Exam #6: Sensory Physiology of Pain Flashcards Preview

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Flashcards in Exam #6: Sensory Physiology of Pain Deck (61):
1

Why is chronic pain important?

- 30% US population experiences chronic pain
- Leading neurological disorder & high cost to society
- Leading cause of disability & suffering

2

What is the difference between nociception & pain?

Nociception= sensory response to a noxious stimulus

Pain= perception of nociceptive sensory information

3

What are the two components of pain?

1) Sensory-discrimination= perception of external or internal noxious stimuli & the localization to the site of the stimulus

2) Motivation-affective= emotional & sympathetic responses associated with behavior

4

What brain regions are associated with sensory discrimination?

Primary & secondary somatosensory cortices

5

What brain regions are associated with the motivational-affective component of pain?

Frontal cortex
Limbic system
Brainstem

6

What type of sensory information associated with the sensory-discriminative component of pain?

Location
Intensity
Modality (e.g. stab vs. burn)

7

What type of information is conveyed by the emotional component of pain?

- Negative impact on mood
- Depression associated with chronic pain

8

What is acute pain? What are the functions of acute pain?

- Body's warning signal that is critical for survival
- Pain felt within 0.1 sec of stimulus i.e. VERY FAST
- Very adaptive i.e. tissue heals and pain abates

9

What fibers conduct acute pain?

A-delta

10

What is pathologic or chronic pain?

- Pain that begins >1 sec after stimulus and then progressively worsens
- Can become MALADAPTIVE i.e. persists even if there is no more tissue damage

11

What fibers conduct pathologic pain?

Persistent and SLOW conducting C-fibers
- small
- unmyelianted

12

What are the qualities of acute pain?

Sharp
Prickling
Electric
Cutting

13

What are the qualities of chronic pain?

Dull
Throbbing
Aching
Nauseous

14

What is nocicpetive pain?

Physiologic pain that serves as a warning to the body

15

What is inflammatory pain?

Pain that is associated with healing

16

What is dysfunctional pain?

Pain without an underlying lesion or that is disproportionate to tissue injury
- IBS
- Fibromyalgia

17

What is neuropathic pain?

Pain from damage to the CNS or PNS that is disproportionate to intensity of nociceptor activation

18

What is the difference between somatic and visceral pain?

Somatic= superficial or deep pain originating from the body

Visceral= pain originating from internal organs

19

What is the difference between the fibers that mediate somatic and visceral pain?

Somatic= A-delta
Visceral= C

20

What are the four general steps from external injury to perception of pain?

1) Transduction
2) Transmission
3) Modulation
4) Perception

21

What is peripheral transduction?

Conversion of injury to electrical stimulus

22

What type of receptors are nociceptors?

Free-nerve endings

23

Where are the soma of nociceptions in the body vs. the face?

Body= DRG
Face= Trigeminal ganglia

24

What are the important functional characteristics of nociceptors?

- High threshold
- Slowly adapting

25

What stimuli can activate nociceptors?

- Mechanical (of high intensity)
- Thermal
- Chemical

26

What are the different types of thermal nociceptors?

CMR-1= cold
VRL-1= noxious heat
VR-1= noxisous heat/ capsaicin

27

What is "inflammatory soup?"

Tissue injury resulting in the release of a number of inflammatory mediators

*****These inflammatory mediators stimulate nociceptors & lead to indirect sensitization or LOWERED THRESHOLD

28

What is peripheral sensitization?

1) Lowered threshold of activation for nociceptors in response to injury
- Increased sensitivity of neurons directly involved
- Increased sensitivity of a wider area of tissue

2) Activation of silent nocicpetors

29

What NT plays the largest role in peripheral sensitization?

Substance P

30

What is allodynia?

Pain resulting from non-noxious stimuli

31

What is hyperalgesia?

Increased response to a stimulus that is normally painful

32

What is axon reflex?

Coupling of sensory system to the SNS in response to inflammatory mediators

33

What is the triple response of Lewis?

Redness
Edema
Wheal

34

What is the difference between A-delta & C fibers?

A-delta= myelinated--faster
- localized
- sharp
- "first" pain

C= unmyelinated--slower
- poorly localized/ diffuse
- polymodal
- "second" pain

35

What types of fibers are associated with the cutaneous tissue?

A-delta & C

36

How do joints and muscles differ from cutaneous tissue in regards to fiber types?

2x as many C fibers compared to A-delta

37

What fiber types are present in the viscera?

Predominantly C-fibers

38

What happens in the dorsal horn of the spinal cord in the transmission of pain?

Synapse from 1st order neuron to dorsal horn 2nd order neuron

39

What tracts carry nociceptive information in the spinal cord?

Spinothalamic tracts

40

What lamina are associated with A-delta fibers vs. C?

A-delta= Lamina I
C= Lamina II & III

41

What are WDRs?

Polymodal second order neurons that can respond to noxious stimuli and other stimuli

42

What NT is being release at the synapse between first & second order neurons in the spinal cord? What receptors are on the second order dendrite?

Glutamate=
- NMDA
- AMPA

43

Recall, what kind of threshold do A-delta & C fibers have?

High-threshold

44

What is central sensitization?

Amplification of pain signaling in the spinal cord

45

What is secondary hyperalgesia?

Prolonged & increased activation of nocicpetors in the periphery & projection pathways in the spinal cord
- Recruitment of adjacent areas
- Increased release of NT

46

What NT & receptor type underlies secondary hyperalgesia?

Glutamate & NMDA-R

47

What is neuronal plasticity?

Modulation of intracellular signaling & changes in gene expression

48

What does neuronal plasticity underlie in respect of pain?

Memories of pain & the lasting effects of chronic pain

49

What sensations are carried by the DC/ML?

Discriminative Touch
Proprioception

50

What sensations are carried by the AL system?

Temp.
Pain
Crude touch

51

What is the neospinothalamic tract?

- Pathway of pain from A-delta fibers
- Lamina I, IV, V

52

What information is carried by the neospinothalamic tract?

Sensory-discriminative

53

What is the paleospinothalamic tract?

- Slow type C fibers
- Lamina II, III, V

54

What information is carried by the paleospinothalamic tract?

Emotional/ affective

55

What is the function of the spinoreticular tract in pain?

Motor response to pain i.e. descending pain control

56

What is the function of the spinomesencephallic tract in pain?

Descending pain control, particularly eye movements and regulation of gaze to site of injury via the superior colliculus

57

Where in the brain does the perception of pain occur?

Sensory= somatosensory association cortex

Emotional= insular cortex & anterior cingulate cortex

Cognitive= prefrotnal cortex

58

What does the anterior cingulate cortex (ACC) contribute in terms of pain?

Attention to pain

*****Conscious activation of the ACC can dampen pain signaling

59

When is the ACC most active?

1) Perception of pain
2) Imagining pain
3) Observation of pain in others

60

What is the Gate Control Theory?

Generally, this is distraction
- A-beta (mechanoreceptor/ proprioceptor) activation inhibits C-fiber transmission

61

What is descending pain control?

Endogenous mechanism in the body to regulate pain

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