The Nervous System

The nervous system is a network of specialized cells that communicate information about an animal's surroundings and itself. It processes this information and causes reactions in other parts of the body. It is composed of neutrons and other specialized cells called glia, that aid in the function of the neurons. The nervous system is divided broadly into two categories; the peripheral nervous system and the central nervous system. Neurons generate and conduct impulses between and within the two systems. The peripheral nervous system is composed of sensory neurons and the neurons that connect them to the nerve cord, spinal cord and brain, which make up the central nervous system. In response to stimuli, sensory neurons generate and propagate signals to the central nervous system which then processes and conducts signals back to the muscles and glands. The neurons of the nervous systems of animals are interconnected in complex arrangements and use electrochemical signals and neurotransmitters to transmit impulses from one neuron to the next. The interaction of the different neurons form neural circuits that regulate an organism's perception of the world and what is going on with its body, thus regulating its behavior. Nervous systems are found in many multicellular animals but differ greatly in complexity between species.^[1]

The... Spinal Cord!

Your spinal cord is connected to the brain and is about as thick as your finger. From the brain, your spinal cord goes down the middle of the back and is covered and protected by the vertebrae. The spinal cord is surrounded by a clear liquid called cerebral spinal fluid that acts as a cushion.

Receptors in the skin send information to the spinal cord through the spinal nerves. The cells for these nerves are located in something called the dorsal root ganglion. The nerve fibers enter the spinal cord through a dorsal root. Many cells in the nerve of the spinal cord send fibers through the nerve to muscles to control movement.

The nerves inside the spinal cord are grouped together in different bundles called ascending and descending tracts. Ascending tracts in the spinal cord carry information from the body, upwards to the brain, like touch and pain. Descending tracts in the spinal cord carry information from the brain down to control body functions.

What do You do Without Nerves?

Did you know that some people don't have nerves? Probably not, because only 35 Americans can't feel pain. Congenital insensitivity is caused when your nerves do not connect to the part of the brain that can feel pain. Sounds good right? Wrong! It is extremley dangerous to not have nerves, especially for children because they have to be watched very closely and have to carry around a device that can tell them the temperatures of things. According to pravda.com, a three year old girl was touching a hot oven but couldn't feel the tempereture, and her parents later found her smiling with blood all over the kitchen. Another thing that can happen with CIPA (congenital insensitivity to pain) is Anhidrosis, which is the inability to control your body's temperature. When this happens, you are unable to sweat which can cause you to overheat, or underheat. One boy in China's body temperature is 43 degrees F. This disease is very tragic and most people that have it don't live past 25 because they catch simple illnesses but they can not detect it. Scientists still can't think of a cause for it, and it is the rarest disease in the entire world.
By, Andy

Here are parts of the nervous system.

Parts of The Nervous system

The nervous system is one of the most important parts of the human body. In fact, without it, you wouldn't be able to be reading this right now! The nervous system has 3 parts to it, the spinal cord (that's what is holding you up right now), the brain (the big cheese and or head honcho of the body), and millions of tiny nerves that develop your sense of touch. Even though the nervous system is very strong, there are many diseases that can affect the nervous system including: brain tumors , bipolar disorder, Alzheimer's disease , Parkinson's disease , Huntington's disease, fragile X syndrome and spinocerebellar atrophy. The brain and nervous system form an intricate network of electrical signals that are responsible for coordinating muscles, the senses, speech, memories, thought and emotion. The brain sends messages to your nerves telling them to move your arm up, or stomp your foot. Your nerves are very thin, the longest ones stretch up to three feet long! Want to know what all the parts of the brain are? Look at the picture in the upper left.

Here is a schematic of the nervous system.

Nervous System Diseases

Here are the most common problems of the Nervous System:

Alzheimer's Disease:
Alzheimer's Disease causes slow memory loss and difficulties with language and emotions. The loss of these abilities is called dementia. As the disease advances, the person may need help bathing, eating, and going to the bathroom. The disease cannot be cured.

Multiple Sclerosis:
Multiple Sclerosis is a disease that occurs when the material around nerve cells in the middle nervous system is damaged. People with Multiple Sclerosis can have symptoms such as difficulties in walking, seeing problems, and pain. The word sclerosis comes from the Greek word "skleros," or hard. In many sclerosis, hard areas called "plaques" develop along the nerve. "Multiple" means the many different areas of the nervous system that may have damaged the nerve.

Huntington's Disease:
Huntington's Disease damages nerves in the area of the brain called the basal ganglia. Symptoms usually appear after age 30. They include dementia, random movements of the body, clumsiness, depression, memory loss and changes in mood. Although there are a few drugs that help with the symptoms, there is no treatment for Huntington's Disease and patients often die in about 15 years.

Parkinson's Disease:
Parkinson's Disease is a neurological disorder that affects mainly those people who are 60 years and older. Although there are drugs to control the symptoms of Parkinson's Disease (such as shaking arms and other movement problems), there is no known cause and no cure for this disease.

Parkinson's Disease happens when neurons lose the ability to function normally in a part of the brain called the substantia nigra. Many of these neurons connect to other neurons. This affects muscle control. Muscles contract and relax, causing shaking called tremors.