Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Nervous System (Semester 5) > 5.1: Neural Basis of Pain and Analgesia > Flashcards

5.1: Neural Basis of Pain and Analgesia Flashcards

1
Q

Define Nociception and Pain

What is the relationship between these?

A

Nociception: non-conscious neural traffic in response to (potential) trauma.

Pain: an unpleasant sensory and emotional experience associated with actual or potential tissue damage.

Nociception leads to pain BUT pain isn’t only nociception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How can pain be good and bad?

A

Pain can be good: stops us from hurting ourself (eg. putting hand on something hot)

Pain is bad because it is unpleasant to live with (eg. chronic pain can be extremely debilitating)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

List 4 other factors, in additon to nociception, that can lead to pain

A

1) Cognitive set: attention, distraction, catastrophising
2) Mood: depression, anxiety
3) Context: pain beliefs, placebo, expectation
4) Chemical and structure: neurodegeration, metabolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which gender and age group is most commonly affected by chronic pain?

A

Women and elderly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List 3 things chronic pain is associated with

A

1) increased mortality
2) worsening mental health
3) social deprivation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What parts of the brain are responsible for the following?

a) perception of pain
b) fear
c) memories
d) planning and reaction

A

a) somatosensory cortex
b) amygdala
c) hippocampus
d) prefrontal cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of nerves are pain nociceptors?

Give 3 stimuli they are sensitive to

A

They are free nerve endings

Sensitive to mechanical, thermal and/or chemical stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What kind of channels do pain nociceptors contain?

Name five factors that may potentially trigger these channels

A

TRP channels- cation channels (resemble voltage gated K+ channels but more unspecific)

Triggered by:

  1. Inflammation
  2. Injury
  3. Injury to CNS
  4. Nerve invasion (i.e cancer)
  5. Abnormal activity (i.e chronic regional pain syndrome)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is complex regional pain syndrome (CRPS)

A

A condition that causes severe pain which won’t go away

Eg. a minor injury such as a sprained ankle, where pain persists even after the injury has healed. This is because of abnormal healing processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the spinothalamic tracts responsible for?

A

Pain, temperature and crude touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define the sensation of crude touch

A

Being able to sense the feeling of touch without being able to localize where you were touched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What 2 fibre types transmit pain?

Compare these fibres

A

Pain is transmitted via Aδ and C fibres

Aδ fibres are myelinated and transmit fast, sharp and well localized pain

C fibres are unmyelinated and transmit slow, diffuse and dull pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the sensation of visceral organ pain and state 2 reasons why

A

Visceral/organ pain is diffuse and poorly localised

1) Organs have relatively few pain sensors
2) Enter the spinal cord at many levels, leading to potential crossing over of signals. This which is what results in ‘referred pain’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give 3 examples of reffered pain

A

1) Appendix pain: reffered from peri-umbilical area to RLQ
2) Flank pain from the kidney and/or radiating down the lower abdomen from the ureter
3) MI: pain presents in the upper chest, left arm, neck and lower jaw

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What theroy describes how the spinal cord modulates pain?

A

The gate theory of pain: suggests that stimulation of non-nociceptive receptors can inhibit transmission of nociceptive information in the dorsal horn.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain the Gate theory of pain (use the example of stubbing toe)

A

1) Painful stimuli (eg. stubbing toe) will stimulate first order nociceptor C fibres and Aδ fibres
2) These will synaps with the second order fibres in the substantia gelatinosa of the dorsal horn and carry the signal to the brain via the spinothalamic tract (perception of pain)
3) If we rub the area, we stimulate touch/pressure fibres
4) The touch pathway neurons activate an inhibitory interneuron which reduces ascending pain signals from the C fibres and Aδ fibres
5) This therefore reduces the sensation of pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name two ways the CNS can modulate pain

A

1) Endogenous opioids in brain and spinal cord
2) Central modulation/ descending signals from the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is central modulation of pain?

A

Involves descending analgesia producing pathways from the brain stem to the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Explain the pathway and mechanism of central modulation of pain

A

Periaqueductal grey matter (PAG) in midbrain ➞ through rostroventromedial medulla (RVM) ➞ into spinal cord

(receiving inputs from hippocampus, PFC, amygdala etc… as part of regulatory process)

down spinal cord to dorsal horn ➞ releases Serotonin & NA which stimulate interneurons to release Enkephalins, beta-endorphins and/or dynorphin

These bind opioid receptors ➞ inhibitory effect on synapses b/w 1st and 2nd order neurones of nociceptive pathways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Explain why we encourage patients with chronic pain (ie. Trigeminal neuralgia) to exercise?

