PAIN HYPERSENSITIVITY - BIO&PHYSIOLOGY

Question 1

how does the nervous system act to protect and preserve to avoid furthur contact with noxious stimuli

Answer 1

threshold is lowered so nervous system is more sesitive
pain response to stimuli is enhanced and prolonged

Question 2

what can cause hypersensitivity

Answer 2

chemotherapy, diabeties, tumours, stroke

Question 3

what is hyperalgesia

Answer 3

pain in response to noxious stimuli with an exaggerated response

Question 4

describe the prostoglandin sensitisation pathway

Answer 4

PG’s produced from AA activae Gs G proteins
activates adenylyl cyclase - this converts ATP to cyclic AMP
cAMP activates protein kinase A
- facilitates VG Na+ channels
changes nociceptor excitability

Question 5

what activates acid sensitive ion channels

Answer 5

protons

Question 6

how does ATP become preswnt outside the cell

Answer 6

cell rupture

Question 7

when ATP enters extracellular fluid, what are the two receptors it can bind to and ehat type of receptors are these

Answer 7

P2 receptors
1) P2Y - G protein coupled receptor
2)P2X - ligand gated ion channel (P2X3 is the receptor involved i pain sensigtisiation

Question 8

what is bradykinin generated from

Answer 8

kininogen

Question 9

what receptor is involved in heat response

Answer 9

TrpV1 - Ca2+ ion channel

Question 10

how does bradykinin form

Answer 10

tissue damage leads to kininogen leaking from blood cells which bradykinin is generated from

Question 11

how does bradykinin increase sensitivity to heat

Answer 11

1) binds to bradykinin receptor 2
2) G G-protein activated
3) phospholipase C-beta activated
4) phospholipid PIP2 converted to diacylglycerol
5) protein kinase C-E form activated
6) TrpV1 phosphylated
the phosphorylated Ca2+ channel is more sensitive to heat stimuli as the thermal activation threshold has been lowered = inc response to heat

Question 12

what is peripheral sensitisation

Answer 12

reduction in threshold and an amplification in responsiveness of nociceptors

Question 13

when does peripheral sensitisation occour

Answer 13

when peripheral terminals are exposed to inflammatory mediators = hypersensitivity at sites of inflammation

Question 14

what is secondary hyperalgesia

Answer 14

spread of tension beyond lesion sites - ie PAIN EVERYWHERE

Question 15

what is central sensitisation

Answer 15

functional shift in the somatosensory system from high to low threshold pain hypersinsitivity in nociceptors

Question 16

what do the AMPA and NMDA receptor do

Answer 16

on postsynaptic terminal of projection neuron
glutamate (NT) receptors - when glutamatee binds they become permeable to cations such as Na+ andd Ca2+

Question 17

which receptor does ketamine block

Answer 17

NMDA