(Click to enlarge)
Encyclopedia Britannica |
Channels, Channels, Channels!
There are 9 different kinds of gates/channels/ pumps in neurons. I will group them here by their function which can help you remember them.
So, just to be clear this is how I categorized the channels by what they do.
Maintain membrane potential:
Na+ diffusion channel (Sodium leak channel)
K+ diffusion channel (Potassium leak channel)
Sodium-potassium pump
Involved in action potentials:
Voltage-gated sodium channels (allow sodium to rush in, resulting in depolarization)
Voltage-gated potassium channels (allow potassium to rush out, resulting in repolarization)
Voltage-gated calcium channels (are triggered at the end of the axon, and trigger release of neurotransmitters)
Involved in post-synaptic reception:
Chemically-gated Na+/K+ channel (Ligand-gated sodium-potassium channel)
Chemically-gated K+ channel (Ligand-gated potassium channel)
Chemically-gated Cl- channel (Ligand-gated chloride channel)
Here is a diagram I made, grouping the channels by function (each function has the same shape).
Notice that the 3 responsible for membrane potential (triangles) are all over the whole cell membrane. The 3 responsible for action potentials (stars) are only on the axon (from axon hillock to axon terminal) because that is where the action potentials happen. The 3 responsible for post-synaptic reception are the circles and are on the cell body. I put them only on the post-synaptic neuron for simplicity. But obviously the cell body of the pre-synaptic neuron would also have them.
The influx of Calcium triggers the neurotransmitters to exocytose and that is the end of the message for the pre-synaptic neuron.
Example of chemically-gated channels with Chloride channel being activated (notice the red triangles represent neurotransmitter and they do not enter the cell) |
Source |
Click here to learn about action potential |
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