The human body is divided into many different parts called .
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 .
