Page 73 - BBC Focus - August 2017

THE PAIN PATHWAY
From the initial trigger to the feeling of ‘ouch’, the
whole process takes only a matter of milliseconds

1. Specialised sensory receptors
called nociceptors detect the
painful stimulus, converting
it into an electrical signal.
There are different nociceptors
for different stimuli: heat,
mechanical, chemical/acid, and
cold. Some detect more than
one type of stimulus.

Heat
3. A network of
many brain regions
is involved in
processing the signal.
The perception of
pain emerges from
Chemical/acid this complex activity.

2. The signal travels
along two types of pain
nerve fibre to the spinal
cord. A-delta fibres carry
the sharp, rapid pain,
Mechanical
while C fibres carry the
slow, dull ache. Signals
are modulated in the
spinal cord before being
sent to the brain.

Cold

WHAT WE STILL DON’T KNOW

HOW WE DETECT WHY PEOPLE DEVELOP WHERE THE ‘HURT’
1 A PINPRICK 2 CHRONIC PAIN 3 IS IN PAIN
Using molecular biology and various In chronic pain, the A-delta and C fibres It’s thought that Oscar Wilde once
natural chemicals as ‘probes’, we’ve often switch on permanently, causing said: “I don’t mind pain, so long as it
identified most of the nociceptors in the non-stop agony. If we can work out why doesn’t hurt”. Funny, yet spot on. We
body that respond to painful events. this happens and manage to prevent it, know that the perception of hurt emerges
ILLUSTRATION: ACUTE GRAPHICS nociceptor that detects a painful millions of sufferers. Also, we still need to activating together, but we still don’t
from a network of brain regions
However, we’re still missing the
we’ll have gone a long way to helping
understand why, after the same injury,
hammer blow, knife cut or pinprick.
know exactly how this activity produces
Several research groups are on the hunt
the ‘hurt’ of pain. Brain imaging should
one person can develop chronic pain, but
for this elusive nociceptor.
the other person does not.
tell us more…
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