Physiology Of Pain 1

Question 1

A Alpha/ beta fibres are for?

Answer 1

Light touch, proprioception.

Large diameter, 30-75m/sec and myelinated

Question 2

A delta fibres are for?

Answer 2

Light touch, temp and nociception.

5-30m/sec, medium diameter, thin myelination

Question 3

C fibres are for?

Answer 3

Temperature, nociception. Small diameter, unmyelinated.

0.5-2m/sec

Question 4

What are meissners corpuscles for?

Answer 4

Stroking, fluttering

Question 5

Pacininan?

Answer 5

Vibration

Question 6

Merkel disks?

Answer 6

Pressure

Question 7

Ruffini endings?

Answer 7

Stretch

Question 8

Free nerve ending are by?

Answer 8

A delta/c receptors

Question 9

A delta fibres pain is…?

Answer 9

Well localised, activation of reflex arcs

Question 10

Visceral pain are solely activated by?

Answer 10

C fibres

Question 11

Hot temp channel? Agonist capsaicin.

Answer 11

TRPV1

Vanilloid subtype

Question 12

Cold channel, agonist menthol?

Answer 12

TRPM

Question 13

V COLD channel, cinnamon as agonist.

Answer 13

TRPA1

Question 14

How is prostaglandin formed?

Answer 14

From arachidonic acid by cyclooxygenase enzymes

Question 15

What does ATP switch on?

Answer 15

Purinergic receptors

Question 16

Neurogenic inflammation causes release of?

Answer 16

Substance P and calcitonin gene related peptide, leading to vasodilation and activation of mast cells

Question 17

Hyperalgesia?

Answer 17

Noxious stimuli produces an exaggerated response

Question 18

Allodynia?

Answer 18

Non-noxious stimuli produces a painful response

Question 19

Peripheral sensitisation happens through what?

Answer 19

1. Bradykinin
2. NGF
3. Prostaglandins

Question 20

What do Bradykinin and NGF do?

Answer 20

Reduce threshold of heat activated channels (TRPV1)

Question 21

What does prostaglandin do?

Answer 21

Reduce threshold of sodium channels

Question 22

Mechanism of action of bradykinin?

Answer 22

Bradykinin acts indirectly on TRPV1,
Binds to G receptor, activates protein kinase, phosphorylates TRPV1.

Phosphorylation reduces threshold, fires more easily

Question 23

First order neurons of spinothalamic tract?

Answer 23

Enter dorsal horn and form tract of lissauer and synapse in substantia gelatinosa releasing glutamate and substance P to excite second neuron

Question 24

Second order neurons?

Answer 24

Cross in dorsal horn and ascend anterolateral column to thalamus

Question 25

Sensory homunculus?

Answer 25

Lower body medial, upper body lateral

Question 26

Emotional component of pain?

Answer 26

Third order neurons project to insula and cingulate cortex

Question 27

How is stress induced analgesia caused?

Answer 27

Through descending modulatory pathways (periaqueductal grey matter) in midbrain and rostral ventromedial medulla

Question 28

Inhibition of pain happens how?

Answer 28

PAG excites serotnergic neurons in medulla which cause excitation of inhibitory interneurons in dorsal horn which inhibit spinothalamic tract neurons

Question 29

Opioids act where?

Answer 29

On inhibitory metabotropic receptors

Question 30

Cell body of nociceptors is where?

Answer 30

Dorsal root ganglion

Question 31

How does pressure transduction happen?

Answer 31

Mechanically sensitive ion channel, possibly acid sensing ion channels or transient receptor potential channels

Question 32

What can cause peripheral sensitisation?

Answer 32

Sunburn

Question 33

In the spinothalamic tract the first order neuron synapses where?

Answer 33

Substantia gelatinosa

Question 34

How does referred pain happen?

Answer 34

Due to convergence of visceral and cutaneous nociceptors on same second order neurons in spinal cord

Question 35

Which areas consist of the descending modulatory pathways?

Answer 35

Periaqueductal gray matter PAG

Rostrum ventromedial medulla RVM

Question 36

Where are opioids released from?

Answer 36

Interneurons

Question 37

Opioids do what in dorsal horn?

Answer 37

Inhibit second order neurons