The Human Brain

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The Human Brain


The human body is divided into many different parts called
organs.  All of the parts are controlled by an organ called the
brain, which is located in the head.  The brain weighs about 2.75
pounds, and has a whitish-pink appearance.  The brain is made up
of many cells, and is the control centre of the body.  The brain
flashes messages out to all the other parts of the body.  The
messages travel in very fine threads called nerves.  The nerves
and the brain make up a system somewhat like telephone poles
carrying wires across the city.  This is called the nervous
system.

The nerves in the body don't just send messages from the
brain to the organs, but also send messages from the eyes, ears,
skin and other organs back to your brain.  Some nerves are linked
directly to the brain.  Others have to reach the brain through a
sort of power line down the back, called the spinal cord.  The
brain and spinal cord make up the central nervous system.

The brain doesn't just control your organs, but also can
think and remember.  That part of the brain is called the mind.

                      PROTECTING THE BRAIN      


Twenty-eight bones make up the skull.  Eight of these bones
are interlocking plates.  These plates form the cranium.  The
cranium provides maximum protection with minimum weight, the
ideal combination.  The other twenty bones make up the face, jaw
and other parts of the skull.

Another way the brain keeps it self safe is by keeping
itself in liquid.  Nearly one fifth of the blood pumped by the
heart is sent to the brain.  The brain then sends the blood
through an intricate network of blood vessels to where the blood
is needed.  Specialized blood vessels called choroid plexuses
produce a protective cerebrospinal fluid.  This fluid is what the
brain literally floats in.

A third protective measure taken by the brain is called the
blood brain barrier.  This barrier consists of a network of
unique capillaries.  These capillaries are filters for harmful
chemicals carried by the blood, but do allow oxygen, water and
glucose to enter the brain.


THE DIFFERENT SECTIONS OF THE BRAIN


The brain is divided into three main sections.  The area at
the front of the brain is the largest.  Most of it is known as
the cerebrum.  It controls all of the movements that you have to
think about, thought and memory. The cerebrum is split in two
different sections, the right half and the left half.  

The outer layer of the cerebrum is called the cortex.  It is
mainly made up of cell bodies of neurons called grey matter.  
Most of the work the brain does is done in the cortex.  It is
very wrinkled and has many folds.  The wrinkles and folds give
the cortex a large surface area, even though it is squeezed up to
fit in the skull.  

The extra surface area gives the cerebrum more area to work.
Inside the cortex, the cerebrum is largely made up of white
matter.  White matter is tissue made only of nerve fibres.  

The middle region is deep inside the brain.  It's chief
purpose is to connect the front and the back of the brain
together.  It acts as a "switchboard", keeping the parts of your
brain in touch with each other.  

The back area of the brain is divided into three different
parts.  The pons is a band of nerve fibres which link the back of
the brain to the middle.  The cerebellum sees to it that all the
parts of your body work as a team.  It also makes sure you keep
your balance.  

The medulla is low down at the back of your head.  It links
the brain to the top of the spinal cord.  The medulla controls
the way your heart pumps blood through your body.  It also looks
after your breathing and helps you digest food.

THE DIFFERENT PARTS OF THE BRAIN

THE BRAINSTEM:

The brainstem is one of the oldest parts of the brain.   It
controls such functions as breathing, blood pressure, swallowing
and heart rate.  


THE HYPOTHALMUS:

This part of the brain is located directly above the brain
stem.  The hypothalmus controls basic drives like hunger and sex
and as

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