Graduate Psychology

Central Nervous System

from Gale Encyclopedia of Nursing and Allied Health

View article on Credo

Def init ion

The central nervous system (CNS) consists of the brain and spinal cord.

Descript ion

Comprised of the brain and spinal cord, the CNS is central to the body as opposed to the peripheral nervous system. It is responsible

for unconscious and conscious body functions as well as intellectual functions that allow humans to think. The neuron is the basic

nerve cell of the nervous system, however, the nervous system contains many types of cells other than nerve cells. The nerve cell

consists of a nucleus in

a cell body, dendrites, and axons. The CNS is heavily guarded with protective features, however, this does not make it immune to

disease and disorder. The CNS is cushioned with cerebrospinal fluid (CFS), protected by three layers of meninges, and protected from

the body by the blood-brain barrier. The blood-brain barrier prevents harmful substances and disease-causing organisms from

contaminating the bloodstream entering the CNS.

The skull (cranium) encloses the brain. Three main areas of the brain, the cerebrum, cerebellum, and brainstem, contain myelinated

nerve fibers and white matter, in contrast to the cortex of the brain, the layer of gray matter. The cerebrum, the largest part of the

brain containing the left and right hemispheres, controls conscious activities like motor functions. The cerebellum, located above the

brainstem, communicates with other regions of the brain and spinal cord to control balance and coordination. The brainstem, the

lowest part of the brain extending to the spinal cord, controls unconscious activities necessary for survival, such as breathing and

blood pressure . The spinal cord is protected by the vertebral column from the cervical area to the sacrum. The spinal cord nerves

relay sensory information to the brain and motor information to the body.

Funct ion

The central nervous system (CNS) is a processing center that integrates sensory and motor activities via the brain and spinal cord.

Nerves are like an electrical wire with an insulating sheath, called myelin, that facilitates the smooth, high-speed transmission of

messages. Information in the nervous system is carried by brief electrical impulses that are conducted away from the body of the

nerve cell along the axons. When impulses reach the tips of axons, information is transmitted to the next nerve cell in line, or to a

muscle or organ. At the point of contact, or synapse, the information is carried across the gap between cells by neurotransmitters. The

CNS has two-way communication. Nerve fibers either relay messages to the brain to communicate sensory stimuli, or they relay

messages away from the brain to the

https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

body's tissues and organs. It is through the spinal cord that messages are sent back and forth to the brain. Spinal nerves in the spinal

cord connect the message relay system to rest of the body

Role in human health

Many health care providers, neurologists, neurosurgeons, physiatrists, neuropsychologists, nurses, occupational therapists, speech

language pathologists, physical therapists, and vocational rehabilitation counselors, play a role on the health care team and share in

the responsibility of the neurologic patient. A combination of methods for assessing patients with neurologic diseases and disorders

enables health care professionals to make informed treatment recommendations. These include neurologic and physical

examination, laboratory tests such as lumbar puncture , brain-imaging scans such as MRI, neuropsychological testing, and nuclear

medicine tests. Treating neurologic diseases and disorders requires active patient participation along with education and support from

health care professionals. While patient education may be time-consuming, it is extremely important to the process of maintaining

health and preventing disease.

Common diseases and disorders

There are hundreds of disabling neurological diseases and disorders that affect every age, race, and ethnicity. A few examples

include developmental disorders (cerebral palsy), degenerative diseases (Par-kinson's and Alzheimer's disease), metabolic

diseases (Tay-Sachs disease), cerebrovascular diseases (stroke), autoimmune diseases (multiple sclerosis), and tumors

(glioblastoma).

Alzheimer 's diseaseAlzheimer 's disease

Alzheimer's disease (AD), a progressive, neurodegenerative disease, is the most common cause of dementia in later life. The course

of the disease varies from person to person. Although the cause of AD is not yet known, researchers have found a familial tendency

for AD. They have also implicated several possibilities including genetics, environmental factors, and biochemical changes in the brain

caused by low levels of certain neurotransmitters. AD usually begins after age 65, however, it may have an early onset as early as age

40.

SYMPTOMS.

The severity and progression of symptoms vary from person to person. Some of the early symptoms of AD, such as forgetfulness or

loss of concentration, can easily be overlooked because they resemble signs of aging or could result from fatigue, depression, or the

use of certain medications. Symptoms of AD include:

memory loss, confusion, loss of concentration

difficulty recognizing family and friends

poor judgment, indifference

changes in behavior and personality

disorientation, wandering, sleep disturbance

https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

agitation, anxiety, depression

There is no specific test to confirm a diagnosis of AD. A combination of tools including brain imaging technologies, patient and family

history, physical and neurological examination, and neuropsychological testing are utilized to definitively diagnose AD. There is no

cure for AD and no clinically proven way to slow the progression of the disease. For some patients, medication may alleviate some of

the symptoms. Treatments are intended to make the patient more comfortable.

