The Nervous System

THE NERVOUS SYSTEM

Humans have a complex nervous system with a brain, which is large in proportion to our body size. The nervous system performs three basic functions;

1.  it receives, stores and analyses information from sense organs such as the eyes and ears, making us aware of our environment.

2.  it controls the physiological activities of the body systems and maintains constant conditions (homeostasis) within the body.

3.  it controls our muscles, enabling us to move and speak.

The structure of the nervous system

1.  Central Nervous System (CNS) – consists of the brain and spinal cord

2.  Peripheral Nervous System (PNS) – is composed of 12 pairs of cranial nerves and 31 pairs of spinal nerves which connect the CNS with sense organs, muscles and glands

3.  Autonomic Nervous System (ANS) – this describes certain peripheral nerves that send impulses to internal organs and glands

Word root / Combing form / Meaning
Neur / Neur/o / nerve

Neurones are the basic structural units of the nervous system. They are specialised cells, for the transmission of nerve impulses. There are three basic types of neurone; sensory, motor and connector.

Activity 1 write the meaning of;

1.  neurology ______

2.  neuropathy ______

3.  neurohistology ______

4.  polyneuritis ______

5.  neurospasm ______

Word root / Combining form / Meaning
Plex / Plex/o / Network of nerves
Cephal / Cephal/o / Head
Encephal / Encephal/o / Brain
Cerebr / Cerebr/o / The cerebral hemispheres or cerebrum of the brain

Activity 2 write the meaning of;

1  Cephalalgia ______

2  Cephalocele ______

3  Hydrocephalus ______

4  Anencephalic ______

5  Electroencephalograph ______

Build words which mean;

6  x-ray picture of the head ______

7  pertaining to a very small head ______

8  tumour of a nerve ______

9  hardening of a nerve ______

10  person who specialises in the study of nerves and their disorders ______

Cerebro-vascular accident (CVA)

Disorders within blood vessels of the cerebrum can result in a stroke or apoplexy. Reduction of blood flow (ischaemia) within the cerebrum causes cells to die due to lack of oxygen and nutrients. As cells in this area control movements of many parts of the body, paralysis of limbs and loss of speech are common symptoms of CVA’s. The severity of symptoms depends of the area of brain tissue damaged. Sometimes there is recovery and the patient is left with slight paralysis.

The cerebral cortex

The outer layer of the cerebrum is known as the cerebral cortex. It is extensively folded into fissures, giving it a large surface area. This part of the brain contains motor and sensory areas and is the site of consciousness and intelligence.

Word root / Combining form / Meaning
Ventricul / Ventricul/o / Ventricle
Crani / Crani/o / Bones of the skull
Gangli / Gangli/o, ganglion / Swelling – knot of nerve body
Mening / Mening/o, mening/i / Membrane
Radicul / Radicul/o / Spinal nerve roots
Myel / Myel/o / Marrow
Pleg / -plegia / Blow or stroke
Aesthesi / Aesthesi/o, aesthesia, aesthetic / Perception of sensation
Narc / Narc/o / Stupor – abnormally deep sleep induced by a drug
Alges / Algesi/o, -algesia / Sense of pain
Rachi / Rachi/o / spine

Activity 3 write the meaning of;

1  Postganglionic ______

2  Meningioma ______

3  Epidural ______

4  Subdural haematoma

______

Build words which mean;

5  Incision into the skull ______

6  Condition of softening of the skull ______

7  Inflammation of the meninges ______

Rachiocentesis is performed to obtain a sample of cerebrospinal fluid (CSF) from the subarachnoid space in the lumbar region of the spinal cord. This procedure is commonly known as a lumbar puncture or spinal tap. Damage to the brain or spinal cord can result in loss of movement in varying degrees, to different parts of the body. There can be paralysis of limbs, paralysis of right or left side of the body, or paralysis of various activities such as speech. The term paraesthesia is used to mean any abnormal sensations, such as ‘pins and needles’.

Activity 4 write the meaning of;

1.  Quadriplegia ______

2.  Hemiplegia ______

3.  Paraplegia ______

4.  Anaesthesia ______

5.  Anaesthetic ______

6.  Anaesthesiology ______

7.  Anaesthesiologist ______

8.  Analgesia ______

9.  Analgesic ______

10. Narcosis ______

THE NERVOUS SYSTEM 4