MODULE 5- Pain + Temperature Flashcards

1
Q

nociceptors

A

unspecialized, nonspecific nerve endings that transmit a variety of stimuli + translate then into afferent APs

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2
Q

2 kinds of slowly transmitting afferent fibers

A

-Aδ (delta) lightly myelinated axons
-C unmyelinated axons, small diameter

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3
Q

pain is transmitted only when strength of stimulus is low/high

A

high

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4
Q

2 categories of pain

A

-faster conducting sharp FIRST PAIN carried by Aδ fibers
-delayed, broadly acting, dull SECOND PAIN carried by C fibers, which respond to all types of nociceptive stimuli

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5
Q

faster conducting sharp FIRST PAIN is carried by Aδ/C fibers

A

Aδ fibers

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6
Q

`

delayed, broadly acting, dull SECOND PAIN is carried by Aδ/C fibers

A

C fibers

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7
Q

2 types of Aδ fibers

A

-type 1
-type 2

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8
Q

type 1 Aδ fibers

A

-high heat thresholds
-respond to immediate potentially dangerous stimuli (e.g., pin prick)

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9
Q

type 2 Aδ fibers

A

-low heat threshold
-high threshold for mechanical stimulation

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10
Q

what does capsaicin activate

A

TRPV1 (VR-1)
-whose endogenous ligand is anandamide + temperature

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11
Q

where is capsaicin found

A

chili peppers, habanero, etc.

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12
Q

when is capsaicin an irritant

A

when applied to mucus membranes of the mouth + when injected subcutaneously

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13
Q

repeated administration of capsaicin leads to

A

desensitization

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14
Q

how is capsaicin clinically useful

A

as an analgesic + anti-inflammatory agent

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15
Q

central pain pathways (3)

A

-dorsolateral tract of Lissauer
-anterolateral system (AL)
-dorsal-column medial lemniscal system (DCML)

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16
Q

dorsolateral tract of Lissauer

A

ascending + descending branches of incoming afferent axons entering the dorsal horn

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17
Q

anterolateral system (AL)

A

formed from 2nd-order neuronal axons in the dorsal horn laminae I + V (wide dynamic range neurons)
-ascends carrying pain, temperature, + crude touch information to somatosensory cortex via the thalamus

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18
Q

dorsal-column medial lemniscal system (DCML)

A

carries mechanical stimuli
-touch, pressure, vibration, proprioception

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19
Q

AL + DCML systems are separate or together in the spinal cord

A

separate

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20
Q

where does the AL system decussate

A

at the point of entry into the spinal cord

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21
Q

where does the DCML system decussate

A

at the medulla

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22
Q

pain + temperature are ipsilateral/contralateral

A

contralateral

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23
Q

touch + pressure are ipsilateral/contralateral

A

ipsilateral

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24
Q

dermatomes

A

enable diagnosis of the location of the spinal cord injury

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25
Q

how is visceral (internal) pain transmitted

A

via dorsal horn neurons that also convey cutaneous pain

26
Q

2 common examples of referred pain

A

-anginal pain arising because of inadequate blood flow in the heart is referred to the left arm + hand
-gall bladder pain referred to the scapular region

27
Q

anginal pain arising because of inadequate blood flow in the heart is referred to

A

left arm + hand

28
Q

gall bladder pain is referred to

A

scapular region

29
Q

different aspects of pain are transmitted by ____ pain pathways

A

parallel

30
Q

anterolateral system- sensory discriminitive

A

mediates location, intensity, quality of the noxious stimulus

31
Q

sensory discriminitive information is conveyed from ____ to ____

A

anterior spinothalamic tract ->
ventral posterior lateral nucleus of thalamus

32
Q

anterolateral system- affective motivational

A

unpleasant feelings, fear + anxiety
-autonomic reactions that accompany noxious responses, such as the sympathetic nervous system

33
Q

pain matrix

A

extensive network of forebrain regions enabling one to experience the full range of pain

