normal pain - modulation

Question 1

what is the action of opiod and gaba receptros

Answer 1

inhibitory

Question 2

what are some factors that modify ascending nociceptive transmission

Answer 2

pre + post synaptic receptors that mod ntsm release (opiods and gabas)
interneurons and descending neuron inputs

Question 3

what converges at the non-specific neurons in the dorsal horn (in gate theory)

Answer 3

nociceptive and non-nociceptive impulses

Question 4

what synapses with inhibitory interneurons (GC)

Answer 4

collateral fibres

Question 5

describe the excit/inhib effects of non-nociceptive and nociceptive fibres (GC)

Answer 5

large diameter non-noci excite inhibitory neurons

noci inhibit inhibitory neuroms

Question 6

what do relative frequnecies of aps in noci and non-noci fibres determine and what can this explain

Answer 6

how open the gate in spinal cord will be and how much pain info will pass
explain analgesic effects of rubbing skim, massage etc

Question 7

what type of control pathway is ‘diffuse noxious inhibitory controls’

Answer 7

descending pain control pathway

Question 8

how is diffusing noxious inhibitory controls induced

Answer 8

by the ascending pain pathway

Question 9

what is the pathway of diffusing noxious inhib controls that allows it to send efferent signals to various levels of the spinal cord

Answer 9

PAG -> nucleus-raphe magnus

Question 10

where can diffusing noxious inhib controls synapse

Answer 10

direct with 2nr order neurons
or
excite (disinhibit) opioidergic inhib interneurons, act both pre + post synaptically at spinal nociceptor synapse

Question 11

where can descending control pathways originate from

Answer 11

higher cortical centres via PAG

Question 12

what is the difference between an analgesic and anaesthetic

Answer 12

analgesic relieves pain without loss of consciousness

anaesthetic inhibit response to any stimulus and can result in loss of consciousness without the loss of vital functions

Question 13

what is the mechanism of function of NSAIDs

Answer 13

inhibit prostaglandin synthesis via inhibiting cox enzymes for prostaglandin synthesis
(in the periphery)

Question 14

where is paracetamol thought to act

Answer 14

CNS specific cos

Question 15

what is the mechanism of action of opioids

Answer 15

act via m-opioid receptors (agonists)
block ntsm release by:
inhib adenylate cyclase, inhib ca2+ influx, opens K+ channels

Question 16

where are opioid receptors located and what does their activation do

Answer 16

peripheral and central terminals of nociceptive afferent fibres -> reduced nociceptive signalling

Question 17

where can opioid analgesics also act

Answer 17

on inhibitory interneurons of brainstem to disinhibit the brainstem descending serotonergic pathway

Question 18

what is transcutaneous electrical nerve stim (TENS)

Answer 18

harnesses segmental control gate (gate control theory)

Question 19

what is the mechanism of action of local anaesthetics

Answer 19

inhibit Na influx, so aps can’t rise

Question 20

which fibres are sensitive to local anaesthetics

Answer 20

c and Adelta

Question 21

what are the methods for treating normal pain

Answer 21

paracetamol, nsaids, opioids, local anaesthetics, TENS