analgesia and anaesthesia

Question 1

2 modes by which opioids modulate pain transmission (act as analgesic)

Answer 1

decrease pain perception, increase pain tolerance (may dampen central pain perception also)

Question 2

pain perception pathway

Answer 2

painful stimulus -> nociceptor receptor on periphery (outside CNS) -> dorsal horn -> spinothalamic tract -> thalamus -> cortex

Question 3

opioid receptors in dorsal horn

Answer 3

u, k

Question 4

opioid receptor in thalamus

Answer 4

u

Question 5

opioid receptors in cortex

Answer 5

u, d

Question 6

pain tolerance pathway to suppress pain: locations

Answer 6

integrating centre is PAG (receives stimuli from regions of brain), NRPG (feedback part of brain that activates NRM), NRM (location which is activated by PAG and NRPG to cause pain suppression)

Question 7

pain tolerance: NRPG

Answer 7

in spinothalamic tract in spinal cord as pain stimulation goes to brain, stimulates NRPG (u,d) which stimulates NRM (d), which has negative feedback on dorsal horn (u,k)

Question 8

pain tolerance: PAG stimulation

Answer 8

thalamus and cortex (e.g. memory of same past painful stimuli e.g. twisted ankle) stimulate PAG (u,k), which stimulates NRM (d), which has negative feedback on dorsal horn (u,k)

Question 9

pain tolerance: PAG inhibitory

Answer 9

cortex (e.g. memory of same past painful stimuli) can inhibit PAG (u,k), causing decreased pain tolerance to flee from stimuli (e.g. wasp)

Question 10

S25

Answer 10

S25

Question 11

pain tolerance: LC

Answer 11

inhibits dorsal horn (u,k) as part of fight or flight response (so pain more after injury than during)

Question 12

pain tolerance: hypothalamus (k)

Answer 12

stimulates/inhibits PAG (u,k) based on health (if not dangerous but causing pain, will decrease pain tolerance to get you to stop, otherwise suppresses if in danger)

Question 13

role of substantia gelatinosa in pain transmission

Answer 13

modulates pain tolerance, which receives peripheral information from nerves and modifies signal (some signals still go straight to dorsal horn)

Question 14

locations of opioid action

Answer 14

dorsal horn, PAG, NRPG, periphery

Question 15

opioid action in dorsal horn and periphery

Answer 15

directly suppresses pain stimuli sensation before getting to spinothalamic tract

Question 16

opioid action in PAG and NRPG

Answer 16

disinhibition to allow PAG and NRPG to fire at a higher rate (by suppressing GABA)