Pain

Question 1

What is pain?

Answer 1

Unpleasant sensory and emotional experience

Associated with actual tissue damage or described in such terms

Question 2

What are the 3 types of pain?

Answer 2

Nociceptive
Inflammatory
Pathological

Question 3

Which of the 3 types of pain is maladaptive?

Answer 3

Pathological

Question 4

What is a nociceptor?

Answer 4

Peripheral primary sensory afferent neurones

Activated preferentially by intense noxious stimuli

Question 5

Why is (adaptive) pain important?

Answer 5

Early warning to detect and avoid contact with noxious events

Question 6

List the 2 subtypes of nociceptors

Answer 6

Aδ-fibres

C-fibres

Question 7

List 3 features of Aδ-fibres

Answer 7

Respond to thermal and mechanical stimuli
Myelinated
Mediate first pain

Question 8

List 3 features of C-fibres

Answer 8

Respond to all noxious stimuli (polymodal)
Unmyelinated
Mediate second pain

Question 9

Where are the cell bodies of nociceptors found?

Answer 9

Dorsal root ganglia

Question 10

Describe the nociceptive pathway from a peripheral site to the brain

Answer 10

Noxious stimulation on a free nerve ending
Transmission along nociceptor axon
Synapse with 2nd order neurone in dorsal horn of spinal column
Projected up to spinothalamic and spinoreticulothalamic tracts
Results in pain

Question 11

What are peptidergic C-fibres?

Answer 11

Subset of C-fibres

Have both afferent and efferent functions

Question 12

Which peptides cause the development of neurogenic inflammation?

Answer 12

Substance P (SP)
CGRP
- from peripheral terminals of peptidergic C-fibres

Question 13

Outline the development of neurogenic inflammation

Answer 13

SP causes
- vasodilation (CGRP also)
- histamine release from mast cells 
- sensitizes surrounding nociceptors
Primary and 2y hyperalgesia and allodynia ensue

Question 14

What is hyperalgesia?

Answer 14

Heightened sensitivity to noxious stimuli

Question 15

What is allodynia?

Answer 15

Pain elicited by innocuous stimuli