NB10

Question 1

What is the name for pain receptors

Answer 1

Nociceptors

Question 2

What are the chemical stimuli released from damaged cells

Answer 2

Bradykinins
Prostaglandins
H+
ATP

Question 3

What are the chemical stimuli released from platelets

Answer 3

Serotonin

Question 4

What are the chemical stimuli released from immune cells

Answer 4

Cytokines

Chemokines

Question 5

Cold receptor

Answer 5

TRP A1
TRP M8
trp - Transient Receptor Potential

Question 6

Heat receptor

Answer 6

TRP V1

Question 7

Protons receptor

Answer 7

ASIC

acid-sensing ion channel

Question 8

Bradykinin receptor

Answer 8

B1/B2

Question 9

Mechanical receptor

Answer 9

DRASIC/mDEG
dorsal root acid-sensing ion channel
mammalian degenerin

Question 10

What type of fibres are there

Answer 10

1. Aδ fibres

2. C fibres

Question 11

What are Aδ fibres

Answer 11

• Produces sharp, localised, immediate pain
• Relay info via thalamus to cortex and trigger immediate withdrawal and allow localisation of pain
• Small, myelinated fibres
• Speed of conduction: 12-30m/s

Question 12

What are C fibres

Answer 12

• Produces dull, diffuse pain
• Relay info to the limbic system and hypothalamus (triggering memory of stimulus and emotional response)
• Small, unmyelinated fibres
• Speed of conduction: 0.5-2m/s

Question 13

Pain pathways

Answer 13

1. Primary pain afferent to spinal cord
2. Spinothalamic tract to thalamus
3. Thalamus to sensory cortex

*pain from face (cranial nerve) bypasses the spinal cord

Question 14

Nociceptive fibres in spinal cord dorsal horn

Answer 14

1. On entering spinal cord, Aδ and C fibres ascend in tract of Lissauer
2. They synapse with 2nd order neurones in superfiila layers of dorsal horn:
   - Aδ = layers I and V (limited in II)
   - C = layers II (substantia gelatinosa)
3. Decussation of ascending 2nd order neurones carrying pain or temperature info occurs immediately

Question 15

Neurotransmitters involved in pain

afferent terminal of primary sensory neurone to dorsal horn neurone in spinal cord

Answer 15

Glutamate - NMDA, AMPA

Substance P - NK1

Question 16

Inhibitors of pain receptor

Answer 16

GABA
Opiods
eCBs (endocannabinoids)
-inhibitory neurons in substanstia gelatonisa (layer II)

Question 17

Where is endogenous opiods released

Answer 17

At sites associated with modulation of pain and act on opioid receptors

Question 18

How are opioid receptors classified

Answer 18

1. μ (heat)
   - β-Endorphin and Leu-Enkephalins
2. δ (mechanical)
   - Leu and Met-Enkephalins
3. κ (visceral)
   - Dynorphin

Question 19

Example of eCBs (endocannabinoids)

Answer 19

Anandamide

2-arachidonylglycerol

Question 20

What are eCBs (endocannabinoids) derived from

Answer 20

arachidonic acid derivatives

Question 21

How does eCBs (endocannabinoids) mediate their effects

Answer 21

Anagelsic effect mediated via activation of cannabinoid receptors:
CB1 - brain, spinal cord, dorsal root ganglion neurons
CB2 - immune cells
-reduce NT release
-reduce Ca2+ in presynaptic terminal

Question 22

What are the responses to painful stimuli

Answer 22

1. Concious perception of pain
2. Spinal withdrawal reflex
3. ANS changes
4. Emotional response

Question 23

What happens when reticular formation is activated by pain fibres

Answer 23

Increase alertness

raphe nuclei - increase serotonin production

Question 24

What happens when pain receptors activates thalamus

Answer 24

Perception of pain

Question 25

What happens when pain receptors which activate thalamus and reticular formation activates the hypothalamus and limbic system

Answer 25

Behavioral and emotional responses to pain

Question 26

What happens when activated thalamus (by pain fibres) activate somatosensory cortex

Answer 26

Localisation of pain

Question 27

What is visceral pain

Answer 27

Poorly localised - felt in areas removed from site of stimulus - referred to somatic structures - due to convergence of visceral and somatic afferents on dorsal horn neurones and the brain interprets the signals as coming from somatic structure

Question 28

Where does pain from heart referred to

Answer 28

Left arm

Question 29

Where does pain from liver and gallbladder referred to

Answer 29

Right neck and shoulder Right below the right breast *note: both anterior and posterior

Question 30

Where does pain from lung and diaphragm referred to

Answer 30

Left neck and shoulder

Question 31

Where does pain from ureter referred to

Answer 31

Anterior groin area

Question 32

Where does pain from colon referred to

Answer 32

Anterior suprapubic region

Question 33

Where does pain from urinary bladder referred to

Answer 33

Anterior pubic region | Midline of butt

Question 34

Where does pain from stomach referred to

Answer 34

Epigastric region | Midline of the back

Question 35

What is gate theory

Answer 35

modulation of pain perception in dorsal horn of spinal cord Somatic non-painful signals can inhibit transmission of pain signals in the spinal cord (analgesia) - large diameters Aα and Aβ fibres carrying touch, pressure, vibration, temperature - stimulate inhibitory interneurons in the substantia gelatinosa - inhibit transmission of pain at the synapse between 1st and 2nd order neurons - GABA and endogenous opioids are released

Question 36

Descending/Analgesic pathway

Answer 36

1. Neurons from PAG (periaqueductal gray matter) activate reticular formation and stimulate the release of endogenous opioids 2. Binds to opiate receptor 3. Inhibits release of substance P from afferent pain fibres 4. Transmission of pain impulsese to brain blocked 5. No perception of pain at thalamus PAG - has enkephalin-producing cells which binds to opioid receptors

Question 37

Neurotransmitter involved in descending control

Answer 37

Serotonin | Noradrenaline

Question 38

Origin of descending modulating pathways

Answer 38

1. Peri-ventricular and peri-aqueductal grey matter in midbrain 2. Rostroventral medulla including raphe nuclei

Question 39

Paresthesia

Answer 39

Pins and needles

Question 40

Dysesthesia

Answer 40

Burning sensation

Question 41

Hyperalgesia

Answer 41

Lower pain threshold or exaggerated pain response to noxious stimulus

Question 42

Allodynia

Answer 42

Pain in response to a non-noxious stimulus

Question 43

Deafferentation pain

Answer 43

Peripheral nerve lesions such as phantom limb pain

Question 44

Psychogenic pain

Answer 44

Occuring with or without an organic cause or disproportionate to the organic cause