Pain Flashcards
List 5 causes of pain
Inflammation
Neuropathy
Headache
Central pain (spinal cord injuries)
Cancer pain (tissue and nerve damage)
Which system of the brain attaches emotions to pain?
Limbic system
List 7 co-morbidities associated with pain
Difficulty sleeping
Lack of energy
Drowsiness
Difficulty concentrating
Anxiety
Poor appetite
Does the brain have pain sensors?
No, it is the only part of the body without pain sensors
What is nociceptive pain?
Pain from damaged non neural tissue, which activates nociceptors
Give an example of nociceptive pain
Lower back pain
What is neuropathic pain?
Pain caused by a lesion or disease of the somatosensory nervous system
Give 2 examples of neuropathic pain
Carpal tunnel syndrome
Trigeminal neuralgia
What is nociplastic pain?
Pain from nociceptors but no evidence of lesion of tissue damage
Give an example of nociplastic pain
Fibromyalgia
What are 6 factors that aid the transduction of pain from receptors?
5HT
Capsaicin
H+
Substance P
Prostaglandins
Na+ and Ca2+ channels
What are 6 factors that aid the transduction of pain from receptors?
5HT
Capsaicin
H+
Substance P
Prostaglandins
Na+ and Ca2+ channels
What receptors do Triptans target to block transduction of pain?
TRPV receptors that respond to heat - capsaicin
What receptors do CGRP antibodies target to block transduction of pain?
Substance P receptors that respond to mechanical stimulus
What receptors do NSAIDS target to block of pain?
Prostaglandin receptors that respond to cold stimulus
Why are NSAIDs always useful in treating pain?
NSAIDs reduce inflammation, and inflammation will always be a component of pain
What receptors does lidocaine target to block the transduction of pain?
Na+ and Ca2+ channels
Why is lidocaine not always useful?
It is non specific so may have other side effects as well as blocking pain
Give 2 examples of NSAIDs
Aspirin
Ibuprofen
Name the specific receptors that NSAIDs block
COX1
COX2
Cyclo-oxygenase
Why should patients be wary of stomach problems when taking ibuprofen?
Prostaglandins help production of stomach mucus, so blockage of this will make the stomach more susceptible to damage from stomach acid
Why does paracetamol function as an effective painkiller?
It targets receptors in the spinal cord and the brain
What is a negative factor of paracetamol?
It is metabolised quickly by the liver so has a narrow therapeutic window
Which pain blockers are effective for migraines?
Triptans
CGRP antibodies
Define hyperalgesia
More pain in response to a pain stimulus
Define allodynia
Over sensitivity of pain fibres resulting in pain from a non painful source
Name 2 calcium channel blockers that block the release of neurotransmitter
Gabapentin
Pregebalin
Name a potassium channel opener that increases outward currents of K+
Opioids
Name 2 sodium channel blockers that block the inward currents of Na+
Lidocaine
Carbamazepine
What is the disadvantage of taking calcium channel blockers for pain relief in the long term?
Can cause low blood pressure, resulting in negative effects on the heart - not good for the long term
Why is it advantageous to use NA+ blockers rather than Ca2+ blockers for pain?
There are many different specific Na+ channels, so easier to target specific channels for specific pain relief
Which Na+ channels are specific to C fibres?
NaV. 1.7+1.8
What happens to C fibres when they have repeated input?
It increases their sensitivity so they are hyper responsive to pain
Why does repeated input increase C fibre sensitivity?
The Mg2+ ion that blocks NMDA receptors is removed
What drug can be used to prevent increased C fibre sensitivity?
Ketamine
How does Ketamine prevent increased C fibre sensitivity?
It blocks the NMDA channels
What is brainstem analgesia?
When in a fight or flight response the PAG is activated so that pain is not detected at that time
How can mood affect pain?
Depressed patients complain of pain, they are linked
What is the mechanism of action of heroin?
It penetrates into the CNS and loses its acetyl groups, becoming morphine
On which receptors does heroin act on?
G protein coupled receptors
Where are the majority of receptors located which heroin acts on?
In the PAG
In the substantial gelatinosa
Which channels are opened by morphine and heroin?
K+ channels
Which channels are opened by morphine and heroin?
K+ channels
Name the 4 opioid receptors
Mu
Kappa
Delta
ORL-1
What is the natural neurotransmitter for Mu opioid receptors?
Endomorphins
What is the natural neurotransmitter for Delta opioid receptors?
Enkephalins
What is the natural neurotransmitter for Kappa opioid receptors?
Dynorphin
What is the natural neurotransmitter for ORL-1 opioid receptors?
Nociceptin
Name 2 drugs that act on Mu opioid receptors
Morphine
Pethidine
Name a drug that acts on Delta opioid receptors
DPDPE
Name a drug that acts on Kappa opioid receptors
U50488H
Which 3 opioid receptors conduct the opening of K+ channels?
Mu
Delta
ORL-1
Which opioid receptor conducts closure of Ca2+ channels?
Kappa
Name 2 pro drugs fro morphine
Heroin
Codeine
Which opioid is used for surgical procedures?
Fentanyl
What is an antagonist for opioid receptors?
Naloxone
What is an antagonist for opioid receptors?
Naloxone
Which fibres are not affected by opioids?
Alpha beta fibres
Can you still feel pain if alpha beta fibres are not inhibited?
No, you will be able to feel touch but not pain
How do opioid affect pre synaptic receptors?
They inhibit release of glutamate and peptide neurotransmitters
How do opioid affect pre synaptic receptors?
They inhibit release of glutamate and peptide neurotransmitters
How do opioids affect post synaptic receptors?
They hyper polarise the output neurone
How do opioids affect post synaptic receptors?
They hyper polarise the output neurone
List 4 side effects fo opioids
Respiratory depression
Anti-tussive (blocks cough reflex)
Constipation
Nausea and vomiting
What is the function of on cells in descending pathways?
They turn up the effect of pain
