PBL 2 - Aches and Pains Flashcards
What is inflammatory, acute pain caused by?
Acute nociceptive pain due to muscular strain or other soft tissue injury
What pain travels down his leg?
Radicular
Define allodynia
Noxious sensation to non-painful stimuli
What is hyperalgesia?
Increased noxious perception to noxious stimulus
What is secondary hyperalgesia?
Hyperalgesia occurring outside the area of injury
What is peripheral sensitisation?
Increased sensitivity to afferent stimuli due to nerve and tissue injury
What inflammatory mediators are response for peripheral sensitisation?
Phospholipase A2
COX 1 + COX 2
Prostaglandins
How does phospholipase A2 cause sensitivity?
Releases arachidonic acid from cell membranes following injury
What do COX 1 and COX 2 do?
Uses arachidonic acid as a substrate for prostaglandin synthesis
What do prostaglandins do?
Affect ion channels
How do affected ion channels cause peripheral sensitisation?
Increase Na+ channel opening and increase in receptor presence
Also closing K+ channels reducing activation threshold and increasing responsiveness of nociceptors
How does central sensitisation occur?
Prolonged nociceptor input on dorsal horn
What do nociceptive afferents release in central sensitisation?
Glutamate and peptides
What do glutamate and peptides work on in central sensitisation?
NMDA
AMPA
What is gate theory?
Idea that thalamus and amygdala can prevent painful stimuli from occuring
Where do projections come from in gate theory?
Raphe nucleus
What do projections from raphe nucleus activate?
Inhibitory interneurones in laminae II
What do inhibitory interneurones in laminae II secrete?
GABA
ENK
What is the fast pain pathway also known as?
Neo-spinothalamic pathway
Which nociceptor is responsible for fast pain?
A delta
Where do A delta fibres synapse?
Laminae V
Where do A delta fibres decussate?
Spinal cord level
Where do A delta fibres travel?
Spinothalamic tract to ventral posterior lateral thalamus
Where does A delta fibres project to after ventral posterior lateral thalamus?
Somatosensory cortex 1 + 2 allowing for localisation and discrimination of pain
What is the slow pain pathway?
Paleo=spinothalamic pathway
What fibres are responsible for slow pain?
C fibres
Where do C fibres synapse?
laminae I + II
Where do C fibres decussate?
Spinal cord