Pain Processing SEM2

Question 1

What is the role of the dorsal horn

Answer 1

Plays a role in pain and reflex pathways by receiving and sending signals to different parts of the CNS

Question 2

What are properties of A β fibres

Answer 2

Largely myelinated = faster nerve impulse transmission
Carries info related to non-painful stimuli - innocuous sensation

Question 3

What are properties of A δ fibres

Answer 3

Small myelinated
Transmits sharp pain - noxious sensation - nociception - pain
First pain

Question 4

What are properties of C fibres

Answer 4

Unmyelinated - slower impulse transmission
Transmit chronic pain/ ongoing pain
Dull, throbbing pain (second pain)

Question 5

Where is TRPV1 expressed

Answer 5

In small (C-fibre) dorsal root ganglion cells

Question 6

What does TRPV1 mediate

Answer 6

Mediates DRG cell responses to noxious heat, acidity and capsaicin

Question 7

What is the spinothalamic tract (STT) and its role

Answer 7

The STT is the main route to the thalamus and cortex
Carries somatotopic pain information (sensory info)

Question 8

What is the spinomesencephalic tract (SMT) and its role

Answer 8

SMT is an ascending pathway via parabrachial nucleus in brainstem to limbic regions, amygdala and hypothalamus

Question 9

What pathway modulates spinal pain processing

Answer 9

Descending pathways

Question 10

How can nerve injury cause chronic pain hypersensitivity

Answer 10

Na+ channels cluster at sites of nerve trauma and produce spontaneous action potential firing nociceptors

Question 11

How does inflammation/nerve injury cause repetitive firing in afferents

Answer 11

More Glu released
More AMPA R activation on spinal cord neurons
Depolarisation
Mg2+ is displaced (usually blocks NMDA R)