. Excitable cells are neurons, myocytes （cardiac, skeletal, [[Smooth muscle|smooth]]）, vascular [[Endothelium|endothelial cells]], [[pericyte]]s, [[juxtaglomerular cell]]s, [[Interstitial cell of Cajal|interstitial cells of Cajal]], many types of [[Epithelium|epithelial cells]] （e.g. [[beta cell]]s, [[alpha cell]]s, [[delta cell]]s, [[enteroendocrine cell]]s, [[Neuroendocrine_cell#Pulmonary_neuroendocrine_cells|pulmonary neuroendocrine cells]], [[pinealocyte]]s）, [[glia]]l cells （e.g. astrocytes）, [[mechanoreceptor]] cells （e.g. [[hair cell]]s and [[Merkel cell]]s）, [[chemoreceptor]] cells （e.g. [[glomus cell]]s, [[taste receptor]]s）, some [[plant cells]] and possibly [[White blood cell|immune cells]].<ref name=":15">{{Cite journal|last1=Davenport|first1=Bennett|last2=Li|first2=Yuan|last3=Heizer|first3=Justin W.|last4=Schmitz|first4=Carsten|last5=Perraud|first5=Anne-Laure|date=2015-07-23|title=Signature Channels of Excitability no More: L-Type Channels in Immune Cells|journal=Frontiers in Immunology|volume=6|page=375|doi=10.3389/fimmu.2015.00375|pmid=26257741|pmc=4512153|issn=1664-3224|doi-access=free}}</ref> Astrocytes display a form of non-electrical excitability based on intracellular calcium variations related to the expression of several receptors through which they can detect the synaptic signal. In neurons, there are different membrane properties in some portions of the cell, for example, dendritic excitability endows neurons with the capacity for coincidence detection of spatially separated inputs.<ref name=":16">{{Cite journal|last=Sakmann|first=Bert|date=2017-04-21|title=From single cells and single columns to cortical networks: dendritic excitability, coincidence detection and synaptic transmission in brain slices and brains|journal=Experimental Physiology|volume=102|issue=5|pages=489–521|doi=10.1113/ep085776|pmid=28139019|pmc=5435930|issn=0958-0670|doi-access=free}}</ref>

Many cell types are considered to have an excitable membrane. Excitable cells are neurons, myocytes （cardiac, skeletal, [[Smooth muscle|smooth]]）, vascular [[Endothelium|endothelial cells]], [[pericyte]]s, [[juxtaglomerular cell]]s, [[Interstitial cell of Cajal|interstitial cells of Cajal]], many types of [[Epithelium|epithelial cells]] （e.g. [[beta cell]]s, [[alpha cell]]s, [[delta cell]]s, [[enteroendocrine cell]]s, [[Neuroendocrine_cell#Pulmonary_neuroendocrine_cells|pulmonary neuroendocrine cells]], [[pinealocyte]]s）, [[glia]]l cells （e.g. astrocytes）, [[mechanoreceptor]] cells （e.g. [[hair cell]]s and [[Merkel cell]]s）, [[chemoreceptor]] cells （e.g. [[glomus cell]]s, [[taste receptor]]s）, some [[plant cells]] and possibly [[White blood cell|immune cells]].<ref name=":15">{{Cite journal|last1=Davenport|first1=Bennett|last2=Li|first2=Yuan|last3=Heizer|first3=Justin W.|last4=Schmitz|first4=Carsten|last5=Perraud|first5=Anne-Laure|date=2015-07-23|title=Signature Channels of Excitability no More: L-Type Channels in Immune Cells|journal=Frontiers in Immunology|volume=6|page=375|doi=10.3389/fimmu.2015.00375|pmid=26257741|pmc=4512153|issn=1664-3224|doi-access=free}}</ref> Astrocytes display a form of non-electrical excitability based on intracellular calcium variations related to the expression of several receptors through which they can detect the synaptic signal. In neurons, there are different membrane properties in some portions of the cell, for example, dendritic excitability endows neurons with the capacity for coincidence detection of spatially separated inputs.<ref name=":16">{{Cite journal|last=Sakmann|first=Bert|date=2017-04-21|title=From single cells and single columns to cortical networks: dendritic excitability, coincidence detection and synaptic transmission in brain slices and brains|journal=Experimental Physiology|volume=102|issue=5|pages=489–521|doi=10.1113/ep085776|pmid=28139019|pmc=5435930|issn=0958-0670|doi-access=free}}</ref>

