Pain Pathway

Question 1

What nerves are involved in pain sensation?

Answer 1

A myelinated and C unmyelinated

Question 2

What inflammatory processes are involved pain?

Answer 2

1. Primary activation - activated by cell damage. This triggers the release of potassium, bradykinin and prostaglandins.
2. Secondary activation - propagate to nearby terminals, stimulating the release of substance P. More bradykinin, histamine and serotonin.
3. Spread of hyperalgesia - Histamine and serotonin levels increase, sensitising nearby nociceptors.

Question 3

Which laminae do C-fibres go to?

Answer 3

Laminae III and IV

Question 4

Which laminae do A-myelinated fibres go to?

Answer 4

I & II

Question 5

Where does the neurotransmitter glutamate act?

Answer 5

The release of glutamate and substance P from nociceptor primary afferents activates AMPA and neurokinin-1 receptors on the post synaptic membrane. This results in sodium influx and second messenger activation.

This activates NMDA receptors

produces a sequence of secondary events in the cell, increasing the responsiveness of the nociceptive system.