DISEASES OF THE NERVOUS SYSTEM.

 

INTRODUCTION

The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body.The nervous system includes both the Central nervous system and Peripheral nervous system. The Central nervous system is made up of the brain and spinal cord and The Peripheral nervous system is made up of the Somatic and the Autonomic nervous systems.

 The Brain

The brain lies within the skull and is shaped like a mushroom.  The brain consists of four principal parts:

• the brain stem
• the cerebrum
• the cerebellum
• the diencephalon

The brain weighs approximately 1.3 to 1.4 kg. It has nerve cells called the neurons and supporting cells called the glia.
There are two types of matter in the brain:  grey matter and white matter.  Grey matter receives and stores impulses.  Cell bodies of neurons and neuroglia are in the grey matter.  White matter in the brain carries impulses to and from grey matter.  It consists of the nerve fibers (axons).

The Brain Stem
The brain stem is also known as the Medulla oblongata. It is located between the pons and the spinal cord and is only about one inch long.

The Cerebrum
The cerebrum forms the bulk of the brain and is supported on the brain stem.  The cerebrum is divided into two hemispheres.  Each hemisphere controls the activities of the side of the body opposite that hemisphere.
The hemispheres are further divided into four lobes:

• Frontal lobe
• Temporal lobes
• Parietal lobe
• Occipital lobe

The Cerebellum This is located behind and below the cerebrum.

The Diencephalon
The diencephalon is also known as the fore brain stem. It includes the thalamus and hypothalamus. The thalamus is where sensory and other impulses go and coalesce.
The hypothalamus is a smaller part of the diencephalon

Most mental diseases arise as a result of malfunctioning of brain cells; May be due to:-

i.                   Drug abuse.

ii.                  Brain infection.

iii.                A child born with brain defects.

iv.              Accidents that damage the brain.  .

Diseases of the nervous system.

1.      Meningitis: Is an infection of the Meninges (The membrane that cover the brain and spinal cord). Is caused by bacteria or virus.

2.      Psychosis: Is a disorder that result from self-edification or fear. Person imagines that there are unknown people who want to kill him or her.

-Psychotic must be referred to psychiatrist for treatment.

3.      Epilepsy: Is due to scar or damage of brain. It leads to periodical loss of consciousness accompanied by fits or convulsions, ie. Violent contractions of the skeletal muscles.  The disease is inheritable. Many cases of epilepsy can be controlled by medication, allowing the victims to lead normal lives.

4.      Leprosy: Is a bacterial disease which affects nerves in the limbs, it may also affect the iris. It causes painful white patches to appear on the skin and destroys the nerves.

5.      Tetanus: Is a bacterial disease which damage the nerves. The Tetanus bacillus found in the soil, penetrates through wounds. It causes muscular spasm followed by a generalized convulsion.

-Prevention: by immunization and rest.

6.      Poliomyelitis: Is a viral disease, the patient becomes paralyzed in the affected region. Immunisation is necessary.

7.      Stroke: Is a sudden serious illness in the brain that can cause loss of the power to move or to speak clearly. This may be due to damage or blockage or bursting of the brain artery.

8.      Schizophrenia. Is a mental illness in which person is unable to link his or her thoughts to the real life. One suffers from delusion and life or imagination.

9.      Nervous breakdown. A mental problem affecting the brain due to worry or over working. The victim is over whelmed by feeling of despair or depression.

10.  Neurosis: Is a mental problem that cause an abnormal behavior, ie. Strong worry or fear (phobias) which he or she wants to over come. Eg. Obsession of being clean, where one washes hands continuously in fear of contamination.

11.  Cerebral malaria. Is a protozoan disease caused by various types of plasmodium, eg. Plasmodium  malariae/vivax/falciparum/ovale. When these parasites reach central nervous system will cause severe inflammation of meninges covering the brain.

-Signs: high fever, severe headache, vomiting, restless and begins to behave abnormally.

12.  Parkinson’s disease. Is a disorder mostly found in elderly people. It affects the cerebral cortex that controls the activity of skeletal muscles. This result in rigid joints and uncontrollable trembling. It can be controlled by medication.

13.  Alzheimer’s disease. Is a progressive and incurable disease which occurs in some people past the age of 50. It is characterized by forgetfulness and confusion. During the forgetfulness phase, there are annoying problems of learning and memory. The victim easily forgets.