All of us have
felt pain. We have cut ourselves. We have been burned. Or we have had headaches.
Some of us suffer pain rarely. {{U}} {{U}} 1 {{/U}}
{{/U}} Pain can take complete control of our body and mind,
making it impossible to move and even to think. Yet we need pain. Without it, we
would not know if we have hurt ourselves. It is our body's warning system.
{{U}} {{U}} 2 {{/U}} {{/U}} Pain is the most
common reason we go to a doctor. It is the most common reason we take medicines.
Until recently, however, most doctors knew of only a few drugs that stopped some
pains. {{U}} {{U}} 3 {{/U}} {{/U}}But new knowledge about the
process of pain is helping them to control pain better.
Scientists have learned that the sense of pain is made up of both chemical and
electrical signals. {{U}} {{U}} 4 {{/U}} {{/U}}Scientists also
have learned that the nervous system sends two different kinds of pain messages
to the brain: one very fast, the other slow. The first message is the warning
signal. It moves at a speed of 30 meters a second. In less than a second, the
brain understands that part of the body is hurt and how badly it is injured.
{{U}} {{U}} 5 {{/U}} {{/U}}It tells us not to use the injured
part until it heals. A. And others have painful attacks all the
time. B. These signals travel from nerve cells in the injured
area, up the spinal cord (脊髓) to the brain, and back down again.
C. It tells us that we are injured and should do something about
it. D. They knew little about the process of pain
itself. E. The other message moves at a speed of only one meter
a second. F. And they send the second, slower message of pain
to the brain.