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Flashcards in Pain and Nociception Deck (27)
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1

How can pain be classified

Nociceptive pain and clinical pain

2

How can clinical pain be classified

Acute and chronic

3

What is nociceptive pain

Normal pain - mediated through As and C fibres
Only elicited when intense/noxious stimuli threaten to damage normal tissue
Protective function

4

Describe acute clinical pain

Results from soft tissue injury or inflammation
Serves as a protective function

5

Describe chronic clinical pain

A sustained sensory abnormality
Result of an ongoing peripheral pathology
Pain is maladaptive, offering no survival advantage

6

What are different attributes of pain as a symptom

Location
Quality - sharp stabbing, dull aching
Intensity
Frequency/duration
Provoking/relieving events

7

What is referred pain

Pain felt in one part of the body but the pathology is elsewhere
Pains tend to be referred to sites of common embryological origin
Due to a convergence of inputs in the CNS

8

What are nociceptor endings

Free nerve endings with a high threshold of activation that respond to intense noxious stimuli associated with pain

9

What nerve fibres are nociceptors

As fibres - noxious mechanical/heat
C fibres - polymodal - respond to quite a few stimuli which eventually lead to a dull, aching sensation

10

Give examples of different neural pathways in the CNS

Mechanoreception (touch)
Nociception (pain)

11

Which CNS relay nerves are involved in nociception

Spinal dorsal horn
Spinal trigeminal nucleus

12

Which CNS pathways are involved in nocicpetion

Spinothalamic tract
Anterior trigeminothalamic tract

13

Which areas of the forebrain are involved in nociception

Primary sensory cortex
Subcortical areas

14

What are factors that affect perception of pain

Genetic
Molecular
Cellular
Anatomical
Physiological
Psychological
Social

15

Describe the molecular basis of pain

SCN9A gene encodes a-subunit of voltage gated Na+ channel Nav1.7
Nav1.7 is strongly expressed in nociceptive afferents (receptor endings)
SCN9A mutation - loss of Nav1.7 function - inability to experience pain

16

Give examples of psychological factors in pain

Sex
Age
Cognitive levels
Previous pairs
Family
Culture

17

Give examples of situational factors in pain

Expectation
Control
Relevance

18

Give examples of emotional factors in pain

Fear
Anger
Frustration

19

Describe the gate control theory of pain

Rubbing sore areas lessens the perception of pain
Noxious stimuli activate C or As fibres which project into dorsal horn activating second order neurons which activate tertiary, eventually lessening the pain
Rubbing recruits Ab fibres, branch comes off called inhibitory interneurone which block activity of pain fibres so the pain disappears

20

What is the triple response

Mild trauma to the skin region, red line appears - the red line is the point of trauma - this is called the red reaction
The area around the skin appears very pale and swells up - this is wheal
After this, further away the skin appears red and discoloured - this is called flare

21

What occurs after mild trauma to the skin

Release of potassium, prostaglandins and bradykinin which are released from plasma if there is any damage to capillaries
There is also release of 5-HT from platelets
The nerve endings of skin can express substance P and CGRP

22

What does substance P and CPRG do to mast cells

Cause their degranulation

23

What does CPRG do

Causes dilation of blood vessels which is what gives rise to the flare region as there is more blood flowing through them making the skin appear red

24

What does substance P do

In the wheal region, the release of substance P causes plasma extravasation meaning they are leaky and it causes oedema

25

How can pain be stopped

Blocking conduction of action potentials

26

What’s the easiest way to stop an action potential

At the receptor ending
Can be done through anaesthetic

27

What do analgesics do

Block transmission of information from the 3rd order neurons to the sensory cortex