Neuro

Question 1

Cardiovascular effects to pain

Answer 1

Pain activates PAG, which activates RVLM (rostroventral lateral medulla) leading to activation of postganglionic sympathetic nerve fibres which innervate vascular tone leading to increased BP, HR

Question 2

Gate control theory

Answer 2

C unmylelinated fibres activate projection neurons and inhibit inhibitory interneurons which tonically inhibit projection neurons, leading to pain transmission. When Aa and Ab fibres are activated, they activate inhibitory interneurons causing decreased pain transmission from C fibres

Question 3

Endogenous opioids

Answer 3

3 families endogenous opioids: enkephalins, POMC, dynorphins
3 opioids receptors: mu, kappa, delta
Opiates bind to mu receptors, causing activation of descending to dorsal horn via 5-HT and NA pathways, from PAG and raphe nuclei of medulla. Inhibit projection neurons and activate enkephalin containing interneurons, reducing activity in nociceptive circuits

Question 4

Triple wheal repsonse

Answer 4

Tissue damage causes K+, prostaglandin release, ruptured BVs release bradykinin, ruptured platelets release 5-HT which activate free nerve endings
PA fibres activated, leading to mast cells releasing histamine
CGRP and substance P released
CGRP - vasodilation
Substance P - odema

Question 5

Ischaemic pain

Answer 5

Due to not enough O2 supply to tissues