|MadSci Network: Neuroscience|
In neurones, the active transport of Na+ ions out of the axon and K+ ions into the axon by the sodium-potassium pump is known as secondary active transport. I have read that secondary active transport involves one type of the 2 molecules moving along its electrochemical gradient with the other moving against its electrochemical gradient. I however always thought both Na+ ions and K+ ions moved against their electrochemical gradients during the restoration of the resting potential of a neurone after the action potential and hyperpolarisation have respectively occurred. I wonder: which type of ion, Na+ or K+, is it that moves against its electrochemical gradient during the restoration of the resting potential of a neurone if the work of the sodium-potassium pump does indeed involve secondary active transport that by definition does indeed involve one type of the 2 ions moving along its electrochemical gradient and one type moving against it? I also therefore wonder which of the 2 types of ion moves along its electrochemical gradient? If it is, for example, the K+ ions that move against their electrochemical gradient, am I to then understand that during hyperpolarisation there are still more K+ ions inside the axon then outside even though the inside of the axon is very negative. If, for example, it is on the other hand the Na+ ions that move against their electrochemical gradient, am I then to understand that there are more Na+ ions outside the axon then inside even after the great influx of Na+ ions during the transmission of an action potential? Thank you very much - your help is greatly appreciated.
Re: Why is the work of the sodium-potassium pump secondary active transport?
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