We have cut ourselves. We have been burned. Or we have had headaches.
Some of us suffer pain rarely pain rarely. {{U}} {{U}} 1
{{/U}} {{/U}} Pain can take complete control of our body anal
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 13
meters a second. F. And they send the second, slower message of
pain to the brain.