pain Flashcards
what is the definition of pain?
an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
what is the most common type of pain?
acute nociceptive pain
when do we feel acute nociceptive pain?
when intense/noxious stimuli threaten to damage normal tissue- induced sensory reception
why do we have acute pain?
protective function
what is the perception of pain characterised by?
- high threshold
- limited duration
what are the afferent axons which mediate pain?
- alpha delta fibres
- c fibres
what type of pain corresponds to the a delta fibres?
sharp stabbing pain (first)
what type of pain corresponds to the c fibre activity?
dull aching pain (second pain)
what are the main features of nociceptor endings?
- free nerve endings
- high threshold of activation
- respond to intense (noxious) stimuli usually associated with pain
- carry several types of receptor proteins, each responsive to different noxious stimuli
- display sensitisation (more we use, easier to recruit)
which fibres respond to noxious mechanical/heat stimuli?
a delta
which type of fibres respond to polymodal stimuli?
c fibres
describe the neuron path of the spinothalamic pathway?
- a delta/c fibres from pain source in periphery to dorsal horn
- 2nd neuron- axon crosses to other side of spinal cord to antero-lateral funiculus and up to the thalamus (through medulla, pons, midbrain, spinal lemniscus)
- 3rd neuron- from thalamus to cerebral cortex
describe the neuron path of the spinothalamic pathway?
- a delta/c fibres from pain source in periphery to dorsal horn
- 2nd neuron- axon crosses to other side of spinal cord to antero-lateral funiculus and up to the thalamus (through medulla, pons, midbrain, spinal lemniscus)
- 3rd neuron- from thalamus to cerebral cortex
what is the spinothalamic tract?
projection up the spine through the antero-lateral funiculus
what questions should be asked when diagnosing pain?
- location
- pain quality (sharp/dull)
- pain intensity
- frequency/duration
- provoking/relieving events
what are refferred pains?
- perceived in one part of the body, but the pathology is elsewhere
- pain usually refers from an internal organ to a superficial area eg skin
- referral due to a convergence of inputs in the CNS
- pains tend to be referred to sites of common embryological origin
what are factor categories which can influence our perception of pain?
- genetic
- psychological
- situational
- emotional
what does rubbing the affected area of pain activate?
a beta fibres which can activate a population of inhibitory intraneurons which inhibit the 2nd order neurons to block the perception of pain
what is the function of the supraspinal loop?
dampening down activity in dorsal horn to reduce pain
what are the 5 signs of inflammation?
- heat
- redness
- swelling
- pain
- loss of function
white reaction
how can pain be modulated?
local analgesics in the nerve endings of the 1st neuron
