Physiology of Pain Flashcards
why is pain difficult to asses
it is very subjective and tolerance varies between people
what is pain
an unpleasant sensory and emotional experience associated with actual tissue damage or described in terms of such damage
how does chronic pain prevalence change with age
more common in elderly
what is transduction
translation of noxious stimulus into electrical activity at the peripheral nociceptor (how body conveys stimulus to CNS)
what is transmission
propagation of pain signal as nerve impulses through the nervous system
what is modulation
modification/hindering of pain transmission in the nervous system by inhibitory neurotransmitters like endogenous opioids
what is perception
conscious experience of pain
where does pain begin
with the activation of nociceptors
what are nociceptors
specific primary sensory afferent neurons normally activated by intense noxious stimuli
what are the neurotransmitters in the nociceptive pathway
glutamate and peptides
are nociceptors first or second order neurons
first order
through what system do the second order neurons ascent the spinal cord
the anterolateral system terminating in the thalamus
what does the spinothalamic tract do
involved in pain perception
what does the spinoreticular tract do
involved in autonomic responses to pain, arousal, emotional responses, fear of pain
what relays the sensory information from the thalamus to the primary sensory contex
third order neurons
what are A gamma fibres
mechanical/thermal nociceptors that are thinly myelinated
respond to mechanical and thermal stimuli , mediate ‘first’ or fast pain
what are C fibres
nocioceptors that are unmyelinated and collectively respond to all noxious stimuli eg. polymodal and mediate ‘second’ or slow pain
examples of pain felt through A gamma fibres
lancinating
stabbing
pricking
pain sensations felt through C fibres
burning
throbbing
cramping
aching
what is nociceptive pain
pain that is a normal response to injury of tissue by damaging stimuli
only provoked by intense stimulation of nocioceptors
adaptive (changed with healing)
why do we have nociceptive pain
as an early warning physiological protective system to detect and avoid noxious stimuli
what is inflammatory pain
caused by activation of the immune system by tissue injury or infection
activated by mediators released at the site of inflammation
also causes heightened pain sensitivity to noxious stimuli (hyperalgesia)
adaptive pain (changes with healing)
why do you get heightens sensitivity to noxious pain when there is inflammation
to discourage physical contact with the affected part and movement
what is neuropathic pain
pathological pain
caused by damage to neural tissue
what are some examples of neuropathic pain
compression neuropathy peripheral neuropathy central pain (following stroke or spinal injury) post therautic neuralgia trigeminal neuralgia phantom limb
how is neuropathic pain perceived
as burning shooting numbness pins and needles may be less localised
what is dysfunctional pain
pathological pain
no identifiable damage or inflammation
simple analgesics not usually very effective
maladaptive pain (not protective)
examples of dysfunctional pain
fibromyalgia IBS tension headache temporomandibular joint disease intersititial cystitis
What is referred pain
pain developed in one part of the body felt in another structure away from the place of its development
what types of pain can be referred
deep or visceral pain
what causes referred pain
convergence of nociceptive visceral and skin afferents upon the same spinothalamic neurons at the same spinal level
(brain gets confused)
where can pain from the heart be referred to
the jaw
down the left arm
where can pain from the liver be referred to
the right shoulder
where can pain from the diaphragm and lungs be referred to
the left shoulder
where can pain from the stomach/appendix be referred to
epigastric region
where can pain from the gallbladder be referred to
right shoulder
