We began our visit to the physical structure of the brain with neurons – the most commonly known brain cells – and we finish with glia cells.
Glia (which means “glue”) cells provide support to the brain. They outnumber neurons by about ten to one (I’ve also seen that described as 50 to 1!), and with all their numbers they might also be contributing to thought, though this has yet to be confirmed. Since there are some one hundred billion neurons, just try to imagine how many glia cells there are!
These good old glias are like a child’s devoted nanny. They take care of the neurons from the very beginning as the baby is forming in the womb. They feed the neurons and help the neurons traverse the brain. Turns out that the more any set of neurons is used by the brain, the more glia cells those neurons need. Happily, the glia cells can reproduce so we never run out of them.
Another task for the glias is to produce myelin, which is the substance that coats the axons of neurons. More myelin equals faster communication lines between neurons, kind of like a snowboard that goes faster and smoother with wax on it.
Glia cells (also spelled Glial) do not have axons. You can see a picture of a glia cell at the Brain Explorer site.
It is now clear that glial cells do far more than just support and nourish neurons. For example, not only do astrocytes regulate synaptic transmission, but they also synthesize neurotransmitters and signal to neurons.
It is now clear that glial cells are far more than just support cells. For example, we now know that oligodendrocytes can communicate with neurons,
and that astrocytes regulate synaptic transmission. AStrocyte dysfunction has also been implicated in a number of neurodegenerative diseases.
“These good old glias are like a child’s devoted nanny.”
The other analogy I have heard is that glial cells are like the sober friends of drunk, stumbling neurons, carting them home after an extensive night of firing action potentials, running low on transmitters, and throwing up ions until their electric potential is completely imbalanced.