Flashcards in Pain Deck (19):
What are the two classes of pain sensation
adaptive, protective pain
- nociceptive pain
- Inflammatory pain
Maladaptive, pathological pain
- neuropathic pain
- functional pain syndrome
What are the responses to nociceptor activation?
pain - higher order cortical process -> learn about things that might hurt us
withdrawal reflex - spinal cord reflex
What are the 2 nociceptor fibre types?
C Fibres and Adelta fibres
What are the characteristics of C fibres? where do they project?
fine diameter and NO myelin ("See them bc their naked"), dorsal rexed laminar (regions 1 & 2) of the dorsal horn -> slower burning/throbbing pain.
What kind of fibre types are the cutaneous (meissner, etc) mechanoreceptors?
What are the features of the A-delta fibres - what info do they carry?
myelinated, fine diameter, med-fast transmission to both dorsal and ventral rexed lamina of the dorsal horn (regions 1 and 5) - initial SHARP pain
What happens to receptor firing when stimuli is removed from touch receptors vs nociceptors?
touch = stops firing, nociceptors continue to fire if tissue has been damaged
Where are Adelta and C fibre nociceptors found?
hairy skin = both, glabrous skin only has C fibres
What two things are altered in Inflammatory pain?
altered pain sensitivity & spontaneous pain
Describe the process of peripheral sensitisation
What is hyperalgesia?
an increased response to a normally painful stimulus -> accentuated feelings of pain -> change in stimulus intensity
What is allodynia?
a painful response to a normally innocuous stimulus -> change in threshold
What is central sensitisation?
What is neuropathic pain? What happens in peripheral neuropathic pain?
pain due to a neural lesion and damage to the somatosensory system eg brachial plexus avulsion, strokes or MS.
peripheral: - fibres generate pain signals without stimulation
What is dysfunctional pain?
pain which is due to no identifiable pathology ->eg migraine, fibromyalgia
What is the descending pathway that modulates pain?
periaquaductal grey, rostroventral medulla
How does affective responses (emotional state) influence pain perception?
natural threat/stimulus (ie cat for a mouse) causes hypoalgesia as part of the fear response -> amygdala sends signals to the PAG. Expectations of pain can increase pain sensations felt
the spinoparabrachial tract transmits signs from nociceptors to where?
limbic centre -> emotional/aversive perception