PAIN Flashcards
Define sensation
It is what is picked up by our receptors and transfered back to our CNS
Define perception
What the brain sees those signals as (seeing the box within the circles)
Name modalities
Pressure, touch, stretch, acceleration, sound waves, light, chemical, temperature
Law of specific nerve energies
a given sensory receptor is specific for each modality
Direct vs indirect stimulus
Direct has the stimulus acting on the body or the dendrites.
Indirect has the stimulus acting on a separate cell that signals the primary afferent
Nociceptor thresholds
Strong pressure (needle)
High or low heat (>45, <20)
Bradykinin, histamine, acids, irritants
Nociceptor types
nonselective cation channels (TRP)
acid sensing ion channels (ASIC)
indirect (P2X, P2Y AND TKA)
Piezo channels
pressure activated via mechanical opening
TRPV1
nociceptor activated by heat, acids (capsaicin)
TRPV3 and 4
Average level temperature sensors
TRPA1
nociceptor activated by mechanical, cold, chemical
TRPM8
nociceptor activated by menthol (cool)
ASIC
nociceptors activated by pH changes
P2X and P2Y
indirect receptors that activate primary afferent nociceptor neurons. `
Free nerve endings
Fiber type: A delta or C
Location: superficial skin
Receptive field: small
Adaptation speed: slow
Modality: light touch
Merkels disk
Fiber type: A beta
Location: superficial skin
Receptive field: small
Adaptation speed: slow
Modality: pressure
Pacinian corpuscle
Fiber type: A beta
Location: deep skin
Receptive field: large
Adaptation speed: fast
Modality: vibration
meissners corpuscle
Fiber type: A beta
Location: superficial glabrous
Receptive field: small
Adaptation speed: fast
Modality: vibration
hair follicle
Fiber type: A beta
Location: superficial skin (hairy)
Receptive field: small
Adaptation speed: fast
Modality: bending hair
ruffinis endings
Fiber type: A beta
Location: deep, hairy skin
Receptive field: large
Adaptation speed: slow
Modality: pressure
warm receptors
Fiber type: C
Location: superficial skin
Receptive field: small
Adaptation speed: fast
Modality: increased temp
cold receptors
Fiber type: A gamma
Location: superficial skin
Receptive field: small
Adaptation speed: fast
Modality: decrease in temp
mechanical nociceptor
Fiber type: A delta
Location: superficial skin
Receptive field: large
Adaptation speed: slow
Modality: intense pressure
thermal nociceptor
Fiber type: A delta
Location: superficial skin
Receptive field: small
Adaptation speed: fast
Modality: intense hot or cold
Polymodal nociceptors
Fiber type: C
Location: superficial skin
Receptive field: large
Adaptation speed: slow
Modality: many stimuli as they are polymodal
Second pain activation
stimulated by glutamate and substance P release from C fibre activation
hyperalgesia
when something hurts it hurts much more than it should
Allodynia
what shouldn’t hurt now does
paracrine pain mediators
Bradykinin
prostaglandins
substance P
CGRP (calcitonin gene-related peptide)
histamine
5-HT (serotonin?)
nociception and temperature pathway
Ventrolateral spinothalamic pathway
-cross over in the spinal cord
Convergence projection theory
Leads to referred pain from skin and visceral afferents synapsing in a similar location
Neuropathic pain
burning sensation that occurs on it’s own by a light touch
Central sensitization
increase of excitability and spontaneous discharge of the dorsal horn neurons with an associated increase in the receptive field of these neurons.
-causes hyperalgesia
Central sensitization receptors
Primarily Glu receptor up regulation and thus increase of Ca2+ in the cell cause CS
-AMPA (Na channel)
-Kainate (Na channel)
-NMDA (Ca2+ channel)
