Exam 3 Week 13 ppt 6 Pain peripheral and central component

Question 1

Nociceptors are

Answer 1

unencapsulated endings that are categorized by the environmental stimulus

Question 2

Nociceptors responds to

Answer 2

mechanical, thermal, chemical or all of these (polymodal)

Question 3

Mechanical nociceptors- respond to

Answer 3

respond to intense mechanical stimuli

Question 4

Mechanical nociceptors- fibers

Answer 4

have small myelinated (Ad) afferent axons

Question 5

Thermal nociceptors- respond to

Answer 5

Respond to intense cold (below 5°C) or intense heat (above 45 C)

Question 6

Thermal nociceptors- fibers

Answer 6

have myelinated (Ad) or unmyelinated (C ) afferent axons

Question 7

Chemical nociceptors- respond to (3)

Answer 7

Respond to ions (K+ and H+), local inflammation mediators (histamine) and other chemicals (capsaicin)

Question 8

Polymodal nociceptors- respond to

Answer 8

Respond to mechanical, thermal or chemical stimuli

Question 9

Polymodal nociceptors- fibers

Answer 9

Small unmyelinated (C) afferent axons

Question 10

two calibers of nociceptive afferent fibers there lead to a theory called

Answer 10

phenomenon of Double pain

Question 11

phenomenon of Double pain (created by)

Answer 11

~First described by Lewis and Pochin (1937) where all the illustrations were labeled with their initials because they studied it by dropping hot metal on each other

Question 12

phenomenon of Double pain (details)

Answer 12

~Sharp, stabbing pain followed by burning and aching sensation
—-Fast (1st) pain – Ad fiber 1° afferent – small myelinated
—-Slow (2nd) pain – C fiber 1° afferent - small unmyelinated
~More of theoretical than practical value

Question 13

phenomenon of Double pain (details on fast pain)

Answer 13

~sharp stabbing pain or Fast (1st) pain arises from Ad fiber 1° afferent, small myelinated fibers

Question 14

phenomenon of Double pain (details on slow pain)

Answer 14

~achy burning pain or Slow (2nd) pain arises from the C fiber 1° afferent, the unmyelinated fibers

Question 15

3 different abnormal responses to stimulation of nociceptors

Answer 15

~peripheral sensitization
~hyperalgesia
~allodynia

(I’m pretty sure that hyeralgesia and allodynia are types of peripheral sensitization)

Question 16

Peripheral sensitization (general/ what is it)

Answer 16

~enhance responsiveness of nociceptors
~Increased sensitivity of nociceptors and primary afferents to noxious stimuli or a responsiveness of these receptors to non-noxious stimuli such as touch

Question 17

Hyperalgesia

Answer 17

Exaggerated sensitivity to noxious stimuli

Question 18

Allodynia

Answer 18

Normally innocuous stimuli evokes the perception of pain

Question 19

Peripheral sensitization can be produced by

Answer 19

~Local release of sensitization agents from mast cells

Question 20

examples of sensitization agents form mast cells (in peripheral sensitization)

Answer 20

~Prostaglandins
~Bradykinin
~Histamine
~Serotonin (5-HT)

Question 21

in peripheral sensitization, local release of sensitizing agents may produce

Answer 21

Axon reflexes where Antidromic impulses from 1° afferent will cause the release of substance P at distal ending producing inflammation

[An antidromic impulse in an axon refers to conduction opposite of the normal (orthodromic) direction[citation needed]. That is, it refers to conduction along the axon away from the axon terminal(s) and towards the soma.
(wikipedia)]

Question 22

Variety of nerve problems result in

Answer 22

pain

Question 23

most severe form of nerve pain is

Answer 23

ectopic pain

Question 24

Ectopic pain is

Answer 24

~activity along nociceptive afferents from site of damage not nerve terminal.
~results from a denuded axon
~can lead to an accumulation of Na+ channels in denuded area
~gives rise to an excitable area of axon

Question 25

ectopic pain (signs)

Answer 25

~positive Tinel’s sign over an unusual area of nerve | ~only light tapping over an area of inflammation can produce severe pain

Question 26

CRPS stands for

Answer 26

Complex Regional Pain Syndrome

Question 27

Complex Regional Pain Syndrome is

Answer 27

~severe chronic musculoskeletal pain syndrome | ~commonly seen in the extremities where non-nociceptive stimulation causes pain

Question 28

Complex Regional Pain Syndrome: 2 forms

Answer 28

Type 1 | Type 2

Question 29

Complex Regional Pain Syndrome- type 1

Answer 29

~not associated with demonstrable nerve lesions | ~formerly called reflex sympathetic dystrophy (RSD)

Question 30

Complex Regional Pain Syndrome- type 2

Answer 30

associated with nerve lesions formerly called causalgia

Question 31

Complex Regional Pain Syndrome- likely the results of

Answer 31

peripheral sensitization

Question 32

Myofascial Trigger Points

Answer 32

~Localized point pain generally in fascial covering of muscle or within muscle ~have been related to localized peripheral sensitization and axon reflexes

Question 33

Where do 1° nociceptive afferents synapse?