StrokeStroke

Stroke, also called cerebral vascular accident (CVA), occurs when the blood flow to part of the brain is disrupted. There are primarily

two categories of stroke, ischemic and hemorrhagic. The most frequent cause of stroke is a blockage (ischemic) of a blood vessel in

the brain. The blockage can have several causes but all with the same result, brain cell damage or death. Brain cells cannot survive

without a blood supply of oxygen and nutrients. Blockage of blood flow in the brain can be caused by a clot in a blood vessel

(thrombosis) of the brain, the movement of a clot from another part of the body (embolism) to the brain, or a severe narrowing of an

artery in the brain (stenosis). In a hemorrhagic stroke, a blood vessel in the brain bursts, bleeding into the brain (intracerebral

hemorrhage) or into the spaces surrounding the brain.

SYMPTOMS.

The signs and symptoms of stroke depend on the areas of the brain affected and the functions they control. The right cerebral

hemisphere controls the left side of the body and the left cerebral hemisphere controls the right side of the body. The symptoms of

stroke may be:

sudden numbness or weakness, especially on one side of the body

sudden confusion, difficulty speaking, or understanding speech

sudden difficulty seeing in one or both eyes

sudden trouble walking

sudden dizziness, loss of balance or coordination

sudden severe headache

paralysis, pain

Risk factors for stroke are either changeable or not. For example, a person cannot change her or his age or family history, but can

change behaviors, such as smoking, that put a person at risk for a stroke. Risk factors for stroke include:

high blood pressure

heart disease

diabetes

smoking

heavy alcohol consumption

drug abuse

high blood cholesterol levels

family history of stroke or transient ischemic attack (TIA)

age over 55

According to the National Center for Health Statistics, stroke is the fourth leading cause of death in the United States. In order to

improve this statistic, patients need prompt interventions. The public education campaign, “Know Stroke: Know the Signs. Act in Time,”

promoted by the National Institute of Neurological Disorders and Stroke (NINDS) teaches people how to recognize the signs and

symptoms of stroke and the importance of prompt medical treatment to improve recovery. Tissue plasminogen activator (t-PA), the first

Food and Drug Administration (FDA) approved acute ischemic stroke treatment, needs to be given within a three-hour window of the

onset of symptoms to dissolve the clot. Stroke is diagnosed by a neurological examination, blood tests, brain imaging scans, Doppler

ultrasound, or arteriography.

Multiple scleros isMultiple scleros is

Multiple sclerosis (MS) is a common neurological disease that occurs mainly in young adults. The course of the disease varies from

https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

person to person and is categorized by type. Relapsing-remitting MS (RRMS) has a course of acute attacks with full or partial recovery

during remissions. Secondary progressive MS (SPMS) is initially relapsing-remitting and then becomes progressive. Primary

progressive MS (PPMS) has a progressive course from the beginning of the disease with no remissions. Progressive-relapsing MS

(PRMS) has a progressive course from the beginning with acute relapses, with or without full recovery.

MS is believed to be an autoimmune disease, where the immune system targets the myelin in the central nervous system. MS is the

most common demyelinating disease. During an attack (exacerbation), inflammation occurs in the white matter of the central nervous

system. This process is followed by destruction of myelin causing areas called plaques. Not only is the myelin damaged, but the attack

may also damage or sever the nerve fibers underneath the myelin. The nerve cannot conduct or send a signal properly without the

myelin sheath.

MS can be difficult to diagnose because there are other diseases with similar symptoms, and there is no specific test to confirm the

diagnosis. A process of elimination may be done along with a combination of imaging technologies such as MRI, CSF analysis , evoked

potentials (EVP), medical history, and clinical examination.

SYMPTOMS.

The symptoms of MS are unpredictable, can vary greatly from person to person, and can be intermittent. The neurological symptoms

of MS are the result of demyelination. Symptoms include:

blurred, double vision, and blind spots

numbness, tingling, and paresthesias (pins and needles)

fatigue, dizziness, and vertigo

difficulties with memory loss, concentration, and attention

difficulty with coordination, balance, and gait

muscle and nerve pain, muscle weakness, and tremors

bladder and bowel problems

KEY TERMS

Autoimmune—

The immune system sees itself as a foreign antigen and attacks a part of the body.

Cerebrospinal f luid—

Fluid surrounding and cushioning the brain and spinal cord.

Exacerbation—

The appearance of new symptoms or the aggravation of old symptoms.

Gene—

Basic units of heredity in every cell that tell the cell how to put together different proteins.

Meninges—

Three layers of protective connective tissue covering the brain and spine consisting of the pia mater, arachnoid, and dura mater.

