In a neutral electrical potential?

Question

In order for there to be a neutral electrical potential does that mean the amount of cations and anions is equal to the amount of cations and anions on other side? Even if there is a higher concentration of that specific ion?

 

Answer 1

Without any extracellular influence, the resting membrane potential will remain steady because of the ion leakage channels and pumping channels. The stimulus for opening other channels can be either a neurotransmitter or a concentration gradient that increases the resting membrane charge from -70mV to -55mV. Because Na+ ions have a higher concentration outside the cell membrane by a factor of 10, an increase in extracellular concentration (resulting in a high concentration gradient) will drive the resting charge of the membrane to change and trigger an action potential. As the resting charge is around -70mV and a higher concentration of anions in the cytosol and membrane (in the form of phosphate ions and proteins with positive charge), a higher concentration of cations immediately outside the membrane will open Na+ channels because of the electrochemical gradient. The rush of Na+ into the cell causes the membrane potential to become less negative. The membrane potential becoming less negative is what is called depolarization. The change of membrane potential up to +30mV opens other voltage gated channels to open for intracellular K+ to exit through the membrane and actually overshoot (hyperrepolarization) in order to restore a balanced concentration. The slow closing of the K+ channels are responsible for the hyperrepolarization but, after closing, the leakage channels and the close to -70mV membrane charge allow for redistribution and return of the resting potential.