EX1; Peripheral Pain Flashcards Preview

AU14 Physiology > EX1; Peripheral Pain > Flashcards

Flashcards in EX1; Peripheral Pain Deck (67):
1

This type of pain is short term with an identifiable source

acute pain

2

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

chronic pain

3

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

13%; A-delta
87%; C fibers

4

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

tiny/unmyelinated = C
small/myelinated = Adelta

5

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

Adelta is faster than C

6

Which fiber has neuropeptides (but limited)

Adelta

7

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

C fibers
A delta is just mainly TTX-sensitive (typical)

8

What are the response properties of A delta fibers

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

9

What are the response properties of C fibers

varied stimuli buy many POLYMODAL (but all noxious)

10

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

A delta; TRPV-1 expression is rare, TRPV-2 more likely
C fibers; many express TRPV-1

11

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

A delta

12

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

C fibers

13

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

ENaCS (epithelial sodium channels)

14

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

transient receptor potential (TRP)

15

TRP receptors are also involved with the is type of transduction

non-noxious thermal transduction

16

TRP receptors found here respond to chemicals to mediate chemesthesis

trigeminal sensory fibers

17

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

odontoblasts

18

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

polymodal

19

Specialized ending and chemesthesis allow for an important distinction between what

taste and olfaction

20

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

spicy food; capsaicin
burning and tingling

21

This term means no olfactory sensation

anosmic

22

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

capsaicin

23

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

capsaicin
heat (42°C)
protons

24

stimulations of vanillin receptors results in what

the influx of cations (Na and Ca)

25

What are the branches of the trigeminal nerve with prominent chemesthesis

nasal; ethmoid (smelling salts)
oral; posterior palatine, nasopalatine, lingual nerve

26

Is chemesthesis high or low threshold chemosensitivity

high

27

What is the predominate type of sensation of chemesthesis

aversive; burning, tingling

28

Chemesthesis also plays a role in "removal" reflexes such as what

salivation
coughing
tearing
sneezing

29

Chemesthesis can also be activated by two other things

dental compounds
drugs (capsaicin compounds) for pain treatment

30

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

a-delta fibers

31

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

calcitonin gene-related peptide (CGRP)

32

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

c fibers

33

What kind of sensitivity do c-fibers respond to

thermal sensitivity
chemosensitivity to inflammatory mediators (bradykinin)

34

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

hydrodynamic theory

35

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

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

36

What evidence supports the hydrodynamic theory of pain

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

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

smear layer

38

What are the three major characteristics of hyperalgesia

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

Interactions between what things can induce hyperalgesia

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

40

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

thermal or mechanical injury

41

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

vasodilation
plasma extravasation (swelling)

42

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

bleeding

43

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

infection

44

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

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

This is something that directly stimulates nociceptor cells

algesics; like bradykinin

46

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

hyperalgesia

47

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

TTX-insensitive sodium channels

48

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

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

49

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

prostaglandins

50

This is a burning pain associated with nerve damage

causalgia

51

This is light touch leading to pain associated with nerve damage

allodynia

52

This is temperature induced pain associated with nerve damage

sympathetic nerve dystrophy

53

This is sensation in denerved tissue associated with nerve damage

phantom sensations

54

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

retrogrades chages

55

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

chromatolysis

56

Chromatolysis is a historical marker for what

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

57

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

True

58

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

transganglionic degeneration

59

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

transneuronal degeneration

60

What are two anterograde changes associated with nerve injury

terminal degeneration of axon terminal
wallarian anterograde degeneration of axon

61

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

Schwann cells

62

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

sprouting

63

Can sprouting have functional significance?

yes, has been indicated in a human subject

64

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

neuromas

65

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

ectopic discharge

66

What two phenomena can cause pain in an neuroma

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

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

ephaptic