CANCER - The Brain - Structure and Functions |
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Between the surfaces of the brain
and the skull surrounding it there are three layers of membrane called the meninges which
completely cover the brain and spinal cord (see diagrams).
Between two of these layers is the subarachnoid space, which contains a fluid called cerebrospinal fluid The brain, together with the spinal cord, makes up the nerve control centre which controls our body's functions. The brain's nerve cells: Like every other organ in the body, the brain is made up of cells. The basic cell of the brain is the nerve cell or neurone, and there are about 40 billion of these in a brain. You are born with this amount and unlike other cells they do not replace themselves. In fact, through adult life there is a gradual decrease in the number of these cells. The nerve cells communicate with each other and other parts of the body by sending messages (nerve impulses) through a system of nerve pathways. Nerve impulses are similar to electrical currents and can be switched on or off by the body. The nerve cells communicate with each other and other parts of the body by sending messages (nerve impulses) through a system of nerve pathways. Nerve impulses are similar to electrical currents and can be switched on or off by the body. The nerve cells are supported by a different family of cells called the glial cells. These are astrocytes, oligodendrocytes and ependymal cells. Main structures and functions of the brain The main parts of the brain are the cerebrum (the forebrain) containing the right and left cerebral hemispheres; the cerebellum (the hindbrain); and the brain stem. Cerebrum -- This is the largest area of the brain and is concerned with all higher mental functions. It is made up of two cerebral hemispheres or halves. The right cerebral hemisphere controls the left side of the body and the left cerebral hemisphere controls the right side of the body. Each cerebral hemisphere is divided into four lobes: frontal, parietal, temporal and occipital. Each lobe controls a different range of activities. Cerebellum -- This is the part of the hindbrain concerned with movement and balance. These activities are carried out below the level of consciousness and are not under a person's control. Brain stem -- The brain stem controls the basic functions of blood pressure, breathing, heart beat and also eye movements and swallowing. It is the bottom part of the brain and connects the cerebral hemispheres with the spinal cord. |
