EX1; Peripheral Pain Flashcards

1
Q

This type of pain is short term with an identifiable source

A

acute pain

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2
Q

This type of pain is long term frequently with a non-identifiable source

A

chronic pain

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3
Q

This type of fiber makes up roughly 13% of cutaneous nociceptors, while this fiber makes up roughly 87%

A

13%; A-delta

87%; C fibers

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4
Q

Which fiber is tiny (0.2-1.5µm) and is unmyelinated and which one is small (1-5µm) and is lightly myelinated

A
tiny/unmyelinated = C
small/myelinated = Adelta
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5
Q

Which fiber has a faster conduction velocity (12-36m/s) compared to 0.5-1.2m/s

A

Adelta is faster than C

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6
Q

Which fiber has neuropeptides (but limited)

A

Adelta

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7
Q

Which fiber has its Na channels both TTX-sensitive (typical) and TTX-r (sensory-nerve specific)

A

C fibers

A delta is just mainly TTX-sensitive (typical)

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8
Q

What are the response properties of A delta fibers

A

noxious mechanical stimuli
some noxious heat
chemical stimuli; inflammatory mediators but not capsaicin

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9
Q

What are the response properties of C fibers

A

varied stimuli buy many POLYMODAL (but all noxious)

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10
Q

What is the TRPV-1/2 expression for Adelta and C fibers

A

A delta; TRPV-1 expression is rare, TRPV-2 more likely

C fibers; many express TRPV-1

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11
Q

This fiber is the first pain, fast, sharp, and well localized

A

A delta

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12
Q

This fiber is 2nd pain, slow, dull or burning, poorly localized pain

A

C fibers

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13
Q

These channels may play a role in mechanical nociception; very speculative

A

ENaCS (epithelial sodium channels)

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14
Q

This is a large family of receptors transducing chemical and thermal nocicpetion (possibly mechanoreception)

A

transient receptor potential (TRP)

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15
Q

TRP receptors are also involved with the is type of transduction

A

non-noxious thermal transduction

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16
Q

TRP receptors found here respond to chemicals to mediate chemesthesis

A

trigeminal sensory fibers

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17
Q

TRP receptors are also found here; with a possible role in tooth pain

A

odontoblasts

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18
Q

C-fibers innervating the oral and nasal mucosa have a small receptive field and what kind of chemorecpetive properties

A

polymodal

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19
Q

Specialized ending and chemesthesis allow for an important distinction between what

A

taste and olfaction

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20
Q

The response of trigeminal C-fibers that signals pain and sensations associated with what

A

spicy food; capsaicin

burning and tingling

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21
Q

This term means no olfactory sensation

A

anosmic

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22
Q

A large proportion of polymodal c-fibers and a few a-deltas are sensitive to what

A

capsaicin

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23
Q

Vanilloid receptor (TRPV1 or V1) responds to what three things

A

capsaicin
heat (42°C)
protons

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24
Q

stimulations of vanillin receptors results in what

A

the influx of cations (Na and Ca)

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25
Q

What are the branches of the trigeminal nerve with prominent chemesthesis

A

nasal; ethmoid (smelling salts)

oral; posterior palatine, nasopalatine, lingual nerve

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26
Q

Is chemesthesis high or low threshold chemosensitivity

A

high

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27
Q

What is the predominate type of sensation of chemesthesis

A

aversive; burning, tingling

28
Q

Chemesthesis also plays a role in “removal” reflexes such as what

A

salivation
coughing
tearing
sneezing

29
Q

Chemesthesis can also be activated by two other things

A

dental compounds

drugs (capsaicin compounds) for pain treatment

30
Q

These fibers are found 0.1-0.2mm into dentinal tubules and are associated with sharp pain

A

a-delta fibers

31
Q

The a-delta fibers of dentinal tubules contain what, associated with mechanical and thermal sensitivity, also chemical stimuli like NaCl.

A

calcitonin gene-related peptide (CGRP)

32
Q

These fibers are found in the tooth pulp and contain substance P; initiating a dull, throbbing pain

A

c fibers

33
Q

What kind of sensitivity do c-fibers respond to

A

thermal sensitivity

chemosensitivity to inflammatory mediators (bradykinin)

34
Q

This theory holds that despite the lack of innervation of the DEJ, this area is sensitive to mechanical, thermal, and chemical stimuli causing fluid to flow in the tubules

A

hydrodynamic theory

35
Q

Fluid flow of the hydrodynamic theory causes what to occur, stimulating a response

A

the fluid flow causes distortion in proximal parts of dentinal tubules where the sensory endings are located, thus stimulating the receptor