34
Q

what does the pain matrix consist of

A

ventral posterior medial thalamus, somatosensory, insular, + anterior cingulate cortices

35
Q

where does face pain originate

A

trigeminal (V) ganglion
-also from other ganglion associated with cranial nerves VII, IX, and X

36
Q

peripheral mechanisms of sensitization

A

-CGRP
-NSAIDs

37
Q

face pain climbs from ____ to ____

A

trigeminothalamic tract ->
ventral posterior medial thalamus

38
Q

hyperalgesia

A

perception that pain is worse than it would normally be considered to be

39
Q

peripheral sensitization

A

activated nociceptors stimulate the influx of non-neuronal cells (immune cells), neuropeptides + neurotransmitters, lipids, cytokines, + growth factors, all of which contribute to INFLAMMATION

40
Q

purposes of sensitization (hyperalgesia, peripheral sensitization)

A

protect the injured area, promote healing, + ward off infection

41
Q

pain is subjective/objective

A

subjective

42
Q

hyperalgesia example

A

if you take a hot shower with a sunburn

43
Q

how can hyperalgesia be initiated + maintained

A

by calcitonin gene-related peptide (CGRP)

44
Q

what can be used to treat pain sensitivity

A

nonsteroid anti-inflammatory drugs (NSAIDs)

45
Q

pathway for NSAIDs

A

inhibits cyclooxygenase ->
inhibits prostaglandin synthesis ->
reductoin in inflammation + pain

46
Q

central mechanisms + treatments for sensitization

A

allodynia

47
Q

allodynia

A

induction of pain by a normally innocuous stimulus
-caused by inadvertent stimulation of 2nd –order neurons in the dorsal horn that normally receive nociceptive inputs to give rise to a sensation of pain

48
Q

phantom limbs + phantom pain

A

illusion that the missing limb is still present
-amputation -> functional reorganization of the somatotopic map in the primary somatosensory cortex
-usually feels like a burning/tingling sensation where the limb used to be

49
Q

phantom limbs + pain are a common cause of

A

chronic pain syndrome

50
Q

phantom limbs + phantom pain may be caused by

A

maladaptive plasticity in neural circuits representing sensations + actions of the body

51
Q

reorganization of somatosensory cortex can cause

A

mapped cortical body parts to innervate contiguous (or adjacent) cortical areas, leading to misplaced feelings in the missing limb

-ex: stimulation of the left side of the face could lead to sensation that the left arm is being stimulated

52
Q

ramachandran’s mirror box therapy

A

visual reality presents a contradiction to what the patient feels in the missing limb
-while viewing the intact limb + its relection/ movements, the patient superimposes the missing limb into the mirror-reversed intact limb

53
Q

the placebo effect

A

a beneficial effect as a result of a pharmacologically inert “remedy”

54
Q

placebo effect in postoperative patients can be blocked by ____

A

naloxone

55
Q

imaging studies reveals that the placebo effect leads to

A

activation of opioid receptors in cortical + subcortical brain areas
-(e.g., anterior cingulate and insular cortices and amygdala)

56
Q

example of placebo effect

A

saline injection gives people relief even though it is just saline

57
Q

physiological basis of pain modulation- neurotransmitters used

A

wide variety of neurotransmitters used
-e.g., serotonin, dopamine, norepinpehrine

58
Q

physiological basis of pain modulation- mediates the analgesic effects of what

A

periaquaductal gray (PAG)

59
Q

physiological basis of pain modulation- what do descending projections to the dorsal horn do

A

balances excitatory and inhibitory interneurons
-plus the synaptic terminals of other descending pathways, to determine the efficiency of nociceptive transmission

60
Q

physiological basis of pain modulation- interactions between what 2 things modulate the transmission of nociceptive information to higher centers

A

mechanoreceptor afferents + dorsal neural circuits

61
Q

Melzack + Wall’s gate control theory of pain

A

concomitant activation of low-threshold mechanoreceptors can mitigate ascending nociceptive signals

ex: rubbing your finger that you accidentally hit with a hammer -> pain transmission