Answer 33

``` in the dorsal horn of the spinal cord, specifically in: ~Posteriomarginal nucleus ~Substantia gelatinosa ~Base of dorsal horn (lamina V) ~Some in ventral horn ```

Question 34

What type of axon fibers go to all areas

Answer 34

Neurons in all areas receive input from C fibers

Question 35

What type of axon fibers go to postero-marginal nucleus

Answer 35

receive Ad afferents

Question 36

What type of axon fibers go to lamina V

Answer 36

~receive Ad afferents | ~receive both nociceptive and low-threshold touch (Ab) input are referred to as wide, dynamic-range neurons (WDRNs)

Question 37

major 1° afferent excitatory transmitters on to central nervous system neurons are (2-4)

Answer 37

~glutamate (glut) ~substance P (SP) ~calcitonin gene related peptide (CFRP) and adenosine triphosphate (ATP) have been discovered to modulate 1° afferent input

Question 38

Primary afferent released Glutamate (glut) binds to

Answer 38

AMPA/KA receptors

Question 39

Primary afferent released Glutamate (glut) produce

Answer 39

fast EPSPs seen in post-synaptic neurons

Question 40

Primary afferent released Substance P (SP) produces and activates

Answer 40

produces slow EPSPs and actives 2nd messenger systems in the post-synaptic cells

Question 41

CFRP and ATP also appears to activate

Answer 41

2nd messenger intracellular systems

Question 42

GABA produces

Answer 42

both pre-synaptic and post-synaptic inhibition at these primary afferent terminals

Question 43

Serotonin (5-HT) and enkephalins (ENK) produce

Answer 43

post-synaptic inhibition

Question 44

A number of agents locally released by glial cells can

Answer 44

~increase presynaptic neurotransmitter release | ~increase post-synaptic excitability

Question 45

allodynia may develop in an area where (and causes)

Answer 45

~there is no apparent peripheral inflammation | ~painless stimuli are now experienced as painful

Question 46

allodynia is the result of

Answer 46

altered processing by of non-nociceptive input to wide, dynamic-range neurons (WDRN)

Question 47

central sensitization- suggested mechanism involves

Answer 47

~inputs to these wide, dynamic-range neurons ~input to WDR neurons through AMPA receptors from Ab afferents is minimal ~NMDA receptors for glutamate are blocked by the action of Mg++ ion

Question 48

central sensitization- activity of nociceptors is

Answer 48

~elevated and/or prolonged the Mg++ ion blockage is removed

Question 49

central sensitization- the activation of both AMPA and NMDA receptors causes

Answer 49

the non-nociceptive Ab fibers to activate pain pathways

Question 50

central sensitization- Ordinarily painless stimuli are experienced as -------- (why?)

Answer 50

**PAINFUL ~a negative from of synaptic plasticity that has resulted in the altered processing of non-nociceptive input to wide, dynamic-range neurons (WDRN) ~the result of pain now arising from non-nociceptive stimuli

Question 51

the nociceptive signals are relayed ____ by the ____ system

Answer 51

rostrally by the spinothalamic system – specifically by the lateral spinal thalamic tracts

Question 52

the nociceptive signal- many divide this pain pathway up into two subdivisions

Answer 52

the neospinothalamic component and the paleospinothalamic component

Question 53

the nociceptive signal- neospinothalamic component is composed of

Answer 53

neurons innervated by Ad afferent fibers.

Question 54

the nociceptive signal- neospinothalamic component signals travel to

Answer 54

VPL of the thalamus via anterolateral pathway (spinothalamic) and to 1° somatosensory cortex

Question 55

the nociceptive signal- neospinothalamic component mediates

Answer 55

~fast pain | ~sharp, well-localized, rapidly perceived pain

Question 56

the nociceptive signal- paleospinothalamic component is sometimes referred to as

Answer 56

Paramedial ascending system- PAS

Question 57

the nociceptive signal- paleospinothalamic component involves neurons actived by

Answer 57

the unmyelinated C primary afferent fibers

Question 58

the nociceptive signal- paleospinothalamic component rise through the

Answer 58

~ascending pathways initially rise in the lateral spinothalamic pathway

Question 59

the nociceptive signal- paleospinothalamic component projects to

Answer 59

~brainstem ~hypothalamus ~midline thalamus ~cingulate cortex

Question 60

the nociceptive signal- paleospinothalamic component mediates

Answer 60

~affective slow pain | ~poorly localized, emotional content of pain

Question 61

What does Antidromic mean?

Answer 61

An antidromic impulse in an axon refers to conduction opposite of the normal (orthodromic) direction[citation needed]. That is, it refers to conduction along the axon away from the axon terminal(s) and towards the soma. (wikipedia)

Question 62

what does denude mean

Answer 62

strip (something) of its covering, possessions, or assets; make bare. (so a denuded axon is probably an axon stripped of its myelin or something like that).

Question 63

what is reflex sympathetic dystrophy?

Answer 63

RSD is the former name for CRPS type 1 (lacks nerve lesions)

Question 64

what is causalgia?

Answer 64

the former name for CRPS type 2 (nerve lesions present)

Question 65

CFRP

Answer 65

calcitonin gene related peptide (CFRP) | one of the neurotransmitters that modulate 1* afferent input to the CNS