A

Targeting the central modulation of pain! Excersise releases endorphins which can bind to the opioid receptors and help relieve pain

21
Q

Give 3 substances which bind opioid receptors

Give 2 substances which bind non-opioid receptors

A

Opioid: Enkephalins, beta-endorphins, dynorphin

Non-opioid: Serotonin and noradrenaline

22
Q

Define chronic pain and list 3 influential factors?

A

Any pain that lasts for more that 3 months past the normal healing time for an injury or disease

Has extensive psychological, social and economical factors

23
Q

List 3 broad catagories that may cause chronic pain and give 2 examples of each

A

1) Nociceptive/inflammatory

  • Osteoarthritis and Rheumatoid arthritis
  • Post-op pain

2) Neuropathic

  • Trigeminal neuralgia
  • Nerve injuries/ neuropathies

3) Idiopathic

  • Fibromyalgia
  • Irritable bowel disorders
24
Q

List 2 reasons we may have increased sensitisation to pain

A

1) increased activity of nociceptors
2) lower threshold of nociceptors

25
Q

Hyperalgesia and Allodynia are both examples of sensitisation, define and expalin each of these

A

Hyperalgesia: Increased pain from a stimulus that normally provokes pain due to an increased response at a normal threshold

  • Eg. a stimulus that would normally be perceived as slightly painful is perceived as significantly more so

Allodynia: Pain due to a stimulus that does not normally provoke pain due to increased excitability of neurons in the dorsal horn of the spinal cord (CNS)

  • Eg. perception of pain from something that is normally an innocuous stimulus (such as a feather)
26
Q

What is central sensitisation and what does this lead to?

A

Increased excitability of neurons in the dorsal horn of the spinal cord (CNS)

Leads to allodynia: perception of pain from something that is normally an innocuous stimulus

27
Q

Compare nociceptive vs neuropathic pain

A

Nociceptive pain is pain elicited by an INTACT nervous system

  • Pain pathways is acting normally, it is an actual stimulus affecting the nerve endings

Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system.

  • Can occur anywhere along the pain pathway
28
Q

Why can neuropathic pain be difficult to treat?

What 2 things commonly occur alongside neuropathic pain

A

Cannot be explained by a single disease process or specific location of damage

Neuropathic pain commonly occurs alongside hyperalgesia and allodynia

29
Q

Name 4 examples of neuropathic pain

A
  1. cancer
  2. phantom limb
  3. diabetes (diabetic neuropathy)
  4. MS
  5. spinal injury
  6. postherpetic neuralgia
30
Q

What causes postherpetic neuralgia and what is it?

A

Most common complication of shingles, it’s a condition affecting the nerve fibres on the skin which causes burning and pain lasting long after the shingles have disappeared

31
Q

Name 2 potential causes of neuropathic pain for each of the following locations:

a) thalamic/cortical level
b) brainstem
c) spinal level
d) peripheral level

A

a) Infarctions, tumors, MS
b) Infarctions (Wallenberg’s syndrome), tumors, MS
c) spinal cord injuries, MS
d) diabetic neuropathies, peripheral trauma, plexus avulsion, herpes zoster

32
Q

What is Wallenberg’s syndrome?

A

When an infarction or stroke occurs in the lateral medulla (part of the brainstem)

33
Q

Pathophysiology of neuropathic pain:

After a peripheral nerve injury sensitization occurs, give 6 things this can lead to:

A

1) decreased threshold of the nociceptor to activation
2) Increased receptive field of nociceptors
3) Allodynia and/or Hyperalgesia
4) Prolonged post stimulus sensations – hyperpathia
5) Emergence of spontaneous activity/increased excitability
6) Damaged peripheral nerves can develop abnormal Na+ channels which fire dysfunctionally and demonstrate different depolarisation properties