The interactions that generate the resting potential are modeled by the [[Goldman equation]].<ref name="Goldman">Purves ''et al.'', pp. 32&ndash;33; [[Theodore Holmes Bullock|Bullock]], Orkand, and Grinnell, pp. 138&ndash;140; Schmidt-Nielsen, pp. 480; Junge, pp. 35&ndash;37</ref>  This is similar in form to the Nernst equation shown above, in that it is based on the charges of the ions in question, as well as the difference between their inside and outside concentrations. However, it also takes into consideration the relative permeability of the plasma membrane to each ion in question.

The interactions that generate the resting potential are modeled by the [[Goldman equation]].<ref name="Goldman">Purves ''et al.'', pp. 32&ndash;33; [[Theodore Holmes Bullock|Bullock]], Orkand, and Grinnell, pp. 138&ndash;140; Schmidt-Nielsen, pp. 480; Junge, pp. 35&ndash;37</ref>  This is similar in form to the Nernst equation shown above, in that it is based on the charges of the ions in question, as well as the difference between their inside and outside concentrations. However, it also takes into consideration the relative permeability of the plasma membrane to each ion in question.

戈德曼方程（Goldman equation）可以模拟产生静息电位的相互作用。<ref name="Goldman" /> 形式上类似于上述的能斯特方程，也是基于有关离子的电荷及其细胞内外浓度差而建立的。当然，它也考虑了质膜对每种离子的相对渗透性。

戈德曼方程可以模拟产生静息电位的相互作用。<ref name="Goldman" /> 形式上类似于上述的能斯特方程，也是基于有关离子的电荷及其细胞内外浓度差而建立的。当然，它也考虑了质膜对每种离子的相对渗透性。

:<math>

:<math>

The three ions that appear in this equation are potassium （K⁺）, sodium （Na⁺）, and chloride （Cl^&minus;）. Calcium is omitted, but can be added to deal with situations in which it plays a significant role.<ref name="goldman_calcium">{{cite journal | author = Spangler SG | year = 1972 | title = Expansion of the constant field equation to include both divalent and monovalent ions | journal = Alabama Journal of Medical Sciences | volume = 9 | pages = 218–23|pmid=5045041 | issue = 2 }}</ref>  Being an anion, the chloride terms are treated differently from the cation terms; the intracellular concentration is in the numerator, and the extracellular concentration in the denominator, which is reversed from the cation terms. ''P''_i stands for the relative permeability of the ion type i.

The three ions that appear in this equation are potassium （K⁺）, sodium （Na⁺）, and chloride （Cl^&minus;）. Calcium is omitted, but can be added to deal with situations in which it plays a significant role.<ref name="goldman_calcium">{{cite journal | author = Spangler SG | year = 1972 | title = Expansion of the constant field equation to include both divalent and monovalent ions | journal = Alabama Journal of Medical Sciences | volume = 9 | pages = 218–23|pmid=5045041 | issue = 2 }}</ref>  Being an anion, the chloride terms are treated differently from the cation terms; the intracellular concentration is in the numerator, and the extracellular concentration in the denominator, which is reversed from the cation terms. ''P''_i stands for the relative permeability of the ion type i.

在这个方程式中出现的三个离子是钾（K⁺）（Na⁺）和（Cl^&minus;）。钙是省略的，但可以添加到处理的情况下，它发挥了重要的作用le.<ref name="goldman_calcium" />  。作为一个阴离子，氯离子项处理不同于阳离子项; 细胞内浓度是在分子，胞外浓度在分母，这是反向阳离子项。Pi 代表离子类型 i 的相对渗透率。

在这个方程式中出现的三个离子是钾（K⁺）、（Na⁺）和（Cl^&minus;）。钙是省略的，但可以添加到处理的情况下，它发挥了重要的作用。<ref name="goldman_calcium" /> 作为一个阴离子，氯离子项处理不同于阳离子项；细胞内浓度是在分子，胞外浓度在分母，这与阳离子项是反过来的。''P''_i 代表离子类型 i 的相对渗透率。

