Pain and Thermosensation Flashcards

(52 cards)

1
Q

What are the 3 types of pain?

A

nociceptive pain; inflammatory and pathological

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

What are nociceptors?

A

specific peripheral primary sensory afferent neurones normally activated preferentially by intense noxious stimuli

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

Where are the cell bodies of nociceptors located?

A

dorsal root ganglia and trigeminal ganglia

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

What type of fibre are nociceptors?

A

Ad and C

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

What is the difference between the type of pain that Ad and C fibres carry?

A

Ad mediate first or fast pain whereas C fibres mediate slow pain

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

What type of sensations is first pain?

A

stabbing; pricking

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

What type of sensation is slow pain?

A

bruning; throbbing; cramping; aching

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

What type of stimuli do nociceptive Ad fibres respond to?

A

noxious mechanical and thermal stimuli

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

What ytpe of stimuli do nociceptive C fibres respond to?

A

all noxious stimuli- polymodal

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

What is frequency coding?

A

rate of AP discharge correlates with the intensity of the applied stimulus

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

What are the types of nociceptive Ad fibres?

A

type 1 (HTM) and type 2

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

What is the difference between the thresholds of heat required to activate type 1 and type 2 Ad fibres?

A

type 1- >53 whereas type 2 43-47

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

What type of fast pain do type 1 fibres mediate?

A

mechanical

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

What type of fast pain do type 2 fibres mediate?

A

heat

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

What happens to type 1 Ad fibres in response to prolonged stimuli?

A

show sensitisation

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

What are the types of C fibre?

A

C-MH; C-M; C-H and CMiHi

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

What are the features of C-MH fibres?

A

shows sensitisation to repeated stimuli and contributes to location of stimulus

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

What are the features of C-H fibres?

A

mediates heat hyperalgesia; acquires sensitivity to mechanical stimuli in inflammation

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

What are C-MiHi fibres?

A

normally insensitive to both mechanical and heat stimuli but acquires sensitivity through inflam mediators

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

How does the peripheral terminal of nociceptors influence local tissue environment?

A

releases molecules eg substance P and CGRP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does substance P do?

A

vasodilation and extravasation of plasam proteins

22
Q

What is CGRP?

A

calcitonin gene related peptide- vasodilation

23
Q

Where do nociceptors terminate in the spinal cord?

A

laminae of Rexed

24
Q

What do C and Ad fibres synapse with in the spinal cord?

A

nociceptive specific cells

25
What type of fibre do wide dynamic range neurones receive input from?
Ab; Ad and C
26
Where are the soma of the sensory neurones of the trigeminal system located?
trigeminal sesnory ganglion
27
What modality synapses in the chief sensory nucleus?
general tactile stimuli
28
What modality synapses in the spinal nucleus?
pain and temperature
29
How do peptides participate in neurotransmission?
cause a slow and prolonged epsp facilitating activation of NMDA receptors by relieving voltage-dependent blokc by magnesium
30
When do peptides mainly take part in neurotransmission?
during high frequency stimulation
31
Whta are the 2 types of sensisation of the nociceptive pathway following tissue damage?
peripheral and central
32
What mediates peripheral sensitisation?
nociceptors at the site of injury/tissue inflam
33
How does peripheral sensitisation cause primary hyperalgesia?
via reduced threshold and amplified response
34
What type of stimuli is peripheral sensitisation mainly involved in?
heat, to lesser extent mechanical
35
What mediates central sensitisation?
an increase in CNS neurone activity and properties
36
How does central sensitisation cause secondary hyperalgesia and allodynia?
recruitment of novel inputs to nociceptive pathways (eg Ab fibres) and abnormal processing of sensory input
37
What type of stimuli is central sensisation mainly involved in ?
mechanical sensitivity
38
How do visceral afferents from nociceptors reach the dorsal horn?
follow sympathetic pathways
39
What are the two nociceptive tracts i nthe spinal cord?
spinothalamic and spinoreticular
40
What type of pain does the spinothalamic tract carry?
fast fibre Ad pain and wide dynamic range
41
What does pain perception require in the spinothalamic tract?
simultaneious firing in both the Ad fibres and wide dynamic range neurones
42
What type of pain does the spinoreticular tract carry?
slow C-fibre pain
43
Where does the SRT connect?
reticular nuclei in the brainstem eg periaqueductal grey
44
What response to pain is the spinoreticular tract involved in?
autonomic respones to apin- arousal, emotional and fear
45
Where does the Spinoreticular tract relay information to after the thalamus?
limbic areas of the forebrain (cingulate and insular cortices and amygdala)
46
Where does the spinothalamic tract take pain signals after the thalamus?
primary sensorimotor cortices
47
How can pain evoked by acitivty in nociceptors be reduced?
simulatneous activity in LTMs (Ab fibres)
48
What is the gate control theory?
projection neurones to the spinothalamic tract receive inhibitory input from Ab and excitatroy input from C/Ad fibres- if both are Ab and Ad/C fibres are excited dont get pain
49
What area of the dorsal horn does the gate control theory take place?
substantia gelaninosa
50
What type of info does the ventral horn deal with ?
motor
51
How does TENS work?
Ab fibres can be activated by high freq, low intensity electrical stimulation through the skin, reducing the pain felt
52
What are thermoreceptors?
neurones specialised to respond to small changes in temperature