Myelin—

A protective coating made of fat and protein that insulates the nerve and enhances efficient nerve fiber conduction.

Neurotransmitter—

A chemical that transmits a nerve impulse at the synapse.

There are many conventional and alternative treatment therapies to alleviate the symptoms of MS, but there is no cure. However, four

medications have been shown to slow down disease progression. The FDA approved Interferon beta 1b (Betaseron) in 1993,

Interferon beta 1a (Avonex) in 1996, and glatiramer acetate (Copaxone) in 1996 for the treatment of RRMS. They were clinically shown

to decrease the frequency and severity or attacks by approximately 30%. Mitoxantrone (Novantrone), a chemotherapy agent that

suppresses immune function, was FDA approved in 2000 for the treatment of worsening RRMS and SPMS.

ResearchResearch

Research in neuroscience and the development of new research techniques and technologies offer hope to the millions of patients

https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

and families affected by neurological diseases and disorders. Research into new treatments does not solve the problem, therefore,

scientists are researching areas such as neurogenetics to discover how to prevent certain disorders. New treatment options and the

possibility of cures can bring a sense of optimism to patients. However, the research process takes years before a treatment is

available to the public. Only controlled clinical trials with human participants can determine if a treatment is safe and effective for

patients.

QUESTIONS TO ASK YOUR DOCTOR

How can you determine if a person's symptoms are the result of Alzheimer's disease versus aging?

What types of treatment are available for a person with early Alzheimer's disease?

Since stroke is common in our family, what lifestyle changes do you recommend for reducing my risk of the disease?

What tests will you perform to confirm a diagnosis of multiple sclerosis in my husband?

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision: DSM-IV-TR.

American Psychiatric Association Washington, DC, 2000.

Spence, David; Henry J. M. Barnett. Stroke Prevention, Treatment, and Rehabilitation. McGraw-Hill Professional New York, 2012.

Weiner, Howard L.; James M. Stankiewicz. Multiple Sclerosis: Diagnosis and Therapy. Wiley-Blackwell Chichester, West Sussex;

Hoboken NJ, 2012.

OTHER

CNS Degenerative Diseases. http://library.med.utah.edu/Web-Path/TUTORIAL/CNS/CNSDG.html (accessed May 6, 2012).

Stroke. MedicineNet.com. http://www.medicinenet.com/stroke/article.htm (accessed May 6, 2012).

What Is Alzheimer's?http://www.alz.org/alzheimers_disease_what_is_alzheimers.asp (accessed May 6, 2012).

ORGANIZATIONS

Alzheimer's Association. 225 N. Michigan Ave., 17th floor, Chicago, IL 60601-7633. (312) 335-8700. http://www.alz.org/. [email protected].

American Academy of Neurology. 1080 Montreal Ave., St. Paul, MN 55116. (651) 695-1940. http://www.aan.com/.

http://www.aan.com/contact/.

American Stroke Association. 7272 Greenville Ave., Dallas, TX 75231. (888) 478-7653.

http://www.strokeassociation.org/STROKEORG/.

Multiple Sclerosis Association of America. 706 Haddonfield Rd. Cherry Hill, NJ 08002. (800) 532-7667. http://www.msassociation.org/.

[email protected].

National Institute of Neurological Disorders and Stroke. National Institutes of Health. Bethesda, MD 20892. (800) 352-9424.

http://www.ninds.nih.gov/. http://www.ninds.nih.gov/contact_us.htm.

National Multiple Sclerosis Society. 733 Third Ave., 3rd floor, New York, NY 10017. (800) 344-4867.

http://www.nationalmssociety.org/index.aspx. http://www.nationalms-society.org/ContactUs.aspx.

Deborah Eileen Parker, R.N.

© 2013 Gale, Cengage Learning

https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

APA Parker, D. E. (2013). Central nervous system. In Gale (Ed.), The Gale encyclopedia of nursing and allied health (3rd ed.). Farmington, MI:

Gale. Retrieved from https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

Chicago Parker, Deborah Eileen. "Central Nervous System." In Gale Encyclopedia of Nursing and Allied Health, edited by Gale. 3rd ed. Gale,

2013. https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0

Harvard Parker, D.E. (2013). Central nervous system. In Gale (Ed.), The Gale encyclopedia of nursing and allied health. (3rd ed.). [Online].

Farmington: Gale. Available from: https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0 [Accessed 11

January 2019].

MLA Parker, Deborah Eileen. "Central Nervous System." Gale Encyclopedia of Nursing and Allied Health, edited by Gale, 3rd edition, 2013.

Credo Reference, https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0. Accessed 11 Jan. 2019.

https://search.credoreference.com/content/entry/galegnaah/central_nervous_system/0