The Systems of the Body
The Central Nervous System
Back to the Basics - Our Body
by William Ferrell, MD, Raleigh Neurology Associates
April 2010
OverviewWhen it comes to the central nervous system (CNS), the name says it all. This system is central to everything you think or do. Whether it’s telling your hand to grasp a coffee cup, taking in visual and auditory information during a movie, or regulating your balance as you walk, your CNS is always at work.
For this reason the CNS, which is composed of the brain and spinal cord, is often described as the main "processing center" for the entire nervous system.
- The brain is divided into several different parts, each controlling specific actions and thought processes. Four main lobes represent this division of activity — the frontal, the parietal, the occipital, and the temporal. The frontal lobe is primarily responsible for conscious thought. The parietal lobe specializes in integrating sensory information. The occipital lobe deals with sight. And the temporal lobe handles smell and sound.
- The spinal cord, commonly known as the backbone, is the "information highway" of the body. Attached to the brain at the brain stem, it serves as a pathway to the brain for sensory information and as a conduit for information from the brain to the muscles and other organs. The spinal cord is made up of bones called vertebrae and is around 18 inches long in men and 17 inches long in women.
How It WorksThe CNS functions by relaying messages back and forth from the brain to different parts of the body. It does this via the billions of neurons that travel along the spinal cord. Attached to the spinal cord are threadlike nerves that extend out to each body part and organ. These nerves make up the peripheral nervous system. Chemicals travel from neuron to neuron, moving a nerve impulse forward until the message reaches its final destination.
A simple example of this is your reaction when you touch something very hot. The nerves in your skin send a message up your spinal cord to your brain, which then replies by telling your muscles to move your hand.
Central Nervous System ProblemsBecause the CNS is responsible for so many functions within the body, there are also many disorders that can occur from abnormalities within this system.
Seizures — A seizure occurs when there is abnormal electrical activity in the brain. This can be caused by many factors, including medical problems (such as low blood sugar or sodium levels), tumors, infection, head injury, and illegal drug usage.
Depending on the part of the brain affected, seizures may result in a variety of symptoms, such as muscle twitching, convulsions, unusual sensations, and loss of consciousness.
If a person experiences recurring seizures, physicians may prescribe medication based on the type of seizure, the person’s age, and any other medical conditions the patient may have. These drugs are used to prevent the symptoms, such as convulsions, associated with seizures but usually do not target the underlying cause.
Parkinson’s Disease — Parkinson’s disease is caused by an impairment or deterioration of neurons in the part of the brain known as the substantia nigra. This degeneration results in a lack of the neurotransmitter dopamine, leading to impairment of motor skills, speech, and other body movements.
There are several medicines that can ease the symptoms of Parkinson’s disease. Most work by replacing or mimicking dopamine, which improves the tremor, imbalance, rigidity and slowness associated with the disease.
The progression of the disease differs from person to person. But with the appropriate treatment, most people with Parkinson’s disease can lead productive lives for many years after their diagnosis.
Dementia — Though there are several different diseases associated with dementia (such as Alzheimer’s disease and Huntington’s disease), all involve a loss of brain function. This deterioration can affect memory, thinking, language, judgment and behavior.
Some treatments may help slow or minimize the development of dementia symptoms. Several medications attempt to boost or regulate chemical messengers in the brain that are associated with memory, judgment, or learning. While none of the currently available medications stop or reverse the progression of dementia, various ongoing drug trials may offer ways to halt degenerative changes in the brain.
Dr. William Ferrell has practiced with Raleigh Neurology Associates since 1991. He frequently treats patients at WakeMed. Home to the only nationally certified Primary Stroke Center in Wake County, WakeMed partners with board-certified neurosurgeons, orthopaedic surgeons, neurologists, critical care intensivists, neuroradiologists and rehabilitation experts to create a coordinated multidisciplinary team