In essence, the Goldman formula expresses the membrane potential as a weighted average of the reversal potentials for the individual ion types, weighted by permeability. （Although the membrane potential changes about 100 mV during an action potential, the concentrations of ions inside and outside the cell do not change significantly. They remain close to their respective concentrations when then membrane is at resting potential.） In most animal cells, the permeability to potassium is much higher in the resting state than the permeability to sodium.  As a consequence, the resting potential is usually close to the potassium reversal potential.<ref name="resting_potential">Purves ''et al.'', p. 34; [[Theodore Holmes Bullock|Bullock]], Orkand, and Grinnell, p. 134; [[Knut Schmidt-Nielsen|Schmidt-Nielsen]], pp. 478&ndash;480.</ref><ref name=":18">Purves ''et al.'', pp. 33&ndash;36; [[Theodore Holmes Bullock|Bullock]], Orkand, and Grinnell, p. 131.</ref>  The permeability to chloride can be high enough to be significant, but, unlike the other ions, chloride is not actively pumped, and therefore equilibrates at a reversal potential very close to the resting potential determined by the other ions.

In essence, the Goldman formula expresses the membrane potential as a weighted average of the reversal potentials for the individual ion types, weighted by permeability. （Although the membrane potential changes about 100 mV during an action potential, the concentrations of ions inside and outside the cell do not change significantly. They remain close to their respective concentrations when then membrane is at resting potential.） In most animal cells, the permeability to potassium is much higher in the resting state than the permeability to sodium.  As a consequence, the resting potential is usually close to the potassium reversal potential.<ref name="resting_potential">Purves ''et al.'', p. 34; [[Theodore Holmes Bullock|Bullock]], Orkand, and Grinnell, p. 134; [[Knut Schmidt-Nielsen|Schmidt-Nielsen]], pp. 478&ndash;480.</ref><ref name=":18">Purves ''et al.'', pp. 33&ndash;36; [[Theodore Holmes Bullock|Bullock]], Orkand, and Grinnell, p. 131.</ref>  The permeability to chloride can be high enough to be significant, but, unlike the other ions, chloride is not actively pumped, and therefore equilibrates at a reversal potential very close to the resting potential determined by the other ions.

从本质上讲，高盛公式将膜电位表示为单个离子类型的逆转势的加权平均数，通过渗透率加权。（虽然膜电位在动作电位期间会发生100mv 左右的变化，但细胞内外的离子浓度不会发生显著变化。当膜处于静息电位时，它们仍然接近各自的浓度。）在大多数动物细胞中，静息状态下钾的通透性比钠的通透性高得多。As a consequence, the resting potential is usually close to the potassium reversal potential.Purves et al., p. 34; Bullock, Orkand, and Grinnell, p. 134; Schmidt-Nielsen, pp.478-480. Purves et al. ，pp.33-36; 布洛克，Orkand 和格林内尔，p. 131。但是，与其他离子不同的是，氯离子没有被主动泵入，因此平衡的逆转电位非常接近由其他离子决定的静息电位。l.<ref name="resting_potential" /><ref name=":18" />  

从本质上讲，戈德曼公式将膜电位表示为单个离子类型的逆转电位的渗透率加权平均。（虽然膜电位在动作电位期间会发生100 mV 左右的变化，但细胞内外的离子浓度不会发生显著变化，仍然接近膜处于静息电位时各自的浓度。）在大多数动物细胞中，静息状态下钾的通透性比钠的通透性高得多。但是，与其他离子不同的是，氯离子没有被主动泵入，因此平衡的逆转电位非常接近由其他离子决定的静息电位。<ref name="resting_potential" /><ref name=":18" />  

Values of resting membrane potential in most animal cells usually vary between the potassium reversal potential （usually around -80 mV） and around -40 mV. The resting potential in excitable cells （capable of producing action potentials） is usually near -60 mV—more depolarized voltages would lead to spontaneous generation of action potentials. Immature or undifferentiated cells show highly variable values of resting voltage, usually significantly more positive than in differentiated cells.<ref name="Magnuson DS et al., 1995">{{cite journal | doi = 10.1016/0165-3806(94)00166-W |vauthors=Magnuson DS, Morassutti DJ, Staines WA, McBurney MW, Marshall KC | date =  Jan 14, 1995| title = In vivo electrophysiological maturation of neurons derived from a multipotent precursor (embryonal carcinoma) cell line | journal = Developmental Brain Research| volume = 84|issue = 1| pages = 130–41 | pmid = 7720212}}</ref> In such cells, the resting potential value correlates with the degree of differentiation: undifferentiated cells in some cases may not show any transmembrane voltage difference at all.

