I understand that the repolarization is because some K+ chanels are opened with the action potential. But whats happens with the sodium chemical gradient that is needed for a new action potential? Are there further Na-K pumps in the axon membrane?

  • $\begingroup$ Na+/K+ pumps are extremely ubiquitous. I recall reading that 1/3rd of an average cell's energy budget goes to maintaining that gradient, with neurons bringing this up to 2/3rds. $\endgroup$ – forest Mar 22 '18 at 21:02

Yes, there are Na-K pumps all over.

However, it is important to recognize that ion concentrations change very little during action potentials. The change in membrane potential is due to changes in ion conductances, very few ions actually flow. It is still necessary to maintain concentration gradients over many many action potentials, but the change in concentrations during the course of a single action potential is negligible.

  • $\begingroup$ Probably too late to ask but I'd love an explanation for the downvote. $\endgroup$ – Bryan Krause Nov 22 '17 at 21:12
  • $\begingroup$ No not too late. Just a lack of sources. Also the fact it's a four liner makes it a bit of a content less answer. Ping me once updated. Happy to upvote. $\endgroup$ – AliceD Nov 23 '17 at 6:55
  • $\begingroup$ Heck, the question is quite poor too. Poor question, mediocre answer. I'll remove the downvote. $\endgroup$ – AliceD Mar 22 '18 at 21:39
  • 1
    $\begingroup$ @AliceD If you want to merge it with biology.stackexchange.com/questions/57064/… that could be done, I like my answer better there anyways. Might need to make a new canonical answer and question to fit all those types of questions though, because there are a variety of questions people ask that deserve basically exactly the same response. $\endgroup$ – Bryan Krause Mar 22 '18 at 21:50

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