Editing Resting potential (section)

{{Short description|Static membrane potential in biology}}
[[File:Sodium-potassium pump and diffusion.png|thumb|upright=1.3|The [[Sodium-potassium pump|{{chem|Na|+|/K|+}}-ATPase]], as well as effects of diffusion of the involved ions, are major mechanisms to maintain the resting potential across the membranes of animal cells.]]

The relatively static [[membrane potential]] of [[wikt:quiescence#Noun|quiescent]] cells is called the '''resting membrane potential''' (or resting voltage), as opposed to the specific dynamic electrochemical phenomena called [[action potential]] and graded [[membrane potential]]. The '''resting membrane potential''' has a value of approximately '''−70&nbsp;mV or −0.07&nbsp;V'''.<ref>{{Cite web |title=Resting Membrane Potential - Nernst - Generation |url=https://bio.libretexts.org/Courses/Lumen_Learning/Biology_for_Majors_II_(Lumen)/17%3A_Module_14-_The_Nervous_System/17.09%3A_Resting_Membrane_Potential |access-date=2024-09-18 |website=TeachMePhysiology|date=13 January 2021 }}</ref> 

Apart from the latter two, which occur in [[Membrane potential|excitable cells]] ([[neuron]]s, [[muscle]]s, and some secretory cells in [[gland]]s), membrane voltage in the majority of non-excitable cells can also undergo changes in response to environmental or intracellular stimuli. The resting potential exists due to the differences in membrane permeabilities for [[potassium]], [[sodium]], [[calcium]], and [[chloride]] [[ion]]s, which in turn result from functional activity of various [[ion channel]]s, [[ion transporter]]s, and exchangers.  Conventionally, resting membrane potential can be defined as a relatively stable, ground value of transmembrane voltage in animal and plant cells.<br />
 
Because the membrane permeability for potassium is much higher than that for other ions, and because of the strong chemical gradient for potassium, potassium ions flow from the cytosol out to the extracellular space carrying out positive charge, until their movement is balanced by build-up of negative charge on the inner surface of the membrane. Again, because of the high relative permeability for potassium, the resulting membrane potential is almost always close to the potassium [[reversal potential]]. But in order for this process to occur, a concentration gradient of potassium ions must first be set up. This work is done by the [[ion transporter|ion pumps/transporters]] and/or exchangers and generally is powered by [[Adenosine triphosphate|ATP]].{{cn|date=May 2025}}

In the case of the resting membrane potential across an animal cell's [[cell membrane|plasma membrane]], potassium (and sodium) gradients are established by the [[Na+/K+-ATPase|Na<sup>+</sup>/K<sup>+</sup>-ATPase]] (sodium-potassium pump) which transports 2 potassium ions inside and 3 sodium ions outside at the cost of 1 ATP molecule. In other cases, for example, a membrane potential may be established by acidification of the inside of a membranous compartment (such as the proton pump that generates membrane potential across [[synaptic vesicle]] membranes).{{Citation needed|date=January 2009}}