Values of resting membrane potential in most animal cells usually vary between the potassium reversal potential （usually around -80 mV） and around -40 mV. The resting potential in excitable cells （capable of producing action potentials） is usually near -60 mV—more depolarized voltages would lead to spontaneous generation of action potentials. Immature or undifferentiated cells show highly variable values of resting voltage, usually significantly more positive than in differentiated cells.<ref name="Magnuson DS et al., 1995">{{cite journal | doi = 10.1016/0165-3806(94)00166-W |vauthors=Magnuson DS, Morassutti DJ, Staines WA, McBurney MW, Marshall KC | date =  Jan 14, 1995| title = In vivo electrophysiological maturation of neurons derived from a multipotent precursor (embryonal carcinoma) cell line | journal = Developmental Brain Research| volume = 84|issue = 1| pages = 130–41 | pmid = 7720212}}</ref> In such cells, the resting potential value correlates with the degree of differentiation: undifferentiated cells in some cases may not show any transmembrane voltage difference at all.

在大多数动物细胞中，静息膜电位的数值通常在逆转电位（通常在 -80 mV）和 -40 mV 之间变化。可兴奋细胞（能够产生动作电位）的静息电位通常接近60mv ー更多的去极化电压会导致动作电位的自然发生。未成熟或未分化细胞的静息电压变化很大，通常明显高于已分化的细胞.<ref name="Magnuson DS et al., 1995" /> 。在这些细胞中，静息电位值与分化程度相关: 在某些情况下未分化的细胞可能根本没有任何跨膜电压差。

在大多数动物细胞中，静息膜电位的数值通常在逆转电位（通常在 -80 mV）和 -40 mV 之间变化。（能够产生动作电位的）兴奋性细胞的静息电位通常接近 -60 mV ——更多的去极化电位会导致动作电位的自然发生。未成熟或未分化细胞的静息电位变化很大，通常明显高于已分化的细胞.<ref name="Magnuson DS et al., 1995" /> 。在这些细胞中，静息电位值与分化程度相关: 在某些情况下未分化的细胞可能根本没有任何跨膜电位差。

Maintenance of the resting potential can be metabolically costly for a cell because of its requirement for active pumping of ions to counteract losses due to leakage channels. The cost is highest when the cell function requires an especially depolarized value of membrane voltage. For example, the resting potential in daylight-adapted [[Calliphoridae|blowfly]] （''Calliphora vicina''） [[Simple eyes in invertebrates|photoreceptor]]s can be as high as -30 mV.<ref name="Juusola M et al., 1994">{{cite journal | doi = 10.1085/jgp.104.3.593 |vauthors=Juusola M, Kouvalainen E, Järvilehto M, Weckström M | date =  Sep 1994| title = Contrast gain, signal-to-noise ratio, and linearity in light-adapted blowfly photoreceptors| journal = J Gen Physiol| volume = 104| issue = 3| pages = 593–621|pmid = 7807062 | pmc = 2229225}}</ref> This elevated membrane potential allows the cells to respond very rapidly to visual inputs; the cost is that maintenance of the resting potential may consume more than 20% of overall cellular [[Adenosine triphosphate|ATP]].<ref name="Laughlin SB et al., 2008">{{cite journal |vauthors=Laughlin SB, de Ruyter van Steveninck RR, Anderson JC | date = May 1998| title = The metabolic cost of neural information| journal =  Nat. Neurosci.| volume = 1| issue = 1| pages = 36–41|pmid = 10195106 | doi = 10.1038/236| s2cid = 204995437}}</ref>