34
Q

Give 3 symptoms of neuropathic pain

A

1) Shooting and burning
2) Tingling and numbness
3) Unpredictable

35
Q

Give 2 treatments of neuropathic pain and explain the MoA of these

A

Amitriptyline: Tricycline which is an antidepressant

Duloxetine: NA/ Serotonin re-uptake inhibitor

Both of these increase the amount of Serotonin and NA that is available in the dorsal horn. This activates the inhibitory interneurons thus reducing the pain signals sent up the spinothalamic tract

(Non-pharmacological treatments must also be considered: eg psychological therapies)

36
Q

Explain the pathophysiology of chronic pain

A

Tissue injury (nociceptive) or nerve damage (neuropathic) causes persistent activation of pain pathway leading to:

Excess Glutamate release ➞ excess excitation of NMDA receptor ➞ excess 2nd order neurone firing ➞ ‘wind up’

Wind up results in long term hyper-excitability of 2nd order nociceptive neurones (respond at lower stimulus intensity) ➞ hyperalgesia & allodynia

Injury can also cause receptive field expansion at peripheral site

37
Q

Explain how wind up leads to receptive field expansion at the peripheral site

A

There is a certain amount of cross-over at the dorsal horn, so there is link between the second order neurones.

Normally a first order neurone will predominantly link to one second order neurone. However, with wind up stronger links form between first order neurones synapsing with two or three second order neurones

This causes expansion of the receptive field, making the location of pain perceived more diffuse

38
Q

Pain relief is multifactoral, not simply pain reduction

Give 4 other considerations we must make when treating pain

A

Context, cognition, mood, personality

39
Q

Give 5 types of analgesia

A
  1. Paracetamol
  2. NSAIDS
  3. Opioids
  4. Adjuvants
  5. Placebo
40
Q

Compare paracetamol vs NSAIDS

A

Both are COX enzyme inhibitors which block the formation of prostaglandins (trigger pain pathways at nerve endings) and thromboxane from arachidonic acids.

Paracetamol:

  • Main action is in the CNS
  • Has an analgesic and anti-pyretic effect (reduce temperature)

NSAIDS:

  • Main action is in the PNS
  • Has an analgesic, anti-pyretic AND anti-inflammatory effect
41
Q

Give 3 examples of an NSAID

A

Ibuprofen, naproxen and aspirin

42
Q

What is an Adjuvant?

Give an example

A

Adjuvants are drugs that have few or no pharmacological effects by themselves, but may increase the efficacy or potency of other drugs when given at the same time.

Eg. patients with arthritis may be given pain relief meds alongside corticosteriods (to reduce inflammation)

43
Q

Give 2 examples of the following analgesia:

  • Non-opioids
  • Weak opioids
  • Strong opioids
A

Non-opioid: Paracetamol, NSAIDs

Weak opioids: Codeine, Tramadol

Strong opioids: Morphine, diamorphine, fentanyl, alfentanyl

44
Q

Give 4 examples of an adjuvant

Give 4 examples of non-pharmacological analgesia

A

Adjuvants: Antidepressants, anticonvulsants, steroids, muscle relaxants, bisphosphonates, radiotherapy, nitrous oxide

Non-pharmacological: TENS, CBT, meditation, acupuncture, massage, hypnosis

45
Q

What 3 receptors do exogenous opioids bind and how does it work as an analgesia

A

Exogenous opioids interact with specific receptors:

  • μ (mu)
  • δ (delta)
  • ƙ (kappa)

This has an inhibitory effect on pain pathways and also has an central effect of creating a feeling of euphoria, which helps the patients short-term dealing with pain (this is a side effect)

46
Q

Give 4 side effects of exogenous opioids

A

Euphoria, sedation, respiratory depression, tolerance, miosis, nausea and vomiting, cough suppression, constipation, dependence, addiction

47
Q

Compare codeine vs morphine

Briefly explain how morphine works

A

Codeine: partial/weak mu-opioid receptor agonist

Morphine: full agonist at mu-opioid receptors in the CNS

  • Binds receptors in CNS involved in transmission and modulation of pain and dampens nerve signals transmitting pain
48
Q

What ‘effect’ demonstrates the higher brain functions and the complexity of pain in an individual

Give 2 examples of studies demostrating this effect

A

The placebo effect

Numerous studies:

  • Students and stimulants vs sedatives
  • Alcohol vs non-alcohol
  • Post-operative pain

Nervous System (Semester 5) (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions