pain pathophysiology

Question 1

how is pain perceived

Answer 1

NOCICEPTORS (AFFERENT nerve fibers) – stimulated by noxious stimuli, info is taken to dorsal horn SENSORY, release pain neurotransmitters
2 types – Adelta Fibers – myelinated, localised, sharp pain
C fibers – unmyelinated, slow, poorly localised pain

Question 2

from the noxious stimuli, how is this processed

Answer 2

the 1ST ORDER NEURON is either the Adelta fibers or c fibers that go to the dorsal horn that release neurontransmitters (substance P) to activate the 2ND order neuron.
the 2nd order neuron goes to the anterior part of the grey matter to the spinothalamic tract. This brings the pain through the spinal cord towards the brain via spinothalamic tract, to the thalamus (RELAY STATION).
from the thalamus the THIRD ORDER NEURON
goes to the area of the pain where it is felt in the somatosensory cortex.

Question 3

how is the pain response inhibited (DESENDING PATHWAY)

Answer 3

from the periaqueductal grey matter to the nucleus raphe magnus and the synapse with the second neuron.
SEROTONIN NORADRENERGIC NEURON, releases serotonin
- inhibits the production of substance P
- stimulates INTERNEURON, releases enkephalin
(OPIOID), stops impulse to thalamus (ascending)