Maintenance of the resting potential can be metabolically costly for a cell because of its requirement for active pumping of ions to counteract losses due to leakage channels. The cost is highest when the cell function requires an especially depolarized value of membrane voltage. For example, the resting potential in daylight-adapted [[Calliphoridae|blowfly]] （''Calliphora vicina''） [[Simple eyes in invertebrates|photoreceptor]]s can be as high as -30 mV.<ref name="Juusola M et al., 1994">{{cite journal | doi = 10.1085/jgp.104.3.593 |vauthors=Juusola M, Kouvalainen E, Järvilehto M, Weckström M | date =  Sep 1994| title = Contrast gain, signal-to-noise ratio, and linearity in light-adapted blowfly photoreceptors| journal = J Gen Physiol| volume = 104| issue = 3| pages = 593–621|pmid = 7807062 | pmc = 2229225}}</ref> This elevated membrane potential allows the cells to respond very rapidly to visual inputs; the cost is that maintenance of the resting potential may consume more than 20% of overall cellular [[Adenosine triphosphate|ATP]].<ref name="Laughlin SB et al., 2008">{{cite journal |vauthors=Laughlin SB, de Ruyter van Steveninck RR, Anderson JC | date = May 1998| title = The metabolic cost of neural information| journal =  Nat. Neurosci.| volume = 1| issue = 1| pages = 36–41|pmid = 10195106 | doi = 10.1038/236| s2cid = 204995437}}</ref>

As can be derived from the [[Goldman equation]] shown above, the effect of increasing the permeability of a membrane to a particular type of ion shifts the membrane potential toward the reversal potential for that ion. Thus, opening Na⁺ channels shifts the membrane potential toward the Na⁺ reversal potential, which is usually around +100 mV. Likewise, opening K⁺ channels shifts the membrane potential toward about –90 mV, and opening Cl⁻ channels shifts it toward about –70 mV （resting potential of most membranes）. Thus, Na⁺ channels shift the membrane potential in a positive direction, K⁺ channels shift it in a negative direction （except when the membrane is hyperpolarized to a value more negative than the K⁺ reversal potential）, and Cl⁻ channels tend to shift it towards the resting potential.

As can be derived from the [[Goldman equation]] shown above, the effect of increasing the permeability of a membrane to a particular type of ion shifts the membrane potential toward the reversal potential for that ion. Thus, opening Na⁺ channels shifts the membrane potential toward the Na⁺ reversal potential, which is usually around +100 mV. Likewise, opening K⁺ channels shifts the membrane potential toward about –90 mV, and opening Cl⁻ channels shifts it toward about –70 mV （resting potential of most membranes）. Thus, Na⁺ channels shift the membrane potential in a positive direction, K⁺ channels shift it in a negative direction （except when the membrane is hyperpolarized to a value more negative than the K⁺ reversal potential）, and Cl⁻ channels tend to shift it towards the resting potential.

正如我们从上面的戈德曼方程中得出的结论，增加膜的渗透性对于特定类型离子的影响会使膜电位向逆转电位的方向移动。因此，开放的钠离子通道将膜电位向钠离子逆转电位转移，通常在 + 100 mV 左右。同样，开放 k + 通道使膜电位向大约 -90 mV 的方向移动，开放 Cl 通道使其向大约 -70 mV 的方向移动（大多数膜的静息电位）。因此，Na + 通道使膜电位向正方向移动，k + 通道使其向负方向移动（除非膜超极化到比 k + 逆转电位更负的程度） ，而 Cl-通道则倾向于使其向静息电位方向移动。

正如我们从上面的戈德曼方程中得出的结论，增加膜的渗透性对于特定类型离子的影响会使膜电位向逆转电位的方向移动。因此，开放的钠离子通道将膜电位向钠离子逆转电位转移，通常在 + 100 mV 左右。同样，开放 K⁺  k + 通道使膜电位向大约 -90 mV 的方向移动，开放 Cl⁻ 通道使其向大约 -70 mV 的方向移动（大多数膜的静息电位）。因此， Na⁺ Na + 通道使膜电位向正方向移动， K⁺ k + 通道使其向负方向移动（除非膜超极化到比 K⁺ k + 逆转电位更负的程度） ，而 Cl⁻  Cl-通道则倾向于使其向静息电位方向移动。

[[File:IPSPsummation.JPG|thumb|center|500px|Graph displaying an EPSP, an IPSP, and the summation of an EPSP and an IPSP显示 EPSP、 IPSP、 EPSP 和 IPSP |链接=Special:FilePath/IPSPsummation.JPG]]

[[File:IPSPsummation.JPG|thumb|center|500px|Graph displaying an EPSP, an IPSP, and the summation of an EPSP and an IPSP显示 EPSP、 IPSP、 EPSP 和 IPSP |链接=Special:FilePath/IPSPsummation.JPG]]