Term
Pain…
Is one modality of __________
Is the ________ of unpleasant or aversive stimulation (sensory and emotional experience)
Warns of _______ (physiological relevance) |
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Definition
Is one modality of somatosensation
Is the perception of unpleasant or aversive stimulation (sensory and emotional experience)
Warns of injury (physiological relevance) |
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Term
True or false
Pain is highly individual and subjective |
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Definition
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Term
| What pathways carries pain information? |
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Definition
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Term
| The spinothalamic tract is part of what ascending sensory system? |
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Definition
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Term
| Small DRG unmyelinated axons that enter the cord for pain and temperature are ____ fibers. |
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Definition
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Term
| small DRG unmyelinated axons (C fibers) enter the cord and synapse in _____________, the cross in the ___________ and ascend in the __________ tract. |
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Definition
| synapse in substantia gelatinosa (lamina II), then cross in the Ventral White Commissure and ascend in the Anterolateral Tract. |
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Term
| Under normal conditions, C fibers release what neurotransmitter to activate AMPA receptors? |
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Definition
| Glutamate (tiny vesicles) |
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Term
| If there is a high frequency of action potentials (high intracellular Ca+), what neurotransmitter will C fibers release? |
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Definition
| Substance P (denser vesicles) |
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Term
| Where do primary afferent C fibers synapse |
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Definition
| on dendrite within substantial gelatinosa (layer II) |
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Term
| What neurotransmitter enhances and prolongs the action of glutamate acting on AMPA receptors? |
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Definition
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Term
Are delta fibers myelinated?
Are they smaller or bigger than C fibers?
Do they transmit slower or faster than C fibers? |
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Definition
myelinated
bigger
transmit faster |
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Term
Which lamina do delta fibers synapse?
Which lamina do C fibers synapse |
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Definition
I (marginal layer of dorsal horn)
II (substantia gelantinosa of dorsal horn) |
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Term
What fibers are for proprioception?
Where do they synapse? |
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Definition
beta fibers
lamina V and ventral horn (important for reflexes) |
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Term
| What type of information is conducted the fastest? |
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Definition
| proprioception (evolutionary advantage of running away) |
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Term
| What fibers are the fastest- bigger and myelinated? |
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Definition
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Term
| What fibers are small but myelinated? |
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Definition
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Term
| What fibers are unmyelinated and small, slow. |
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Definition
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Term
What fibers are involved with sharp pain?
What fibers are involved with dull pain? |
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Definition
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Term
| What are the free nerve endings of primary sensory DRG and trigeminal ganglia neurons (a few wrap arounds of schwann cells, no connective tissue, just free branches) |
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Definition
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Term
| What activates nociceptors? |
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Definition
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Term
| Membran contains "____________" receptors |
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Definition
| sensory detection (non-selective cationic channels, Na+, Ca2+) |
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Term
| What receptor detects noxious heat (>53 degrees C)? |
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Definition
| TRPV2 (transient receptor potentials vanilloid 2) |
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Term
| What receptor detects capsaicin (chili)/ vanillin (~43 degrees C)? |
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Definition
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Term
| What receptor detects warmth (~27-39 degrees C)? |
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Definition
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Term
| What receptor detects menthol/icilin (cool ~20 degrees C)? |
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Definition
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Term
| What receptor detects noxious cold (<5 degrees C)/garlic/wasabi? |
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Definition
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Term
| What are the classes of nociceptors that are all located in skin and deep tissues? |
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Definition
Thermal - extreme temperatures – A-delta fibers
Mechanical - intense pressure – A-delta fibers - sharp pain
Polymodal - both intense mechanical, chemical or thermal stimuli – C fibers (unmyelinated) – dull burning |
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Term
True or false:
Pain sensation and pressure sensation have the same axons. |
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Definition
False
pain sensation is not the same as pressure sensation like the corpuscles. You can press harder, but it's more like touch, and it doesn't fire any faster based on pressure. It’s not encoding pain just because you press harder. Pain is mediated through a completely different set of axons |
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Term
| When cells are damaged (endothelial/platelets), it releases chemicals that activate and sensitize (hyperalgesia-cause increase pain) at the ___________. |
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Definition
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Term
After chemicals stimulate nerve endings during an injury, they are depolarized and fire AP to excite the __________ neuron in the dorsal horn.
These mediators released at the site of injury causes _______/________. |
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Definition
dorsal ganglion
vasodilation/extravasation (neurogenic inflammation) |
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Term
| How does aspirin work to reduce inflammation? |
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Definition
| inhibits arachidonic acid cyclooxygenase |
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Term
Thermal nociceptors are members of the ________ gene family.
Are they (selective or non-selective) cation channels? |
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Definition
transient receptor potential (TRP)
non-selective - Na, Ca |
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Term
True or false:
Thermal nociceptors are activated at all temperatures |
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Definition
False
Activated by extreme temp:
< 5 C or > 45 C |
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Term
True or false:
Thermal nociceptors are excitatory. |
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Definition
True
depolarizing (permeable to Na, K, and Ca) |
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Term
When pressing a blunt instrument on your finger, you will record __________ fibers.