36
Q

What evidence supports the hydrodynamic theory of pain

A

noxious temperature was applies to dentin and subjects reports of pain were directly correlated between the integrated nerve activity (INA) and increased pain response (PAS), since the pain was described as “sharp” this indicates that they are a-delta fibers of which are found in the tubules

37
Q

This is extremely important in the transduction process involving the hydrodynamic theory, when this was removed, subjects experienced pain

A

smear layer

38
Q

What are the three major characteristics of hyperalgesia

A
  1. greater responsiveness to stimuli (both nociceptive and low-threshold)
  2. pain is spontaneous in occurrence (lack of obvious stimulus)
  3. pain is prolonged
39
Q

Interactions between what things can induce hyperalgesia

A

interactions between different neural systems (afferent/efferent(
interactions between nervous and non-nervous cells

40
Q

This stimulates nociceptors to secrete substance P which in turn releases histamine, in turn, re-stimulates nociceptor

A

thermal or mechanical injury

41
Q

Histamine also promotes these two things which can further act as a mechanical stimulus on nociceptors

A
vasodilation
plasma extravasation (swelling)
42
Q

This results in the release of bradykinin which stimulates nociceptors and further result in stimulation of histamine release from mast cells

A

bleeding

43
Q

This results in leukocyte products such as prostaglandins sensitize cells rather than directly stimulate them to produce action potentials

A

infection

44
Q

Many of cells involved in an inflammatory reaction release factors that are either these three things

A

algesics
stimulate other cells to release factors that are algesics (subP stimulates mast cells to release histamine)
do not directly stimulate nociceptor neurons but are involved in the process of sensitization

45
Q

This is something that directly stimulates nociceptor cells

A

algesics; like bradykinin

46
Q

The vanilloid receptor undergoes this, by becoming more sensitive to heat and capsaicin after protons are released in an inflamed area; more sensitive (22 degrees instead of 44) to other stimuli now

A

hyperalgesia

47
Q

C-fibers contain this, which unlink A fibers, require greater depolarization thus leading to a higher threshold

A

TTX-insensitive sodium channels

48
Q

C-fibers have small conductance K channels that function to do what

A

prolong the period of hyperpolarizaion following an action potential; thus producing fewer action potentials per unit of depolarization compared to A fibers

49
Q

The K channels in C fibers can be blocked by what, thus returning the membrane potential of transmitting painful signals; “sensitized”

A

prostaglandins

50
Q

This is a burning pain associated with nerve damage

A

causalgia

51
Q

This is light touch leading to pain associated with nerve damage

A

allodynia

52
Q

This is temperature induced pain associated with nerve damage

A

sympathetic nerve dystrophy

53
Q

This is sensation in denerved tissue associated with nerve damage

A

phantom sensations

54
Q

This type of change is toward the cell body; such as ganglion cell death if the axon is cut near the cell body

A

retrogrades chages

55
Q

If cell death does not occur, the cell body can undergo this, which the cell swells and the nucleus moves to an eccentric position and the RER moves to the side

A

chromatolysis

56
Q

Chromatolysis is a historical marker for what

A

damages or injured cell and is associated with increases protein synthesis in response to repair or injury

57
Q

True or False
Increased protein synthesis of a damaged nerve can lead to changes in cell properties like if more channel proteins are made, then that cell may become more sensitive to new things also due to lack of myelin

A

True

58
Q

Damage to the axon can result in this, in which the axon process heading towards the CNS degenerates

A

transganglionic degeneration

59
Q

This can occur in which the neuron contacted centrally by the axon dies

A

transneuronal degeneration

60
Q

What are two anterograde changes associated with nerve injury

A

terminal degeneration of axon terminal

wallarian anterograde degeneration of axon

61
Q

These in the vicinity of the lesion proliferate and produce ECM that provides substrate for regenerating axon

A

Schwann cells

62
Q

This phenomenon is most likely to occur when an axon fails to regenerate; a surviving axon may grow new terminals into the area previously occupied by the other sensory cell

A

sprouting

63
Q

Can sprouting have functional significance?

A

yes, has been indicated in a human subject

64
Q

These can form which reflect the regenerative capacity of injured nerves; it is anatomically characterized as a tangled complex, disorganized web of neural tissue, leading in some instances to painful conditions when palpated or arising spontaneously

A

neuromas

65
Q

An up regulation of Na channels makes for increased excitability and this, which is when a neuron responds, not from its receptor ending, but from stimulation of the cell body or axon

A

ectopic discharge

66
Q

What two phenomena can cause pain in an neuroma

A

sprouting; fibers with central connections that signal pain (nociceptor stimulation)
ephaptic; (non-synaptic) connections between neurons in neuroma such that low threshold mechanoreceptors now activate pain fibers

67
Q

This is when a neuron responds to action potentials from nearby neuron; could account for allodynia and referred pain

A

ephaptic