So now let's talk a little bit about what happens when we damage nervous tissue and if and how it can be repaired.
Although the nervous system is able to exhibit plasticity
which involves the ability to change based on experience such as learning things over time,
neurons also have a limited ability to regenerate themselves which involves replicating or repairing.
In the central nervous system which is the brain and the spinal chord, there is very little to no repair.
This is due to several different factors. First, their inhibitory influences from the neuroglial cells
such as the oligodendrocytes found wrapped around these neurons.
Secondly, after fetal development, there's an absence of the growth-stimulating cues that we find during development.
Lastly, there's a rapid formation of scar tissue in the central nervous system
that leaves little room for repair to take place.
This is different in the peripheral nervous system.
In the peripheral nervous system, repair is possible as long as the cell body is intact,
the Schwann cells are still functional, and scar tissue has not formed too quickly.
The steps that are involved in the repair process of the peripheral nervous system include chromatolysis.
In this step, the Nissl bodies which are found inside of the cell body of the neuron
are going to start to degenerate and migrate away from the cell body.
It's called chromatolysis because the Nissl bodies have a very distinct color to them.
In the second step of the repair process in the peripheral nervous system, we have Wallerian degeneration.
During this step, the part of the neuron that is distal to the injury begins to degenerate.
Finally, we have the formation of the regeneration tube.
This begins the repair process of the part of the neuron that is distal to the neuron injury.
We will conclude this lecture by talking about the different types of disorders that affect the nervous system.
The first of those disorder that we will discuss is multiple sclerosis.
Multiple sclerosis affects the myelin sheath of the peripheral nerves.
This then slows down the speed of conduction to the skeletal muscles.
A second disorder in the nervous system is epilepsy which usually leads to epileptic seizures.
In this, the motor and sensory neurons are attacked as well as psychological function being attacked.
Interestingly about epilepsy is it usually does not hurt or bother intelligence.
A third type of disorder found in the nervous system is excitotoxicity.
In this, you have a high level of glutamate that's found in the interstitial fluid
which leads to a prolonged activation of the neuron.
In this case, the neuron is never getting any rest and is pretty much activated to death.
This usually happens in situations where you have oxygen deprivation such as during a stroke.
And then finally, we have depression in which there are many different types.
Unlike many of these other nervous system disorders have
or the exact cause of depression is not yet known and is still being studied.