Pain and nociception L9 Flashcards
Pain=
unpleasant sensory and emotional experience associated with actual or potential damage (subjective response)
Nociception=
The neural processes of detecting, encoding and processing noxious stimuli
(physiological response)
pain based on origin can be; (2)
Somatic
Visceral
Visceral pain=
organs of thorax and abdominal cavity
Somatic pain=
superficial or/
deep
Superficial pain=
sharp brief pain (pinching)
Based on duration pain can be either
chronic or/
acute
Chronic pain= (3)
persists
ill defined onset
poorly treatable
Acute pain= (3)
resolves when injury heels
adequately treatable
recent well defined onset
nociception involves
PNS and CNS
nociceptors=
sensors found in most body tissues that respond to noxious stimuli
Nociception is separate to
somatosensory
Where has no nociceptors
the brain
What two things are nociceptors characterised by
axon properties
receptor channels
What is special about the end of nociceptors
unspecialised (free) nerve endings
Types of nociceptors
thermal mechanical Chemical Polymodal Sleeping/ silent
What are polymodal nociceptors
include thermal, mechanical, chemical stimuli
What are sleeping/ silent nociceptors
inflammation, only once injury has occurred
What fibres are large diameter, rapidly conducting
A alpha and A beta
What receptors are associated with A alpha and B beta
Low threshold mechanoreceptors
Small diameter, slow conducting afferents=
A delta and C fibres
What are A delta associated with
nociceptors and thermo-receptors
What are C fibres associated with
polymodal nociceptors
What is first pain (4)
Sharp or prickling
fast A delta fibres
Mechanical or thermal nociceptors
rapid and short
what is second pain (4)
dull, aching, burning
Slow C fibres
slow onset and long duration
Polymodal nociceptors
what neurotransmitters are associated with nociception
glutamate and substance P
What do gene mutations in Na+ channels (specific to nociceptors) lead to
congenital analgesia
What is cogenital analgesia
insensitivity to pain (internally and externally)
Which is the nociceptive pathway
spinothalamic pathway
where do sensory inputs from the spinothalamic pathway decussate
2 levels up on the spinal cord (ascend on opposite side)
In the spinothalamic pathway where does the information travel from the medulla
to the thalamus—-> then to the somatosensory cortex
What causes our emotional response to pain
side pathways to the hypothalamus and limbic system
What causes our alertness from pain
reticular formation
Where does the DCML pathway decussate
in the medulla
What does the DCML pathway carry signals off
Touch,
vibration
proprioception
Where does pain from the face and head enter the pons
cranial nerves 5,7,9 and 10
What is the tract for face pain called
spinal trigeminal tract
What fibres is tooth pulp innervated by
c and A delta fibres
What causes referred pain
convergance of nociceptor inputs from viscera and skin
Where is heart pain referred
chest and left arm
Where is early appendicitis referred to
abdominal wall
What is a phantom limb
sensation that a missing limb is still attached to the body and moving appropriately
what is phantom limb pain
chronic pain in phantom limb
Treatment for phantom limb pain
mirror therapy
stump stimulation
what is gate theory
co-activation of A alpha/ beta (not nociceptors) suppresses activation of C fibres (nociception)
Where is perception of pain modulated
higher brain centres
What can suppress pain
strong emotions, stress, stoic determination
Dissociation=
central modulation of pain
Hyperalgesia=
increased pain sensitivity (reduced threshold)
Caused by C afferents —> stimulus that normally evokes pain
allodynia=
touched evoked pain
caused by Beta afferents (stimulus that does NOT normally evoke pain. )
What can induce hyperalgesia
the sensitisation of peripheral nociceptors; by tissue damage/ inflammation releasing substance P, histamine ect
primary hyperalgesia
occurs at the site of tissue damage
secondary hyperalgesia
occurs around the site of tissue damage
What is fibromyalgia
medical disorder characterised by chronic widespread pain and allodynia
symptoms of fibromyalgia
fatigue
difficulty sleeping
muscle stiffness
IBS
Treatment for fibromyalgia
analgesics
antidepressants
exercise
counselling
back pain
is the number one cause of disability in Britain
Pharmacological pain treatment overview
opioids
NSAID
Local anaesthetics
Psychotropic drugs
What do Opioids produce
analgesia (pain relief)
where do opioids bind
to opioid receptors in the brain
Three types of opioid receptors
Mu
Delta
Kappa
6 clinical analgesics
Morphine Diamorphine (heroin) Codeine Fentanyl Pethidine Tramadol
When not have to morphine
acute respiratory depression
