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Flashcards in travers- peripheral pain Deck (51)
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1
Q

what are the dimensions of pain?

A

1) Acute vs. Chronic
2) Sensation of pain vs affective component
3) “Normal” vs Pathological Pain

2
Q

what is the difference between pain sensation and the affective component?

A

sensation= Localization and intensity

affective component= Emotional response (psychological component)

3
Q

how is “normal” pain mediated? how is pathological pain mediated?

A

“normal” pain- A-delta and c-fiber mediated

pathological pain- Peripheral & central sensitization

4
Q

basic characteristics of A-delta fibers:

A

makes up 13% of cutaneous nociceptors

Small & lightly myelinated

responds to noxious mechanical stimuli

its the “1st pain- sharp and localized”

5
Q

basic characteristics of C fibers

A

makes up 87% of cutaneous nociceptors

tiny & unmyelinated

responds to varied stimuli, many POLYMODAL (but all noxious)

its the “2nd pain- slow, dull or burning, poorly localized”

6
Q

Both ______ channels and _____ receptors play a role in Pain transduction

A

ENaCS :(epithelial sodium channels)

TRP (transient receptor potential) receptors

7
Q

T/F: Some “Pain”/nociceptor TRP channels also have Chemosensitivity

A

true

8
Q

Chemesthesis is the response of _______ to chemical stimuli

A

c-fibers

9
Q

what sensations are associated with chemesthesis

A

Burning & tingling

e.g.
salt water on an open wound
Chili peppers in food (capsaicin)

10
Q

what does the Vanilloid Receptor (TRPV1 or V1) respond to? what does it trigger?

A

Responds to:

1. capsaicin
2. heat (42 degrees C)
3. protons

stimulation results in influx of cations (Na+ and Ca2+)

11
Q

which branches of the Trigeminal nerve contains prominent chemesthesis sensation?

A

Nasal branch:
1) ethmoid

Oral branch:

1) Posterior palatine
2) Nasopalatine nerve
3) LINGUAL NERVE

12
Q

Chemesthesis is Mediated by ______ receptors

A

TRP

13
Q

Chemesthesis predominately transmits ______ sensations

A

aversive

e.g. burning, tingling
probably not “banana” or “salty”

14
Q

dentinal tubules are occupied by which type of nerve fibers? What type of sensation are they responsible for?

A

A-delta fibers

  • contain calcitonin gene related peptide (CGRP)
  • mechanical & thermal sensitivity
  • sharp pain
15
Q

the pulp chamber is filled with which type of nerve fiber? what sensation is it responsible for?

A

C fibers

contain Substance P (SP)
thermal sensitivity
chemosensitivity to inflammatory mediators
dull throbbing pain

16
Q

within the tooth, _______ fibers respond to algesic stimuli such as bradykinins

A

C fibers

-has a long latency

17
Q

which dentinal fibers respond to temperature?

A

Dentinal A-fibers AND C-fibers can Respond to Temperature

The sensation from this stimulation is sharp pain in the dentin tubules, throbbing pain in the C-fibers

18
Q

high pressure applied to dentinal tubules does not cause pain, unless what happens?

A

EDTA dissolves smear layer

THEN pressure causes pain

19
Q

T/F: there is communication between odontoblasts

and nerve terminals

A

False

Communication has not been demonstrated

20
Q

what is the physiological evidence that supports the hydrodynamic theory?

A

A-delta fibers respond to mechanical, thermal,osmotic stimuli

Odontoblast may act as mechanoreceptor cell

21
Q

what are the characteristics of Hyperalgesia?

A
  • greater responsiveness to stimuli
  • pain is spontaneous
  • pain is prolonged
22
Q

what is allodynia?

A

response to non-painful stimuli produce pain

23
Q

___________ Mediators Affect Nociceptive Neurons

A

Inflammatory Mediators

24
Q

which inflammatory mediators directly stimulate nocioceptors?

A

histamine
bradykinin
5-HT

25
Q

which inflammatory mediators stimulate other cells to release algesics?

A

substance P: (from the nociceptor itself) stimulates histamine release

bradykinin: increases histamine release (mast cells)

26
Q

_________ are inflammatory mediators involved in sensitization

A

prostaglandins

27
Q

how does inflammation increase the sensitivity of the Vanilloid Receptor (TRPV1 or V1)

A
  1. Ca++ activated
    phosphorylation of VR1 receptor (TRPV1)
  2. Increase in receptor number
  3. Presence of inflammatory mediators (e.g.bradykinin & protons)
28
Q

Sensitization of TRPV1 lowers the ___________ threshold

A

temperature

29
Q

Sensitization by prostaglandins lowers the ___________ threshold

A

mechanical

30
Q

Pain Pathophysiology associated with Nerve Damage:

A

1) Causalgia
2) Allodynia
3) Sympathetic nerve dystrophy - temperature induced pain
4) Phantom sensations - sensation in denervated tissue

31
Q

Neuromas are caused by what?

A

collateral sprouting of nerve branches

can be painful

32
Q

what are the characteristics of C-fiber ectopic discharge?

A

A) Spontaneous activity

B) Prolonged responses to known stimulus

C) Initiation of response from atypical site

**Results from injury-induced increase in Na+ channels

33
Q

Ephaptic Transmission is a mechanism for which 2 conditions?

A

mechanism for allodynia and referred pain

34
Q

what are the mechanisms for peripheral sensitization?

A
  • Decreased threshold
  • Pain is spontaneous & prolonged
  • Ectopic discharge – (abnormal activation)
35
Q

what is the mechanism for ectopic discharge?

A

more Na+ channels following nerve injury

response to catecholamines following nerve injury

Ephaptic response due to increased Na+ expression

36
Q

_________ will increased number and type of receptors after nerve damage

A

demyelination

37
Q

T/F: Chemesthesis has a higher threshold for chemosensitivity than our sense of smell

A

true

38
Q

what is chemesthesis mediated by?

A

TRPV1 (V1) receptors

39
Q

Pain Perception Varies with ___________ Density

A

innervation

40
Q

what is TRPV1 sensitive to? What about TRPA1?

A

TRPV1:

  • capsaicin
  • noxious heat (above 42 degrees C)
  • protons

TRPA1: mustard oil, wasabi, garlic, noxious cold

41
Q

Lingual Chemesthesis (common chemical taste) is sensed by what type of fibers?

A

Trigeminal polymodal nociceptors (c-fibers)

42
Q

TRP receptors found on trigeminal sensory fibers respond to chemicals by mediate _________

A

chemesthesis

43
Q

what types of ion channels are found in the odontoblast?

A

1.TRP channels (TRPM3 and TRPV4)
sensitive to mechanical stimulation

  1. Voltage-gated Na+ channels
    (odontoblasts can generate action potentials)
44
Q

what neuropeptides do c-fibers release during thermal or mechanical injury?

A

releases neuropeptides substance P (SP) or CGRP

45
Q

T/F: Prostaglandins can stimulate a neuron

A

FALSE- Prostaglandins do not stimulate neuron

they lower its threshold to stimuli- sensitize the neuron

46
Q

what is the effect of CGRP being released from c-fibers?

A

vasodilation and swelling (mast cell activation)

from a mechanical activation of C-fibers

47
Q

_______ will stimulate c-fibers after an injury that causes bleeding

A

Bradykinin

48
Q

there is a upregulation of Na+ channels following what?

A

nerve damage sprouting

49
Q

how can the threshold limit for a nerve cell be lowered?

A

TRPV1- temperature threshold lowered by inflammation

Prostaglandins lower mechanical threshold via SK K+ channels

50
Q

which type of C-fiber will respond to only 1 type of nociceptive stimuli:

e.g. chemical, or thermal or mechanical only

A

non-polymodal

51
Q

what are trigeminal polymodal nocioceptors (c-fibers) sensitive to?

A
  • different spices

- high concentrations of salt