Brainscape's Knowledge GenomeTM

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


See full index

M2 NENTE > 6.4 Pain Pathways > Flashcards

6.4 Pain Pathways Flashcards

1
Q

Aβ

  • Diameter (mm): 5-10
  • Conduction velocity (m/s): 40-75
  • Myelination: ___________
  • Modality: _______________
  • Threshold: _______
A

Thick;

Mechanoreception (light touch), Proprioception, Nociception (sometimes in chronic pain);

Low

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

Aδ

  • Diameter (mm): 2-5
  • Conduction velocity (m/s): 10-35
  • Myelination: _________
  • Modality: __________
  • Threshold: ________
A

Thin;

Thermoreception (cold), Mechanoreception, Nociception;

Intermediate

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

C

  • Diameter (mm): 0.5- 2
  • Conduction velocity (m/s): 0.5 -2
  • Myelination: _________
  • Modality: __________
  • Threshold: _______
A

None;

Thermoreception (warm), Nociception;

High

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

In the epidermis, dermis and subcutaneous tissue, there are free nerve endings from _____________
• Express receptors that detect noxious stimuli (nociceptors) → found in numerous tissues such as skin, muscle, joints, bone, visceral organs and meninges
• 4 classes of nociceptors which include _______________

A

unmyelinated C fibres and thinly myelinated Aδ fibres

mechanical, thermal, polymodal and silent

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

Mechanical receptor

  • type of fiber: __________
  • detects: _______
A

Free nerve endings of Aδ fibres;

Intense pressure

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

Thermal receptor

  • type of fiber: __________
  • detects: _______
A

Free nerve endings of Aδ fibres;

Extreme heat

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

Polymodal receptor

  • type of fiber: __________
  • detects: ______
A

Free nerve endings of C fibres;

Range of stimuli (noxious mechanical, thermal, chemical)

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

Silent receptor

  • type of fiber: __________
  • detects: ______
A

Free nerve endings of C fibres;

Mechanical and thermal stimuli (once chemically sensitised by inflammatory mediators)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Heat

  • Receptor
  • Receptor subunit
A
  • Transient receptor potential (TRP)

- TRPV1 (capsaicin-sensitive), TRPV2, 3, 4

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

Cold

  • Receptor
  • Receptor subunit
A
  • Transient receptor potential (TRP)

- TRPM8 (menthol-sensitive)

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

pH (acidic)

  • Receptor
  • Receptor subunit
A
  • Acid sensing ion channel (ASIC), Transient receptor potential (TRP)
  • TRPV1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Purine

  • Receptor
  • Receptor subunit
A
  • Purine receptors

- P2X

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

Mechanical

  • Receptor
  • Receptor subunit
A
  • Two-pore potassium channels

- K2P

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

During injury, there is quick onset of ________________ pain (lasting for short period of time) mediated by faster Aδ fibres:
• Later superseded by a second slower appearing _____________ pain mediated by slower C fibres

The origin of referred pain is usually distant from where it is perceived → commonly generated in a visceral organ but perceived on distant skin or muscle (e.g. neck pain in MI or shoulder pain in cholecystitis).

A

sharp and localised;

dull and poorly localisable

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

Where are nociceptor specific neurones found? What fibers do they synapse with? What do they respond to?

A
  • I and II (mostly), deeper laminae (some)
  • Synapse with Aδ and C fibres
  • Only respond to painful stimuli
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are wide dynamic range neurones found? What fibers do they synapse with? What do they respond to?

A
  • III to VI (mostly)
  • Synapse with all three types
  • Respond to full range of possible painful and non-painful stimuli
17
Q

Both nociceptive specific cells and wide dynamic range neurones are _____________ neurones → conduct the incoming nociceptive signal up to higher brain centres:
• Numerous projection neurones with different targets exist → most important ones are those projecting to the thalamus (spinothalamic tracts)
o Thalamus acts as the ______________, but pain pathways may also address other nuclei
• Some tracts address the brainstem (e.g. spinoreticular, spinomesencephalic tracts)

A

second order (projection);

main relay station

18
Q

From the thalamus, 3rd order neurones originate to transmit information to ________________ (pain matrix), and can use either a medial pathway originating from the medial thalamus or a lateral pathway coming from the lateral thalamus:

Destination:

  • Medial pathway: ______________
  • Lateral pathway: ________________
A

certain cortical areas;

