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Nervous System

NervesThe nervous system includes the brain, the spinal cord (Read about "The Brain" "The Spine") and the nerves that reach out to the rest of the body, acting as a two way street carrying information back and forth. The brain and spinal cord make up the central nervous system. The rest of the nervous system is called the peripheral nervous system.

The brain and the rest of the nervous system are composed of different types of cells, but the main one is a cell called the neuron. All sensations, movements, thoughts, memories and feelings are the result of signals that pass through neurons. The National Institute of Neurological Diseases and Stroke (NINDS) says neurons consist of three parts:

The neuron is usually surrounded by many support cells. Some types of cells wrap around the axon to form an insulating sheath. This sheath can include a fatty molecule called myelin, which provides insulation for the axon and helps nerve signals travel faster and farther. Axons may be very short, such as those that carry signals from one cell in the cerebral cortex to another cell less than a hair's width away. Or axons may be very long, such as those that carry messages from the brain all the way down the spinal cord. The longest axon in the body is the sciatic nerve, which goes from the base of the spinal cord all the way down the leg. The space between an axon and the dendrites of another neuron is called the synapse. Cells communicate with each other by sending chemicals into the synapse that are picked up by the next cell and passed on.

The spinal cord starts at the base of the skull and runs down the middle of the spinal column, inside the vertebrae. At each vertebra, nerves exit the spinal cord and reach out to the rest of the body. If the spinal cord is cut, by an injury or disease, the messages stop at the point of injury and the functions of the nervous system below that point stop.

The brain and spinal cord make up the central nervous system. The peripheral nervous system is the immense network of nerves that send and receive information from the brain and spinal cord to all other parts of the body. The peripheral nervous system is divided into two major parts: the somatic nervous system and the autonomic nervous system. The autonomic nervous system is further divided into three parts: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system.

The central nervous system is protected by the meninges and cerebrospinal fluid, but the peripheral nervous system does not have this kind of cushioning. Peripheral nerves are wrapped in myelin, however. Both parts of the nervous system are vulnerable to damage, and a wide range of diseases and complications can result.

Following the links below will give you more information on some conditions that affect the brain and nervous system, including mental health conditions.

Acoustic neuroma: see Balance Disorders

Addiction: see Addiction

Alzheimer's: see Alzheimer's Disease

Anencephaly: see Neural Tube Defects

Aneurysms: see Aneurysm

Anxiety disorder: see Anxiety

Aphasia: see Aphasia

Arachnoid cysts: see Arachnoid Cysts

Arteriovenous malformations (AVMs): see Vascular Lesions of the Central Nervous System

Asperger's disorder: see Autism Spectrum Disorders

Astrocytomas: see Brain Tumors

Attention deficit hyperactivity disorder: see ADHD

Autism: see Autism Spectrum Disorders

Balance disorders: see Balance Disorders

Bell's palsy: see Bell's Palsy

Bipolar disorder: see Depressive Illnesses

Birth defects: see Birth Defects

Brain anatomy: see The Brain

Brain stem gliomas: see Brain Tumors

Brain tumors: see Brain Tumors

Broca's aphasia: see Aphasia

Capillary telangiectases: see Vascular Lesions of the Central Nervous System

Cavernous malformations: see Vascular Lesions of the Central Nervous System

Cerebral palsy: see Cerebral Palsy

Charcot-Marie-Tooth disease (CMT): see Neuromuscular Diseases

Childhood disintegrative syndrome: see Autism Spectrum Disorders

Chronic pain: see Chronic Pain

Concussion: see Head Injury

Craniopharyngiomas: see Brain Tumors

Creutzfeldt-Jakob disease: see Creutzfeldt-Jakob Disease

Cysts, arachnoid: see Arachnoid Cysts

Cysts, spinal: see The Spine

Dementia: see Dementia

Depression: see Depressive Illnesses

Developmental disorders: see Autism Spectrum Disorders

Down syndrome: see Down Syndrome

Dyslexia: see Dyslexia

Dysthymia: see Depressive Illnesses

Dystonia: see Dystonia

Dystrophies: see Neuromuscular Diseases

EEG - electroencephalograph: see EEG - Electroencephalograph

Encephalitis: see Encephalitis & Meningitis

Encephaloceles: see Neural Tube Defects

Encephalopathy: see Encephalopathy

Epilepsy: see Epilepsy

Fainting: see Syncope (Fainting)

