Fundamentals Of Neuroscience
Article 3: Ion Channels
The neuron, like any other cell, has a plasma membrane. This membrane exists to separate the internal environment of the cell from the outside world.
Within these membranes, there are special elements called ion channels and pumps.
These ion channels and pumps allow the exchange of ions from the cell and extracellular space and vice versa.
That brings us to this diagram above, which is a more complex version of the diagram we saw in Article #2.
While there is a ton of information to be discussed about ion channels alone, here we will pay special attention to the Na+/K+ ATPase pump.
This pump uses ATP, the fundamental energy unit of our body, to produce an uneven distribution of Sodium(Na+) and Potassium(K+) across the plasma membrane.
Leak channels are special ion channels that are always open. They allow the free flow of ions down their concentration gradients.
By using the concentration gradient produced by the Na+/K+ ATPase pump, the leak channels allow the production of a voltage difference between the external and internal environments of the neuron.
This voltage is known as the membrane potential, and it is typically between -65mV and -70mV.
This now prepares us to discuss the topic of the next article, action potentials.
A fundamental principle in this series will be the following:
“The change in membrane potential is neural signaling.”
Indeed, we will see that the all-important action potential arises from the neuron’s ability to allow rapid influxes and effluxes of ions.
