Central Nervous System
The part of the nervous system that functions to coordinate the activity of all parts
of the bodies it contains the majority of the nervous system and consists of the
brain and the spinal cord. Together with the peripheral nervous system it has a fundamental
role in the control of behaviour.
The CNS is contained within the dorsal cavity, with the brain in the cranial cavity
and the spinal cord in the spinal cavity. The brain is protected by the skull the
spinal cord is protected by the vertebrae.[1]
The brain together with the spinal cord coordinates most voluntary movement and regulates
non-conscious processes.
The largest part of the brain is known as ‘the cerebrum’
Neurones - a nerve cell; it has a cell body, a very long axon sheathed in myelin,
and many tiny branches called dendrites. There are three kinds of neurones: sensory,
intermediate and motor neurones.
Axons - long cytoplasmic tubes, they carry electric impulses from one part of the
body to another. They are insulated from each other by their myelin sheathes.
Dendrites - tiny branches on the cell body and at the ends of all neurones. The dendrites
of one cell do not actually touch the dendrites of any other cell. There are very
tiny gaps between them called synapses.
Synapses - the gaps between the dendrites of one neurone and the cell body of another
one. There is no electrical connection between nerve cells. when one neurone stimulates
another it does so by secreting a chemical into the synapse.
Grey Matter - the material in the brain and spinal cord which contains the cell bodies
and dendrite of nerve cells. It is mainly cytoplasm. It appears grey to the naked
eye.
White Matter - the material in the brain and spinal cord which contains the axons
and myelin sheathes of nerve cells. It is mainly myelin which is a fat, so it appears
white to the naked eye
1. Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna
Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood
Cliffs, New Jersey, USA: Prentice Hall. pp. 132–144.
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