Pain Flashcards
What is pain
An unpleasant sensory and emotional
experience associated with actual or potential
tissue damage, or described
in terms of such damage
What pain do we feel on a daily basis
Acute (nociceptive) pain
What characterises ‘normal pain’
Only elicited when intense/noxious stimuli
threaten to damage normal tissue - INDUCED
- Has an adaptive/biologically useful role:
Serves as a protective function - Characterised by a high threshold and
a limited duration - Afferents: Aδ and C-fibres
What fibres create a sharp stabbing pain
A delta
What fibres are responsible for a dull aching (2nd) pain
C fibres
What are the features of nociceptor endings
Free nerve endings
High threshold of activation
Respond to intense (noxious) stimuli usually associated with pain
-A delta: noxious mechanical/heat
-C fibres: polymodal
Carry several types of receptor proteins - responsive to different noxious stimuli
Display sensitisation
Where does the 2nd order sensory neurone project into in the spinothalamic pathway
Antero-lateral funiculus (white matter)
Where does the 2nd order neurone give off little colateral branches
Medulla (2)
Pons (2)
Midbrain (2)
How do we feel pain in our teeth
Free nerve endings in dentine of the tooth send axons via trigeminal nerve to spinal nucleus up to thalamus and then to sensory cortex
What receptors are found in pain pathways
Nociceptors
What are the names of the pain pathways
Spinothalamic
Anterior (ventral) trigemino-thalamic
Where in the brain do pain signals go
Primary sensory cortex
Subcortical areas
What are the advantages of pain
- Location
- Pain quality – sharp stabbing, dull ache
- Pain intensity
- Frequency / duration
- Provoking / relieving events
What are referred pains
These are perceived in one part of the
body, but the pathology is elsewhere
Pain tends to refer from an internal
organ to a superficial area e.g. skin
What causes referred pain
Referral due to a convergence of
inputs in the CNS
Pains tend to be referred to sites of
common embryological origin
Where can referred heart pain be felt
Left chest, shoulder and heart
What factors affect a persons pain perception
Tissue damage
Genetic
Molecular
Cellular
Anatomical
Physiological
Psychological
Social
What external factors can affect pain tolerance
Psychological
-sex
-age
-cognitive level
-culture
Situational
-expectation
-control
-relevance
Emotional
-fear
-anger
-frustration
What can block the pain signals
Inhibitory Interneurons stimulated by things such as rubbing a burn
What is the supraspinal loop
Group of cells which relay information back down from the PAG to meddula and to spinal chord inhibiting second order neurones or reduce receptor activity
Reduced feeling of pain
What 5 pillars are associated with tissue damage
heat
redness
swelling
pain
loss of function
What is the triple response to mild trauma
Wheal
Red reaction
Flare
What causes the wheal
Release of bradykinin
What causes the dilation of blood vessels and what response is this
CGRP dilates blood vessels causing a flare
