Pain and analgesia Flashcards
Pain?
“An unpleasant sensory and emotional experience, associated with actual tissue damage or described in terms of such damage”
What are the 3 classified pain? with example of fire alarm
(i) Nociceptive (acute/sharp) pain (e.g. pin prick, visceral distension)
(ii) Inflammatory (prolonged) pain (e.g. sunburn, inflamed wound)
(iii) Pathological pain
Nociceptive pain begins with the activation of —–
nociceptors
about nociceptors?
Nociceptive pain is —- ; serves as an early warning system to detect and minimise contact with damaging stimuli (noxious events)
Nociceptive pain is —- threshold – provoked only by intense stimuli that activate nociceptors
adaptive
high
Nociceptors are —– order neurons that relay information to second order neurons in the CNS by chemical synaptic transmission.
first
what is the benefit of nociceptive pain?
- initiates a withdrawal reflex
- is extremely unpleasant
- engages adverse emotional components
- serves to inscribe memories that allow avoidance of harm in the future
Inflammatory pain?
Pathological pain?
what mutation causes the absence of pain?
in the gene SCN9A that encodes a particular voltage-activated Na+ channel (Nav1.7) that is highly expressed in nociceptive neurons
Nociceptors are —– —– neurons innervating peripheral tissues—activated only by mechanical, thermal, or chemical stimuli that are noxious. Comprise —– and —–fibres.
primary afferent
mechanical
thermal
chemical
noxious
Aδ
C
Aδ?
fibres are mechanical/thermal nociceptors that are thinly myelinated (conduction velocity of 6-30 ms-1 ) & respond to noxious mechanical and thermal stimuli. Mediate ‘first’, or fast, pain.
C-fibres?
C-fibres are nociceptors that are unmyelinated (conduction velocity of 0.5 – 2.0 ms-1) – collectively they respond to all noxious stimuli (i.e. they are polymodal). Mediate ‘second’, or slow, pain
Aδ vs C fibre?
examples of stimuli that activate the peripheral terminals of polymodal nociceptors