Central and Peripheral Nervous Systems, Research Paper Example

Both the central and peripheral systems send and receive electrical signals to and from the brain to the muscles and nerves. So those signals are the mode of communication between the brain and the body. When they are stopped or interrupted, the body has no information or false information to act on. So it either cannot move at all or it moves in accordance to signals sent in error due to injury, illness, intoxication, or reflexes based on misperceptions. So we can see that the most basic similarity is electrical (Encyclopedia Britannica n.d.).

The two systems are fundamentally different in how they provide mobility, but they work together seamlessly. The central system is encased in bone, namely the skull and the spine. The brain processes and coordinates all the signals it is constantly getting from the limbs, organs, and nerves spread throughout the body. Except for the retina, which is considered part of the central system, the peripheral system is responsible for sending those signals. In other words, it is the central systems that thinks. The peripheral system isn’t as protected, and it doesn’t think in the sense that the brain does. It receives stimulation and information from both inside and outside the body and passes it to the brain, which then tells the receiver (a finger, the eyes, a patch of skin) that something feels good, is hot, sharp, painful, etc. But of course the spine doesn’t think either, and in this sense might be informally thought of as the key component of the peripheral system, even as it is formally defined as being in the central system. The key concept here is central. All nerve signals eventually pass through the spine to the brain, making it like a telephone or railroad trunk line, in which the various branches of a network share the same lines. So the spine is seen as an extension of the brain, rather than the peripheral system.

The peripheral system is itself divided into two parts, the autonomic and the somatic. Think of the autonomic system as automatic. It controls things we can’t control consciously at all or only to a limited extent. Examples are pulse, breathing, and digestion. The somatic system controls voluntary use of the muscle contraction via the skeleton, as well as reflexes, which require simultaneous signals to the brain and spine.

Anyone who thinks about it at all will at first think that the central nervous system is the most important, because you couldn’t really be considered a full human being without a brain. But the peripheral system makes us fully effective human beings, as it enables us to walk, talk, eat, drink, have sex —to use our bodies to their fullest physical extent. That includes regulating breathing, which keeps our brain supplied with oxygen without our having to think about it, as when we are asleep. So it’s not really meaningful to speak even of the central nervous system as the most important, except in the real-world exceptions of polio- and accident victims kept alive by iron lungs and other clinical life-support systems until (if ever) the patient can recover. Although it’s true that no one would ever claim that the peripheral system is more important than the central system, it surely is most important when it comes to the quality of normal, day-to-day life. From this perspective, both systems should be views as a holistic entity, one system.

Neurological disorders definitely affect both the central and peripheral systems, but not “usually” in the sense of other diseases, like the common cold, the flu, and the whole range of conventional diseases that affect the body itself. Neurological diseases are relatively rare, but do become more common as we get older and begin to wear out, and so become more susceptible to injury, infection, and general genetic breakdown. It’s clear that the spine is susceptible to disease of the bone, and to injury, as is the skull. But in general the peripheral systems is more prone to disorders because it is spread throughout the body and in a way has more physical work to do than the central system, which basically receives, reacts in the brain, and then sends. It has no spine, nor a blood-brain barrier, to keep it relatively protected from injury and infection. We can say that whatever illnesses and injuries the body itself is prone to are the illness and injuries the peripheral system can be affect by. And whether central or peripheral, both being composed of living tissue, both are susceptible to all the things that can go wrong with living tissue, starting with the DNA molecule. In the presence of radiation, the damage starts at the electron level.

A classic disease of the peripheral system is leprosy, also known as Hansen’s Disease (PubMed Health 2011). It has a specific infectious cause, the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. The bacteria seek the limbs, nose, ears, and penis because they are heat sensitive, and gradually reduce sensation in the areas they infect. It is treatable now with antibiotics, and those under treatment quickly lose their infectiousness, and the bacterium was never overly infectious anyway, as most people are naturally immune. There is now also a vaccine available. Consequently the rate of new infections in the U.S. is very low.

Diseases of the central nervous system are broken down into spinal cord (myelopathy) or brain (encephalopathy). Encephalitis is a catch-all term denoting inflammation of the brain. It has many specific causes, from infectious viral and bacterial sources, or from non-infectious causes, such as head trauma, poisoning, and autoimmune disorders (The Lance 2010). Treatment will of course depend on which kind of encephalitis is present, so the correct diagnosis of the classic symptoms of head ache, fever, sore neck, memory loss, etc., is critical, as (to cite one very basic example) a viral infection would not be treatable with antibiotics. Treatments will include both fighting the infection itself as well as the resultant inflammation (NINDS 2011).

Multiple sclerosis affects both the brain and the spinal cord, gradually depriving the nerves of their protective covering, called myelin. It is another autoimmune disease, but the cause of the disorder and the degree of its infectiousness remains unknown, and there is no cure. Treatments programs focus on slowing the progress of the disease, rather than curing the disease itself. Numerous drug regimens also address secondary complication like fatigue and depression.

References

Encyclopedia Britannica. (n.d.) Transmission of information in the nervous system. Retrieved from http://www.britannica.com/EBchecked/topic/409665/nervous-system/75829/The-ionic-basis-of-electrical-signals

NINDS. (2011.) National Institute of Neurological Disorders and Strokes. Peripheral Neuropathy Fact Sheet. http://www.ninds.nih.gov/ disorders/ peripheralneuropathy/ detail_peripheralneuropathy.htm

PubMed Health. (2011.) Leprosy. Retrieved from http://www.ncbi.nlm.nih.gov/ pubmedhealth/PMH0002323/

The Lancet. (2010.) Infectious Diseases. Retrieved from http://www.thelancet.com/ journals/laninf/article/PIIS1473-3099(10)70222-X/abstract