6.1 - Neural Basis of Pain Flashcards
Which spinal system is associated with Pain?
Anterolateral system
What are the 2 types of nociceptors and what simulus do they detect?
A(delta) - Mechanical
C - Mechanical, thermal, chemical
Describe the nerve endings of the nociceptors
Naked nerve endings
Describe how a lesion in the skin (a cut) causes activation of nociceptors and the immediate after effects
Cut in the skin results in cells releasing their contents (including K+, histamine, H+, bradykinin and prostaglandins) which then migrate to the nociceptor axon and activate it. Substance P is released from nerve endings of nociceptor which increases capillary permeability and contributes to inflammation.
How do NSAIDS and steroids work as an analgesic
NSAIDs and steroids are COX inhibitors that prevent the formation of prostaglandins which act to activate nociceptors
Describe the features of the A(delta) fibres
Sharp stabbing pain
well localised,
first pain felt
lower threshold
initiates withdrawal reflex
Describe the features of the C nociceptor fibres
Dull throbbing pain
poorly localised
second pain
higher threshold
tissue damage occurring
How do local anasthetics e.g. lidocaine work to stop pain?
lidocaine is a voltage dependent Na channel blocker, stops transmission along the axon fibre by not allowing AP to propagate
What lamina of the grey matter does the substantia gelatinosa refer to?
Lamina 2
What lamina of the grey matter are A(delta) fibres found in?
1 and 5
What lamina of the grey matter are C fibres found in?
1, 2 and 5
What lamina of the grey matter are A(beta) fibres found in?
3, 4 and 5
What is central modulation in relation to the pain system?
There is an inherent modulatory system where the brain can use endogenous opioid peptide analgesiscs and other neurotransmitters to block pain responses
Name 2 opioid neuropeptides involved in endogenous analgesics
endorphins, enkephalins
Name an antagonist and 2 agonists of opiate receptors
agonists - morhpine, codeine
antagonists - naloxone
