Pain Flashcards
Where is motor and touch information sent to?
Mid brain
Where is pain information from?
Around spinal cord
What is nociception?
Sensing a stimulus that evokes pain
Pain can be chemical, mechanical or thermal. What is the difference between pin prick pain and deep/true pain?
Deep pain is more extreme
What causes ion channels to open when experiencing chemical, mechanical and thermal pin prick pain?
Chemical - ion channels open with chemicals
Mechanical - ion channels open with movement
Thermal - temperatures activate distinct thermal nociceptors
pain is usually detected by what part of a nerve?
Free nerve endings
What are transient receptor potential channels
Ion channels that are activated by inflammation, injury, molecules found in spices or cooling agents, pressure, stretch etc
Give an example of a molecule found in spice that activate transient receptor potential channels (TRPs)
Capsaicin
Give an example of a cooling agent that activates transient receptor potential channels
Menthol
What are the 4 main types of nerve fibres?
A alpha
A beta
A delta
C fibres
Which are the fastest and slowest nerve fibres?
A alpha fastest
C fibres slowest
Why are C-fibres slowest?
Unmyelinated - cannot do saltatory conduction
Grey matter has layers. What are these called, how many are there?
Laminae
I to X
What is the second layer/lamina of grey matter called?
Substantia gelatinosa
What is in lamina II?
Substance p - acts as neurotransmitter
What is the receptor to substance P
NK1 (neurokinin 1)
What are the types of ascending pain pathways?
Ventrolateral (includes spinothalamic and spinoreticular)
Spinocervicular
Where does the spinothalamic tract go? What stimuli does it detect?
Spine to thalamus
Detects pinprick and thermal stimuli
Where does the spinoreticular tract go? What stimuli does it detect?
Spine to reticular formation
True pain
Where does the spinocervicular tract go? Which species does not have this tract?
From thalamus sub nuclei, through cerebellum through medial meniscus, lateral cervical nucleus
Humans
What activates the vomiting centre?
Pain
Vestibular apparatus
Chemoreceptor trigger zone
What are the exceptions to the rule that pain = nociception?
Phantom limbs
Pain gate
Referred pain
Hyperalgesia
What is the pain gate?
Certain stimuli (e.g. stress) can switch off the ascending signal and cannot reach the CNS
What is referred pain?
Pain is felt in different place to actual injury
What are the 2 causes of referred pain?
Ascending fibres packed so close together that brain cannot distinguish the source
Several nociceptive fibres synapse on the same ascending fibre
What causes phantom limb pain?
Nociceptive fibres synapse on same ascending fibre
Also denervated fibres can re-innervate other tissues
What causes hyperalgesia?
Local inflammation
Spinal cord re-wiring
What can be used in research to asses pain threshold?
Von Frey Hairs
