Neuron resting potential!!

[StayingSteady]

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hey, I was wondering if someone could briefly explain what causes the resting membrane potential (-70 mV) in a neuron. I couldn't really understand what Kaplan was getting at... they were mentioning the Na+/K+ pump, the selective permeability of the membrane to K+, the electrochemical gradient, etc etc. What exactly maintains this potential? And also, when exactly does the Na/K pump come into play (I'm thinking it's after the hyperpolarization, but I'm not entirely sure)?

 

[capn jazz]

The membrane is, at rest, pockmarked with K+ "leaky" channels - channels through which K+ can passively diffuse, leaving being a net negative charge in the inside versus the outside.

The Na+/K+ pump maintains the resting potential as well, pumping Na+ ions out and K+ in (this maintains a concentration gradient allowing K+ to flow out through the leaky channels). It also needs a low concentration of Na+ ions inside the neuron to allow for the huge influx at the start of an action potential.

The Nernst potential of K+ is -80 mV and the resting potential is -70 mV because of the selective permeability (leaky channels) to K+.