7. Pain

Question 1

What is the name given to pain receptors?

Answer 1

Nociceptors

Question 2

What kind of stimuli do nociceptors react to?

Answer 2

Mechanical
Chemical
Thermal

Question 3

What sources do chemical stimuli come from?

Answer 3

Damaged cells
Platelets
Immune cells

Question 4

What chemicals are released from damaged cells?

Answer 4

Bradykinins
ATP
Prostaglandins
H+

Question 5

What chemical is released from platelets?

Answer 5

Serotonin

Question 6

What chemicals are released from immune cells?

Answer 6

Cytokines

Chemokines

Question 7

Which receptors detect cold?

Answer 7

TRP A1

TRP M8

Question 8

What receptor detects heat?

Answer 8

TRPV1

Question 9

What receptor detects protons?

Answer 9

ASIC

Question 10

What receptor detects bradykinin?

Answer 10

B1

B2

Question 11

Which receptors detects mechanical stimuli?

Answer 11

DRASIC

mDEG

Question 12

What kind of fibres are type 1 pain fibres?

Answer 12

A-delta

Small, myelinated, fast conduction

Question 13

What sort of pain is transmitted through A-delta fibres?

Answer 13

Sharp, localised and immediate

Question 14

Where does information from A-delta fibres go?

Answer 14

Thalamus and cortex

Question 15

What NT is used in A-delta fibres?

Answer 15

Glutamate

Question 16

What kind of fibres are type 2 pain fibres?

Answer 16

C

Small, unmyelinated, slow conduction

Question 17

What sort of pain is transmitted through C fibres?

Answer 17

Dull, aching pain

Question 18

Where does information from C fibres go?

Answer 18

Limbic system

Hypothalamus

Question 19

What NT is used in C fibres?

Answer 19

Substance P

Question 20

Which sensory pathway does pain travel in?

Answer 20

Spinothalamic

Question 21

What tract in the spinal cord do A-delta and C fibres ascend in?

Answer 21

Tract of Lissauer

Question 22

Where do A-delta fibres synapse in the dorsal horn?

Answer 22

Layers I and V

Question 23

Where do C fibres synapse in the dorsal horn?

Answer 23

Layer II (Substantia gelatinosa)

Question 24

When do the pain fibres decussate?

Answer 24

Immediately after synapsing with the second order neuron

Question 25

Which receptors does glutamate act on?

Answer 25

NMDA | AMPA

Question 26

Which receptor does Substance P act on?

Answer 26

NK1

Question 27

What are endogenous opioids?

Answer 27

Chemicals released to help modulate pain

Question 28

What are the 3 types of opioid receptors?

Answer 28

μ (heat) δ (Mechanical) κ (Visceral)

Question 29

What endogenous opioids are released in response to heat?

Answer 29

β-Endorphin | Leu-Enkephalin

Question 30

What endogenous opioids are released in response to mechanical stimuli?

Answer 30

Leu-Enkephalin | Met-Enkephalin

Question 31

What endogenous opioids are released in response to visceral stimuli?

Answer 31

Dynorphin

Question 32

Name 2 endocannabinoids

Answer 32

Anandamide | 2-arachiodonylglycerol (2-AG)

Question 33

What are endocannabinoids derived from?

Answer 33

Arachidonic acid

Question 34

Which receptors do endocannabinoids work on?

Answer 34

CB1 (CNS) | CB2 (immune cells)

Question 35

How do endocannabinoids mediate their analgesic effect?

Answer 35

Reduce Ca++ in presynaptic neuron to reduce NT release

Question 36

What is gate theory?

Answer 36

Non-pain signals can inhibit the transmission of pain signals

Question 37

How does gate theory work?

Answer 37

Large diameter Aα and Aβ fibres carrying non-pain stimuli stimulate interneurons in the substantia gelatinosa Inhibit the transmission of pain between the 1st and 2nd order neurons using GABA and endogenous opioids

Question 38

What are the origins of pathways that modulate pain?

Answer 38

``` Peri-ventricular and peri-aqueductal grey matter in the midbrain Rostroventral medulla (raphe nuclei) ```

Question 39

Which NTs help in the modulation of pain?

Answer 39

Serotonin | Noradrenaline

Question 40

What is meant by paresthesia?

Answer 40

Pins and needles

Question 41

What is meant by dysesthesia?

Answer 41

Burning sensation

Question 42

What is meant by hyperalgesia?

Answer 42

Low pain threshold or exaggerated pain response

Question 43

What is meant by allodynia?

Answer 43

Pain in response to a stimulus that doesn't usually cause pain

Question 44

What is meant by deafferention pain?

Answer 44

Peripheral nerve lesions | Eg. Phantom limb

Question 45

What is meant by psychogenic pain?

Answer 45

Pain that occurs with or without an organic cause, may be disproportionate to the organic cause