Lecture 3 Pain

Question 1

(Peripheral Nervous System) PNS Voltage Dependent Sodium Channels

Answer 1

NaV1.7 (TTX sensitive)
NaV1.8 (TTX resistant)
NaV1.9 (TTX resistant)

Question 2

Gain of Function in 1.7, 1.8, 1.9 Cause

Answer 2

PAIN

Question 3

Loss of function in Na1.7 results in

Answer 3

Loss of pain sensation

Question 4

Analgesic

Answer 4

drug that relieves pain without loss of consciousness

Question 5

Anesthesia

Answer 5

drug causing loss of all perception of sensory modalities

Question 6

Local Anesthetics

Answer 6

block nerve conduction (Lido)

Question 7

Endogenous Opioid Peptides (3)

Answer 7

-Endorphins
-Enkephalins
-Dynorphins or Neoendorphins

• brain and spinal cord nerves produce and secrete opioid peptides as neuromodulators.
• Released by pituitary and adrenal glands

Question 8

Opioid Receptor Location

Answer 8

Central or peripheral terminals of nociceptive afferents

Question 9

Opioid Peptides modulate nociceptive input in two ways :

Answer 9

1. Block neurotransmitter release by inhibiting Ca2+ influx
2. Open potassium channels: hyper polarizes neurons and inhibts pain fibers to conduct pain signal.

Question 10

Cannabinoids act as what type of receptors

Answer 10

Backwards Transmitters
- Retrograde; released by the postsynaptic cell act on presynaptic

Question 11

Gate control theory of pain

Answer 11

Activation of touch fibers inhibit the activation of pain fibers

Question 12

Presynaptic Gate control theory of pain

Answer 12

Ca channels down regulated

Question 13

Postsynaptic Gate control theory of pain

Answer 13

K channels are UP-regulated

Question 14

Descending control of pain

Answer 14

PAG-> LC +RVM->Dorsal Horn

Question 15

Important Notes on Descending control of pain

Answer 15

• RVM - has opioid receptors
• Opiates facilitate the off cells while inhibit the on cell
• Combination suppresses pain transmission in the dorsal horn.

Question 16

Somatosensory Cortex

Answer 16

• Fast Pain
• Localization of pain
• Little or no info about the magnitude of the pain

Question 17

Anterior Cingulate Cortex

Answer 17

• Slow Pain
• Perception of the emotional component of pain (unpleasantness)
• Sends output to PAG to suppress ascending pain information.

Question 18

Insular Cortex

Answer 18

• Pain Consciousness, especially visceral pain
• Interconnections with the Amygdala (Intense emotion)