Fluent aphasia: see Aphasia

GBS (Guillain-Barre syndrome): see Guillain-Barre Syndrome

Germ cell tumors: see Brain Tumors

Global aphasia: see Aphasia

Guillain-Barre syndrome: see Guillain-Barre Syndrome

Headaches: see Headaches

Head injury: see Head Injury

Huntington's disease: see Huntington's Disease

Hydrocephalus: see Hydrocephalus

Inflammatory myopathies: see Neuromuscular Diseases

Lyme disease: see Lyme Disease

Mad cow disease: see Mad Cow Disease

Medulloblastomas: see Brain Tumors

Meningiomas: see Brain Tumors

Meningitis: see Encephalitis & Meningitis

Mental health: see Mental Health

Migraine: see Migraine Headaches

Motor neuron diseases: see Neuromuscular Diseases

Multiple sclerosis: see Multiple Sclerosis

Muscular dystrophies: see Neuromuscular Diseases

Myasthenia gravis: see Neuromuscular Diseases

Myopathies: see Neuromuscular Diseases

Nervous system: see Nervous System

Neural tube defects: see Neural Tube Defects

Neurofibromatosis: see Neurofibromatosis

Neuromuscular diseases: see Neuromuscular Diseases

Neuromuscular junction diseases: see Neuromuscular Diseases

Neuropathy: see Peripheral Neuropathy

Neuropathy, diabetic: see Diabetes

Neurosurgery: see Neurosurgery

Non-fluent aphasia: see Aphasia

Obsessive compulsive disorder (OCD): see OCD

Oligodendrogliomas: see Brain Tumors

Panic disorder: see Panic Disorder

Paresthesia: see Paresthesia

Parkinson's disease: see Parkinson's Disease

Peripheral nerve diseases: see Neuromuscular Diseases

Peripheral neuropathy: see Peripheral Neuropathy

Pervasive developmental disorders: see Autism Spectrum Disorders

Phobias: see Phobias

Pineal region tumors: see Brain Tumors

Post-polio syndrome: see Post-Polio Syndrome

Postpartum depression: see Depressive Illnesses

Post-traumatic stress disorder (PTSD): see PTSD

Prion diseases: see Encephalopathy

Rett syndrome: see Autism Spectrum Disorders

Schizophrenia: see Schizophrenia

Schwannomas, brain: see Brain Tumors

Seasonal affective disorder (SAD): see Depressive Illnesses

Seizures: see Seizures

Shaken baby syndrome: see Head Injury

Shingles: see Shingles

Social phobia: see Social Phobia

Spina bifida: see Neural Tube Defects

Spine: see The Spine

Stroke: see Stroke

Stuttering: see Stuttering

Suicide: see Suicide Prevention

Syncope: see Syncope (Fainting)

Tay-Sachs disease: see Tay-Sachs Disease

TIA's: see Stroke

Tourette syndrome: see Tourette Syndrome

Transmissible spongiform encephalopathies (TSE): see Encephalopathy

Traumatic brain injury: see Head Injury

Tumors, brain: see Brain Tumors

Tumors, spine: see The Spine

Venous malformations: see Vascular Lesions of the Central Nervous System

Vertigo: see Balance Disorders

Vestibular schwannoma: see Balance Disorders

Wernicke's aphasia: see Aphasia

Wilson's disease: see The Liver

All Concept Communications material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.

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