Parts of the amygdala, Anterior cingulate cortex, Insular cortex;

Parts of the amygdala, S1 and S2

19
Q

Primary hyperalgesia

  • where does it occur
  • what is it caused by
A

Occurs only in the close vicinity of the damage and is caused by peripheral sensitization

20
Q

Secondary hyperalgesia

  • where does it occur
  • what is it caused by
A

Detected further away from the incision (covering a bigger area) and is caused by central sensitization

21
Q

The main cause of peripheral sensitization is the release of many inflammatory mediators as a consequence of the traumatic cell damage:
• Causes attraction of ____________ to the injury site and activation of the ______________
• Further mediator production and release → conglomerate of mediators (mediator soup) recruits more ____________ and lowers their activation threshold → increased number of impulses reaches the spinal cord and higher centres

A

mainly immune cells;

local autonomic nervous system;

nociceptors

22
Q

What substances are found in the mediator soup causing peripheral sensitisation?

A
  • TNFa
  • O*
  • Il- 6
  • H+
23
Q

What receptors do glutamate activate and what are their involvment?

A
  • AMPA (α-amino-3-hydroxy-5-methyl-4 isoxazeloproprionic acid) –> Acute pain transmission
  • NMDA (N-methyl-D-aspartate) –> Ongoing pain, Central sensitisation
  • Kainate
24
Q

What receptors do Substance P activate?

A
  • Neurokinin-1 –> Ongoing pain, Central sensitisation
25
Q

What receptors do CGRP (calcitonin gene-related peptide) activate?

A
  • Heteromeric complex of calcitonin receptor-like receptor & receptor activity modifying protein –> Ongoing pain, Central sensitisation
26
Q

What is the definition of wind up?

A

Increased synaptic transmission, but limited in space and time (affects only a limited number of primary afferents and their secondary neurones)
• Repeated stimulation causes a progressive increase in action potential firing

27
Q

What is definition of central sensitisation?

A

Increased synaptic transmission, but more complex and less limited in space and time (response to stimulus will outlast the stimulus):
• Increased transmission becomes autonomous (only requires a mild stimulus to trigger a full and lasting response)
• Changes in synaptic transmission spreads to other synapses → similar involvement of previously unaffected nociceptive and even non-nociceptive fibres → temporal and spatial amplification of incoming signals at the level of the spinal cord

28
Q

_____________ are the key to central sensitisation:
• Normally: _____________ keeps them closed
• If the cell is repeatedly stimulated: these plugs are increasingly removed → allows more and more calcium to enter the cell → activates intracellular cascades (as an intracellular messenger) → cell becomes more and more easily excitable

The consequences of central sensitization include secondary hyperalgesia and ___________ (previously innocuous stimulus now becomes painful):
• Best illustrated when patients complain that they cannot bear the feeling of bed linen or a T-shirt on their skin anymore

A

NMDA receptors (special glutamate receptors);

magnesium plug;

allodynia

29
Q

Descending inhibitory pathways originate in the ______, ______, ____, _________ after they receive indirect input from cortical areas:

  • Send projections to several relay stations from which the signal further descends
  • Main neurotransmitter of inhibitory descending pathways is noradrenaline → noradrenergic pathways originate (for example) from the _______ and address the dorsal horns
  • Endogenous opioidergic pathways descend from the ____________ to the dorsal horns where incoming primary afferents and outgoing secondary neurons possess ____________ receptors
  • __________ also contain nicotinic receptors (mediate antinociception) *All inhibitory mechanisms modulate synaptic transmission with the result of reducing the firing rate in ascending nociceptive pathways → limit incoming nociceptive stimuli
A

amygdala, thalamus, hypothalamus and reticular formation;

locus cerules;

periaqueductal grey

μ, δ and κ opioid;

Dorsal horns

30
Q

Descending facilitatory pathways originate in the _____________ in the medulla and the _______________ in the pons and address projection neurons in the dorsal horns:

  • Main pain-enhancing transmitter is serotonin → serotonergic pathways originate in the _________________ to enhance pro-nociceptive synaptic transmission in the spinal cord dorsal horns
  • However, the physiologic role of such pain enhancing pathways is still unclear
A

rostral ventromedial medulla;

parabrachial nucleus;

parabrachial-rostral ventromedial medulla complex

M2 NENTE (25 decks)

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