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

what are the dimensions of pain?

1) Acute vs. Chronic

2) Sensation of pain vs affective component

3) “Normal” vs Pathological Pain

2

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

sensation= Localization and intensity

affective component= Emotional response (psychological component)

3

how is "normal" pain mediated? how is pathological pain mediated?

"normal" pain- A-delta and c-fiber mediated


pathological pain- Peripheral & central sensitization

4

basic characteristics of A-delta fibers:

makes up 13% of cutaneous nociceptors

Small & lightly myelinated

responds to noxious mechanical stimuli

its the "1st pain- sharp and localized"

5

basic characteristics of C fibers

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

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

ENaCS :(epithelial sodium channels)

TRP (transient receptor potential) receptors

7

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

true

8

Chemesthesis is the response of _______ to chemical stimuli

c-fibers

9

what sensations are associated with chemesthesis

Burning & tingling


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

10

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

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

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

11

which branches of the Trigeminal nerve contains prominent chemesthesis sensation?

Nasal branch:
1) ethmoid

Oral branch:
1) Posterior palatine
2) Nasopalatine nerve
3) LINGUAL NERVE

12

Chemesthesis is Mediated by ______ receptors

TRP

13

Chemesthesis predominately transmits ______ sensations

aversive

e.g. burning, tingling
probably not "banana" or "salty"

14

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

A-delta fibers

-contain calcitonin gene related peptide (CGRP)
-mechanical & thermal sensitivity
-sharp pain

15

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

C fibers

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

16

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

C fibers

-has a long latency

17

which dentinal fibers respond to temperature?

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

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

EDTA dissolves smear layer

THEN pressure causes pain

19

T/F: there is communication between odontoblasts
and nerve terminals

False

Communication has not been demonstrated

20

what is the physiological evidence that supports the hydrodynamic theory?

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

Odontoblast may act as mechanoreceptor cell

21

what are the characteristics of Hyperalgesia?

-greater responsiveness to stimuli

-pain is spontaneous

-pain is prolonged

22

what is allodynia?

response to non-painful stimuli produce pain

23

___________ Mediators Affect Nociceptive Neurons

Inflammatory Mediators

24

which inflammatory mediators directly stimulate nocioceptors?

histamine
bradykinin
5-HT

25

which inflammatory mediators stimulate other cells to release algesics?

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


bradykinin: increases histamine release (mast cells)

26

_________ are inflammatory mediators involved in sensitization

prostaglandins

27

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

1. Ca++ activated
phosphorylation of VR1 receptor (TRPV1)

2. Increase in receptor number

3. Presence of inflammatory mediators (e.g.bradykinin & protons)

28

Sensitization of TRPV1 lowers the ___________ threshold

temperature

29

Sensitization by prostaglandins lowers the ___________ threshold

mechanical

30

Pain Pathophysiology associated with Nerve Damage:

1) Causalgia

2) Allodynia

3) Sympathetic nerve dystrophy - temperature induced pain

4) Phantom sensations - sensation in denervated tissue

31

Neuromas are caused by what?

collateral sprouting of nerve branches

(can be painful)

32

what are the characteristics of C-fiber ectopic discharge?

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

Ephaptic Transmission is a mechanism for which 2 conditions?

mechanism for allodynia and referred pain

34

what are the mechanisms for peripheral sensitization?

-Decreased threshold

-Pain is spontaneous & prolonged

-Ectopic discharge – (abnormal activation)

35

what is the mechanism for ectopic discharge?

more Na+ channels following nerve injury

response to catecholamines following nerve injury

Ephaptic response due to increased Na+ expression

36

_________ will increased number and type of receptors after nerve damage

demyelination

37

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

true

38

what is chemesthesis mediated by?

TRPV1 (V1) receptors

39

Pain Perception Varies with ___________ Density

innervation

40

what is TRPV1 sensitive to? What about TRPA1?

TRPV1:
-capsaicin
-noxious heat (above 42 degrees C)
-protons

TRPA1: mustard oil, wasabi, garlic, noxious cold

41

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

Trigeminal polymodal nociceptors (c-fibers)

42

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

chemesthesis

43

what types of ion channels are found in the odontoblast?

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

2. Voltage-gated Na+ channels
(odontoblasts can generate action potentials)

44

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

releases neuropeptides substance P (SP) or CGRP

45

T/F: Prostaglandins can stimulate a neuron

FALSE- Prostaglandins do not stimulate neuron

(they lower its threshold to stimuli- sensitize the neuron)

46

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

vasodilation and swelling (mast cell activation)


from a mechanical activation of C-fibers

47

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

Bradykinin

48

there is a upregulation of Na+ channels following what?

nerve damage sprouting

49

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

TRPV1- temperature threshold lowered by inflammation

Prostaglandins lower mechanical threshold via SK K+ channels

50

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

e.g. chemical, or thermal or mechanical only

non-polymodal

51

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

-different spices

-high concentrations of salt