When pressing a sharp instrument on your finger, you will record _________ fibers. |
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Definition
mechanosensory (pressure)
nerve ending (mechanical nociceptor) |
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Term
| Will pressing a sharp instrument on your finger report Pacinian and Ruffini corpuscles? |
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Definition
| No Pressure is NOT the same as pain |
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Term
| What is the term for when a stimulus that was not considered painful immediately after injury becomes perceived as painful (Repeated noxious leads to recruitment of previously unresponsive neighboring nociceptors)? |
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Definition
| hyperalgesia (sensitization) |
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Term
| What type of reflex is involved with sensitization of nociceptors? |
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Definition
| axon reflex (1 cell reflex) - no synapse between sensory arm and motor arm of the reflex |
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Term
| After tissue damage, the sensation to pain to subsequent stimuli is (increased or decreased) at primary and secondary (surrounding) sites of injury? |
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Definition
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Term
| What is the term called when pain thresholds decrease or magnitude of pain from suprathreshold stimuli increases? |
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Definition
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Term
| What is the painful response to otherwise innocuous mechanical stimulus (ex: sunburn) |
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Definition
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Term
| With severe persistent injury, ___ fibers fire repetitively or "wind up" resulting in increased ______ release in the spinal cord that activates _______ receptors. |
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Definition
| With severe persistent injury, C fibers fire repetitively or “wind up” resulting in increased glutamate release in spinal cord that activates NMDA receptors (permeates calcium) |
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Term
When the C fibers fire repetitively resulting increased glutamate release, which activates NMDA receptors, what happens that causes up regulation of transmitters and receptors?
What type of sensitization is this? |
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Definition
synaptic plasticity
central sensitization (ex: phantom limb pain) |
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Term
| What tract does the pain sensation follow? |
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Definition
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Term
Is the spinothalamic tract, in the white or gray matter in the spinal cord?
Where does it go in the thalamus?
Where does it go in the cortex? |
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Definition
Antero-lateral white mater
central-lateral nucleus and ventral-posterior-lateral nucleus
postcentral gyrus (pain goes to same places as mechanosensory homunculus) |
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Term
Identify whether it is VPL/VPM (neospinothalamic) or Intralaminar complex (paleospinalthalamic) pain pathway through thalamus:
-receive nociceptive specific and other sensory inputs
-spinothalamic tract (STT & TTT)
-Includes projections from the spinoreticulothalamic tract
-project to primary somatosensory cortex
-diffuse cortical projections
-neurons have small receptive fields - injury location |
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Definition
-receive nociceptive specific and other sensory inputs (neospinothalamic)
-spinothalamic tract (STT & TTT) (neospinothalamic)
-Includes projections from the spinoreticulothalamic tract (paleospinalthalamic)
-project to primary somatosensory cortex (neo)
-diffuse cortical projections (paleo)
-neurons have small receptive fields - injury location (neo) |
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Term
What ascending pathway is responsible for arousal when there is pain?
Where does this tract go? |
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Definition
spinoreticular tract
to reticular formation of pons / medulla (level of attention); and onto thalamus |
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Term
What ascending pathway is responsible for emotion and memory integration of pain?
Where does this tract go? |
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Definition
Spinomesencephalic tract
to mesencephalic reticulum, lateral periqaueductal grey in midbrain; and on to hypothalamus and limbic system (emotion and memory integration) |
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Term
Where does the spinoreticular tract receive collaterals?
Where does it synapse? |
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Definition
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Term
Where does the spinomesencephalic tract synapse?
Is it in ascending or descending control? |
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Definition
(periaqueductal gray matter) in the mid brain
descending control |
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Term
| (ascending or descending) pathways can regulate relay of nociceptive information in the spinal cord. |
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Definition
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Term
If you stimulate the ________ area of the brain, you can modulate the sensation of pain.
However, what are the other parts that you can stimulate noradrenaling and serotonin to slow the integration of AP from the primary afferent to synapse in the dorsal horn? |
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Definition
PAG (periaqueductal gray mater)
locus ceruleus and nucleus raphe |
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Term
| How does morphine work as an analgesic? |
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Definition
| activates receptors on locus ceruleus to control the level of excitation where information comes in (doesn't make you numb like sodium channel blocker in primary afferent that prevents transmission of the AP) |
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Term
| Where are the 2 places where external and endogenous opioids work? |
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Definition
pre-synaptic sensory neuron (smaller AP)
post-synaptic sensory neuron (smaller EPSP) |
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Term
Determine if the opioid is working on the presynaptic or postsynaptic neuron:
Opening K+ channel hyper polarizes terminal so action potential is smaller (thus less glutamate and substance P --> less pain formation coming into dorsal horn) |
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Definition
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Term
Determine if the opioid is working on the presynaptic or postsynaptic neuron:
Opening K+ channel hyperpolarizes cell and causes inhibitory conductance and shunting which makes the EPSP smaller. |
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Definition
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Term
True or False:
You can make yourself feel or not feel pain. |
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Definition
True
Placebo effect- your own convictions can trigger areas in the brain (raphe, locus coeruleus, PAG) to release endogenous opioids, endorphins, and modulate pain |
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Term
| What fibers can stimulate the local inhibition C fiber cause a reduced or weak activation of the postsynaptic neuron sending up the sensory pathway? |
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Definition
| beta fibers (proprioception)/intrafusal fibers - why we rub skin or shake when something is painful |
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Term
| VPL / VPM project to ______________ cortex and then to secondary somatosensory cortex for awareness, location and “intensity” of pain |
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Definition
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Term
| Medial thalamus projects to anterior ______ cortex for autonomic / visceral component of pain |
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Definition
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Term
| Intralaminar nuclei of medial thalamus projects to ______ _______ cortex (limbic association cortex) for emotional component of pain (circuit of Papez) |
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Definition
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Term
| What type of pain is it when visceral pain maps out in nearby regions of the skin? |
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Definition
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Term
| What nociceptors are normal not active but firing threshold reduced by various insults. |
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Definition
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Term
| What is released by nociceptors which causes mast cells to release histamine, which in turn stimulates the nociceptors? |
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Definition
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Term
| In referred pain, there is a convergence of somatic and visceral afferents on lamina ___. |
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Definition
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Term
Which is the one we haven’t talked about related to pain?
1. dorsal horn
2. STT
3. PAG
4. Raphe
5. Locus coeruleus
6. Substantia nigra |
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Definition
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