This lesson explores two major parts of the nervous system. You'll learn what the nervous system is and what types of problems can affect each system.
As humans, we love to file and categorize things into neat piles to access and understand information better. You do this on your computer with file folders, your local library does this with books, and our tax codes are categorized into all sorts of numbers. Of course, in the case of the latter, it's convoluted to the point of wanting to pull your hair out.
But in this lesson, I won't be like the IRS in that regard. Instead, I'll classify neurological disorders for you into two simple categories.
Central Nervous System Disorders
The first category involves central nervous system disorders. The central nervous system (CNS) is the part of the nervous system that includes the brain and spinal cord. The nervous system is the part of the body that transmits electrochemical signals to stop or start processes within our body.
The brain is like a smartphone. It has all the chips and parts that think and send out commands. The spinal cord is more like the USB cord you hook up to the smartphone. It helps to relay commands from the brain into this cord and out into other areas we'll discuss in the next section.
Anyways, when any part within the spinal cord or brain gets sick, this is classified as a central nervous system disorder. Let's take a little peek at some of these conditions.
Sometimes, like a virus on a computer, an infectious problem causes the inflammation of the brain or meninges. The meninges is the tough outer layer that surrounds and protects the brain and spinal cord. It's like the cover you use for your smartphone. So, when either the brain or the meninges are inflamed, we term this encephalitis and meningitis, respectively.
Other times, a disorder in the CNS is caused by an interruption of the power supply to it, kind of like when the battery in a phone dies. Once the battery is dead, the phone dies. It works the same way in the body. Except in the CNS, the power supply is cut off when the blood flow is interrupted to it, by something like a blood clot, as in the case of a stroke.
But the power supply doesn't have to be interrupted for your phone to go out of sync. I know you've had cases where it seems like there were random glitches that popped things up on your phone that were not supposed to be there. This is usually because of a malfunctioning code after an update. Within our body, our genome - or DNA - is our code, and it can also malfunction and cause things to pop up that weren't really meant to be there. This may result in tumors or brain cancer. And brain cancer is another problem that can affect our CNS. Examples of brain tumors and cancer include meningiomas, oligodendrogliomas, and astrocytomas.
The fact that these glitches occurred may have caused you to hit or throw your phone, further damaging it. Our own body can also attack itself. We term this autoimmune disease. One very famous disease that includes an autoimmune component that destroys the central nervous system is called multiple sclerosis. Trauma, of course, doesn't have to come from within. You can also hit your head in an accident, and this may result in internal bleeding.
But hitting your head or phone is kind of an obvious thing. I think you'll agree with me that sometimes things within the structure of the phone, like the wiring and chips, sometimes just degenerate as a result of many problems over time or sometimes without a very well-known cause, leading to the malfunction of the phone. In the same spirit, neurodegenerative disorders are unfortunately not uncommon; they sometimes have many causes and other times no definable cause at all. Examples of neurodegenerative disorders include Alzheimer's, ALS, Parkinson's, and Huntington's disease.
Peripheral Nervous System Disorders
In contrast to the CNS, our body has something known as the peripheral nervous system (PNS). The PNS is the part of the nervous system outside of the brain and spinal cord. Meaning, it's the nerves running through your hands, feet, to your skin, mouth, organs, and so forth. If it's not in the spinal column or your skull, then for all practical purposes, it's part of the peripheral nervous system. In terms of function, the peripheral nervous system receives signals from, or sends signals to, the central nervous system.
So, the nerves that activate your muscles to move receive cues from the CNS. But the receptors in your mouth that give you the sensation of really spicy food send signals to the CNS.
To me, the peripheral nervous system is like the stuff you hook up that phone's USB cord to, like a sound system in your car. By doing so, the CNS can send signals to the sound system, part of our peripheral nervous system, and tell it to play a certain sound. In the real world, it would be like the brain telling your mouth, tongue, and vocal cords to produce a sound.
Like our CNS, the peripheral nervous system can also be affected by many problems.
If a nerve is compressed, it may not be able to send or receive signals very well. One very famous such disorder of nerve compression in the PNS is carpal tunnel syndrome. This odd signaling causes pain and weakness in the affected hand.
In other instances, the PNS is actually affected by a disease process that initially has nothing to do with the peripheral nerves. Diabetic neuropathy occurs because a condition called diabetes mellitus, something that causes elevated blood sugar, by extension injures blood vessels supplying these peripheral nerves, resulting in their dysfunction. This causes shooting pain in some places (and numbness in others), urinary problems, and much more.
And just like our CNS can be damaged by a traumatic injury, so too can the peripheral nervous system. Brachial plexus injuries may occur in cases of shoulder trauma and might result in improper muscle control of the affected hand or even paralysis. A plexus, by the way, refers to a network of nerves that intersect with one another. It's like a crossroads of sorts between the information highways that carry electrical signals throughout your body. So, if you took the wires in whatever you attached your phone to and pulled them apart or damaged them, then the peripheral device you hooked up will no longer work very well.
But our peripheral nervous system isn't much different from the central nervous system, as it can be affected by every major category we went over in the CNS section. Tumors and autoimmune disease (sometimes resulting from infectious causes, as in the case of Guillain-Barre Syndrome) can be very devastating upon the body and both parts of the nervous system.
The nervous system is the part of the body that transmits electrochemical signals to stop or start processes within our body. It is divided into two main categories.
The first category involves the central nervous system (CNS) disorders. The central nervous system is the part of the nervous system that includes the brain and spinal cord.
The other part of the nervous system is the peripheral nervous system (PNS). The PNS is the part of the nervous system outside of the brain and spinal cord.
This lesson should have taught you that a multitude of things can affect either one, including trauma, autoimmune disease, cancer, bad genes, degenerative disorders, and much more.
Following this lesson, you should be able to:
- Identify the purpose of the nervous system
- Describe the central and peripheral nervous systems
- Explain the causes of central and peripheral nervous system disorders