Action Potential Propagation And The Refractory Period Explained (Relative and Absolute) | Clip

[@shortfutiball7023]

thank you very much for all the graphs everything is clearer !! however there is always something that I do not understand: normally a cell must respect the principle of electroneutrality but the membrane potential of the neuron and other membranes is often negative (-70mV) So does by electroneutrality we mean that both sides (extra and intra cellular) have a neutral charge or that one side is negative and the other is positive making everything neutral? I don't know if you know what I mean thank you !

[@sciencewithtal]

That is a very good question! Cells do indeed respect the electroneutrality law, at least in the sense that the interactions between the ions are as we expect them to be (+ attracts -, + repels +). Paired with the fact that ions are unevenly distributed, this relationship leads each ionic specie to develop an electrochemical gradient, which is the force that drags ions to be at chemical and electrical equilibrium. The reason why the membrane potential of the cell is negative and uneven is that the neuron wants it to be that way and spends a lot of energy (ATP) doing so through the activity of the Na/K pumps. Hence, the resting membrane potential now allows to serve as a basis for electrical conduction because sodium ions want to enter very much and potassium ions will leave if that happens too much, which leads to the action potential. To answer your question more directly, I would say that neurons make an effort (Na/K pumps and leak channels) at not being at electric neutrality because it allows them to have a way to communicate across their bodies (action potential/depolarizations). If ever that is still unclear, I recommend maybe having a look at these two videos; you might find some enlightenment there as well: Nernst Equation And The Electrochemical Gradient Explained | Clip kzbin.info/www/bejne/qHu2e4qlqKd9nZI Goldman Equation And The Resting Membrane Potential Explained | Clip kzbin.info/www/bejne/j4CpiZ6QqpKlbq8 Let me know if there are still some concerns, and thanks a lot for the feedback!

[@shortfutiball7023]

Yes I watched them but there was always this detail that I couldn't understand! And so are neurons the only cells that don't "want" to be neutral, or are other cells the same? Thank you very much for your answer !

[@sciencewithtal]

@@shortfutiball7023 I guess that would depend on the purposes of the cell in question. Since the main purpose of neurons is to communicate and that communication requires that they are constantly in an ionic imbalance, neurons are not neutral. As far as I know, neurons are the best example of cells that do not want to be neutral but I am sure there are plenty more.

[@shortfutiball7023]

@@sciencewithtal ok thanks for the answers everything is clear now. i hope all your work on ytb will pay !

[@sciencewithtal]

@@shortfutiball7023 Thank you! Don't hesitate to ask again if ever!