Lecture 23 - Pain Flashcards Preview

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Flashcards in Lecture 23 - Pain Deck (24):
1

Three different types of pain

1) Nociceptive - a response to a noxious stimulus
2) Inflammatory - hyperalgesia during inflammation
3) Neuropathic

2

Acute nociceptive pain
1)
2)
3)

1) Immediate, short duration, localised
2) Activates nervous system
3) Reflex withdrawal response

3

Example of a nociceptor

Transient potential receptor subunit (An ion channel pore, TPRV1)

Activated by acid, capsaicin, temperature

4

Inflammatory mediator that is particularly good at inducing hyperalgesia

Prostaglandins

5

Substances that can lead to hyperalgesia

Histamine, bradykinin, prostaglandin, ATP, 5-HT, H+

6

Peripheral sensitisation
1)
2)
3)

1) Process of site of injury becoming more sensitive to pain
2) Early inflammation - Amplification of pain by reduction in receptor threshold and reduction in latency
3) Long-term changes - cytokine-, transcription factor-mediated. Leads to increase in number of receptors, neurotransmitters.

7

Allodynia

Pathological response to a light touch (pain when touched with a feather)

8

Nerve fibres that transmit pain signals
1)
2)

1) A delta
2) C

9

A delta-transmitted pain

Fast, sharp, acute, prickling pain.
Mechanical, thermal pain

10

C-transmitted pain

Slow, aching, throbbing, burning pain.
Chemical pain.

11

Synaptic receptors most implicated in pain

NMDA, AMPA

12

Excitatory neurotrasmitters

Glutamate, aspartate

13

Pain-associated synaptic receptor that has a low threshold

AMPA

14

Pain-associated synaptic receptor that has a high threshold

NMDA

15

How is NMDA activated?

Needs enough of a stimulus to remove Mg2+ cap from within ion channel

16

Effect of opioids

Act presynaptically to decrease neurotransmitter release
Act post-synaptically to hyperpolarise dorsal root neurons

17

Pain-associated fibres in the spinal cord, descending column

Noradrenergic, 5HT3

18

Spinal cord target for neuropathic pain

N-type voltage-gated calcium channel receptor.

19

Definition of chronic pain

Pain that continuous to be present more than three months after surgery or injury

20

Mutations in which protein can lead to chronic pain?

Sodium channel NaV1.7

21

Human gene associated with chronic pain

CACNG2 (stargazer gene)

22

Way to reduce risk of opioid dependence

Multimodal pain management.
Use smaller doses of opioids with other non-opioid analgesic drugs.
Target several parts of the pain pathway

23

Why can't opioids be used in pregnant women?

Foetal respiratory depression

24

Epidural

Inject analgesics into epidural space in spine