Exam Two - neurobiology of pain Flashcards
nociception
the physiological process underlying the sensation of pain
- allows the body to naturally withdraw from the noxious stimulus and trigger the body to secrete analgesics
pain
an unpleasant sensory and emotional experience that is associated with actual or potential tissue damage
subjective awareness of tissue injury
pain
occurs in the brain and requires consciousness
pain
is an issue of psychological well being
pain
unconscious detection of tissue injury and transmission of injury signals to the brain
nociception
does not require consciousness
nociception
is an issue of physiological well being
nociception
acute pain
nociceptive, “normal”
useful as an acute warning system
chronic pain
pathological pain
debilitating and without biological value
pain is NOT generated by a hardwired system, but results from the activity of highly ________ molecules and circuits
plastic
acute pain list
- comes on suddenly
- caused by something specifc
- sharp
- doesn’t last more than a few weeks
- can be treated with OTC meds
- causes like burns, cuts, childbirth
- survival mechanism, protective
chronic pain list
- more than 3 months
- no biologic value
- persists past normal tissue healing
alterations of the pain pathway causes ___________, such that acute pain outlives its usefulness as a warning system and instead becomes chronic and debilitating
hypersensitivity
short term sensitization
starts as part of the normal healing process: tissue or nerve damage cause hyperactivity of nociceptors to promote “guarding” of the area
long term sensitization
short term sensitization fails to resolve
mechanisms of long term sensitization
- increased excitability of nociceptors
- changes in gene expression
- activation of second messenger cascades
(they all rewire the nervous system)
hyperalgesia
heightened sense of pain to noxious stimuli
allodynia
pain resulting from normally not painful stimuli
the 4 processes of the pain pathway
1 - transduction
2 - transmission
3 - perception
4 - modulation
____________ is the net result of excitatory and inhibitory neuronal activity
pain sensation
nociceptors are ________ of the primary afferent nerve fiber
free nerve endings
mechanical receptors
high threshold mechanoreceptors
thermal receptors
temp greater than 45C or less than 5C
polymodal nociceptors
respond to mechanical, thermal, and chemical energy that causes tissue damage
nociceptors _____ noxious sensory info into the language of the nervous system: electrical current
transduce (convert)
A-delta fibers
- high threshold of sensitivity
- free nerve endings are mechanoreceptors and thermoreceptors
- myelinated fibers
- 5-30 m/sex
- transmit first/transient pain information
- localized, sharp, stinging, pricking
- tolerance is uniform from person to person
first pain is carried by…
A-delta fibers
C fibers
- low threshold of sensitivity
- free nerve endings are polymodal
- unmyelinated fibers
- slow transmission
- transmit second and persistent pain info (chronic pain)
- diffuse, burning, aching
- tolerance varies from person to person
second pain is…
poorly localized slow pain
chemical mediators of pain are called…
inflammatory soup
composition of inflammatory soup
- tissue mediators released by damaged tissue and immune cells
- INFLAMMATORY PAIN
- Neurotransmitters
