Medical  Explorer

Custom Search

Drugs A to Z  :  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  R  S  T  U  V  W  X  Y  Z
Medicinal Ingredients : A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

Beauty Products : A  B  C  D  E  F  G  I  M  N  O  P  R  S  T  V

Aging      Allergies     Alzheimer's      newArthritis    Asthma      newBacteria    Cancer    Chickenpox     Colds     Constipation      Diabetes      Epilepsy     Fatigue     Fever     Genetics       Haemorrhoids       Headaches      Hepatitis    newImmunity      Infection      Insomnia       Leprosy       Menopause      Obesity      Osteoporosis     Other Diseases    Pain      PMS     Parasites     Sinusitis     Stroke     Toxicology    Urology

<<Prev





Arthritis medications
Acupuncture
Alcohol
Patients
newGeneral Health
Medicinal food
Chinese medicine
Nutrients
Smoking
Vitamins
OTC Drugs
Health Products
Therapy
Symptom
Parasitology
 
 
The Nervous SystemThe Nervous System

The nervous system is the body's complex network of control and communications. Every time that you do anything -- literally anything -- your nervous system is intimately involved.

The nervous system is essential to our senses, the control of our movements (even automatic ones such as blinking or shivering), unconscious body functions such as digestion and breathing and the development of consciousness and thought.

The nervous system has two interconnected and interdependent parts. The central nervous system (which is often abbreviated to CNS) is the brain and spinal cord; the peripheral nervous system consists of all the nerve tissue outside the central nervous system.

The peripheral nervous system is further split into the somatic system and the autonomic system. The somatic system has two main functions. It collects information from the sense organs -- eyes, nose, ears, mouth and skin -- and coveys it to the CNS (the sensory system), and also transmits all of the signals from the CNS to the muscles which control movement (the motor system).

The purpose of the autonomic system is to regulate those internal organs and glands, such as the heart, stomach, kidneys and pancreas, that work without conscious effort.

BUILDING BLOCKS

The basic ingredient of the nervous system is a specialized cell called a neurone or neuron, which works in a similar way to wires in an electric circuit. It picks up a signal in one part of the body and carries it to another, where it may be passed on again or result in some action, such as the contraction of muscle fibres.

There are billions of neurones in the nervous system, but they are delicate cells, easily damaged or destroyed by injury, infection, pressure, chemical disturbance or starvation of oxygen. Neurones do not replace themselves, so such disorders tend to have serious consequences. Fortunately, people start out with an excessive number of neurones, so some wastage need have no effect.

There is another form of cell to be found in the nervous system. Neuroglia ('nerve glue') cells exist in large numbers and work to bind, protect, nourish and provide support for the neurones.

ANATOMY OF A NEURONE

Neurones come in various shapes and sizes, but they all have the same basic structure. Like all cells, they have a nucleus, contained in a roughly spherical part known as the cell body. From this project a number of short, fine, root-like fibres, called dendrites. The dendrites are the 'receivers' of the nervous system.

Each neurone also has a single, long fibre, the axon, which act as a 'transmitter'. At the end furthest from the cell body, axons branch into several tendrils, each ending in a number of knobs.

Each of these knobs lies close to, but does not actually touch, a dendrite from another neurone. Messages are transmitted across these gaps (which are known as synapses) by means of chemicals called neurotransmitters.

Axons can be anything from a fraction of a millimetre to a metre long, and are also known as nerve fibres. A loose bundle of such fibres which travel to a common location is called a nerve. Different nerves are said to 'supply' a particular area or organ. A few nerves -- such as the optic nerve to the eye -- are made up of sensory neurones alone, and others only of motor neurones; the majority, though, have both types.

Altogether, 43 pairs of nerves emerge from the CNS. Twelve of them connect directly to the brain, and are known as cranial nerves. The other 31 pairs are attached to either side of the spinal cord.

CRANIAL NERVES

The cranial nerves mainly supply the sense organs and muscles in the head, although a very important cranial nerve, the vagus, travels down the neck to supply the digestive organs, the heart and air passages in the lungs.

 

SPINAL NERVES

The spinal nerves emerge from the spinal cord at intervals, and supply all areas of the body below the neck. Each of the spinal nerves is attached to the spinal cord by means of two roots, one carrying motor fibres and the other sensory fibres. Each spinal nerve splits into a number of branches a short distance from the spinal cord.

     
     

New relief for neuropathic pain

Nerves from the brain

What is deep brain stimulation ?

Exercise to improve motor co-ordination

Dealing with Asperger's Syndrome

Anxiety

Attention deficit disorder 

Cerebral Palsy 

Dementia

Types of neurological disorders

Raynaud's Phenomenon

Managing multiple sclerosis

The shooting pain of sciatica

Beta blockers for essential tremor

The Body's Electrical Wiring

Multiple Sclerosis

Neuralgia

Panic attacks

The Nervous System

 

 

Abdomen
Blood
Bone
Breast
Ear

Eye

Face
Hair

Head

Heart
Kidney
Liver
Limbs
Lungs
newMind
Mouth
Muscles
Nails

Neck

Nerves
Nose

Skin

Teeth

Throat

Tongue
 
Health news
 
Cardiovascular Guide
 
Natural Remedies
 
Treatment of Cancer
 
Women's Health
 
Irritable bowel syndrome
 
Common Childhood Illnesses
 
Prescribed Drugs
 
 

     

 

Disclaimer