Lecture 25 - Pleasure and Pain I Flashcards Preview

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Flashcards in Lecture 25 - Pleasure and Pain I Deck (35)
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1
Q

Aspects of the pain experience
1)
2)
3)

A

1) Pain is always subjective
2) It is an experience
3) Relationship between pain and tissue damage is variable

2
Q

Way that touch and joint sense are projected to the brain
1)
2)

A

1) Receptors in skin project to dorsal column nuclei.

2) Dorsal column nuclei project to the thalamus via the Medial lemniscus

3
Q

Way that nociceptive signals project to the brain
1)
2)

A

1) Receptors in the skin project to neurons in the dorsal horn
2) Receptors in the dorsal horn project to thalamus, via the spinothalamic tract

4
Q

Example of nociceptors that project to the dorsal column

A

GIT nociceptors

5
Q
Cutaneous mechanoreceptors
1)
2)
3)
4)
5)
A

1) Hair follicles
2) Meissner corpuscle
3) Pacinian corpuscle
4) Merkel cell-neurite complex
5) Ruffini corpuscle

6
Q

Skin stimulus detected by Meissner corpuscle

A

Dynamic deformation. Objects slipping over skin.

7
Q

Skin stimulus detected by Pacinian corpuscle

A

Vibration

8
Q

Skin stimulus detected by Merkel cell-neurite complex

A

Indentation depth. For fine tactile discrimination.

9
Q

Skin stimulus detected by Ruffini corpuscle

A

Stretch.

10
Q

Two types of C-fibre mechanoreceptors

A

1) LTM, responsible for pleasant contact.

2) Polymodal nociceptor (with Adelta fibres)

11
Q

Example of a transducer in polymodal nociceptors

A

TRPV1

12
Q

TRPV1

A

A cation channel (Ca2+, Na+) in Adelta and C-fibres (nociceptors)

13
Q

Four functional types of nociceptors

A

1) Thermal (Adelta fibre)
2) Mechanical (Adelta fibre)
3) Polymodal (C-fibre)
4) Silent (C-fibre)

14
Q
Things that polymodal C-type fibres can detect
1)
2)
3)
4)
A

1) Noxious heat
2) Noxious cold
3) Peptidergic receptors (noxious peptides)
4) Nonpeptidergic

15
Q
Ion channel types in nociceptive neurons 
1)
2)
3)
4)
5)
A

1) Transient Receptor Potential channels (EG: TRPV1)
2) Voltage-gated Na+ channels
3) Hyperpolarisation-activated cation channels
4) K+ channels
5) Voltage-gated Ca2+ channels

16
Q

Functional difference between Adelta and C fibres

A

Adelta are larger, myelinated, faster conducting.

C-fibres are smaller, unmyelinated, slower conducting

17
Q

Silent nociceptors

A

C-fibres.

Not active in normal tissues. Activated when a tissue is damaged.

18
Q

Nociceptors in hairy skin

A

Adelta, C

19
Q

Nociceptors in glabrous skin

A

Only C-fibres

20
Q

Pain that Adelta are responsible for

A

Sharp pain

21
Q

Pain that C-fibres are responsible for

A

Slow, burning pain

22
Q

Differential projection of Adelta and C-fibres into the spinothalamic tract
1)
2)

A

1) C-fibres project to superficial layers (layers I and II)

2) Adelta project to deeper layers (IV, V)

23
Q

Proportion of neurons in the dorsal horn that project to the brain

A

5-10%

24
Q

Evidence that nociceptor activation doesn’t have to result in emotional response to pain

A

Reflex pathways of the dorsal horn

25
Q

What can lead to referred pain?

A

Two nociceptive inputs converging on the one spinal circuit

26
Q

Primary hyperalgesia

A

Tissue is damaged, leading to release of factors (EG: prostaglandin, bradykinin from mast cells).
This leads to nociceptors being easier to depolarise.

27
Q

Allodynia

A

Sensation of pain from light touch

28
Q

Difference between primary and secondary hyperalgesia

A

Primary occurs in the tissues that were damaged.

Secondary occurs in undamaged tissues surrounding damaged tissues

29
Q

Area responsible for sensory aspect of pain

A

Projections to primary somatosensory cortex

30
Q

What correlates with phantom limb pain?

A

Functional remodelling in brain of somatosensory cortex (detected with fMRI)

31
Q

Non-somatosensory parts of brain that are activated in nociception

A

Prefrontal cortex, anterior cortex, singulate cortex.

32
Q

Example of pain not correlating with tissue damage

A

Hot/cold grill results in sensation of burning heat

33
Q

Affective-motivational pain pathway

A

1) Anterolateral system
2) Middle thalamic nuclei
3) Insular cortex and anterior singulate gyrus

34
Q

Sensory-discriminative pain pathway
1)
2)
3)

A

1) Anterolateral system
2) Ventral posterior nucleus
3) Somatosensory cortex (S1, S2)

35
Q

Outcome of the complex network of centres stimulated by nociception in the brain.

A

Experience of pain is modulated by emotional factors
Positive emotion reduces unpleasantness of pain
Lack of attention to pain reduces intensity of pain