W5_07 Pain (Ballyk)

Question 1

define noxious

Answer 1

causing tissue damage

Question 2

define dysesthesia

Answer 2

abnormal unpleasant sensation

Question 3

define hyperalgesia

Answer 3

increased sensitivity to pain

Question 4

define allodynia

Answer 4

pain sensation elicited by a normally non painful stimulus

Question 5

difference between nociceptive pain and neuropathic pain?

Answer 5

nociceptive is normal pain (tissue damage or inflammation);

neuropathic pain is an issue with the reporting system

Question 6

what are the three types of nociceptors?

Answer 6

thermal;
mechanical;
polymodal

Question 7

thermal nociceptors are which kind of neuron fibre?

Answer 7

A delta

Question 8

mechanical nocicceptors are which kind of neuron fibre?

Answer 8

A delta

Question 9

polymodal nociceptors are which kind of neuron fibre?

Answer 9

C

Question 10

what are the differences between A delta and C fibres?

Answer 10

A delta: fast pain, localizable

C: slow pain, diffuse, evoke emotions

Question 11

what kinds of fibres encode touch?

Answer 11

A beta (to DC/ML)

Question 12

which two mechanisms cause inflammation?

Answer 12

axon reflex;

tissue damage

Question 13

which two molecules are released by nerve fibre collaterals to cause inflammation?

Answer 13

CGRP;

Substance P

Question 14

axon collaterals target which three structures to cause inflammation?

Answer 14

mast cells (histamine);
arterioles and capillaries (redness, heat, swelling);
platelets (serotonin or 5-HT release)

Question 15

histamine does what to nociceptors?

Answer 15

activate

Question 16

prostaglandin does what to nociceptors?

Answer 16

sensitize

Question 17

bradykinin does what to nociceptors?

Answer 17

activate

Question 18

potassium does what to nociceptors?

Answer 18

sensitize

Question 19

leukotriene does what to nociceptors?

Answer 19

sensitize

Question 20

serotoninn does what to nociceptors?

Answer 20

activate

Question 21

difference between axon reflex and damaged cell “reflex” on nociceptors?

Answer 21

axon reflex causes activation and cell reflex causes sensitization

Question 22

difference between 1º and 2º hyperalgesia?

Answer 22

1º = region of skin that is damaged;
2º = region of skin around damaged skin

Question 23

how do NSAIDs work?

Answer 23

block cyclo-oxygenase (COX);
thus decrease PGE;
thus decrease sensitization;
thus less pain

Question 24

naproxen and indomethacin are examples of what class of drugs?

Answer 24

NSAIDs

Question 25

how does referred pain work?

Answer 25

afferents from the skin and the viscera synapse on the same 2º spinal neuron in the dorsal horn

Question 26

how does touch inhibit pain?

Answer 26

while the A delta and C fibres are causing pain, A beta fibres activate interneurons that then inhibit activation of the 2º neuron in the dorsal horn.

Question 27

what are enkephalins?

Answer 27

endogenous opiods released from dorsal horn interneurons

Question 28

how do enkephalinergic interneurons inhibit pain?

Answer 28

these will prevent NT release in the 1º afferent nerve terminal and hyperpolarize the postsynaptic 2º neuron. they are activated by the descending periaqueductal grey neurons.

Question 29

what’s the wiring that causes an emotional response to pain?

Answer 29

spinal lemniscus neurons also send collaterals to reticular nuclei of the thalamus. the 3º neurons connect to cingulate gyrus (limbic system)

Question 30

diabetic neuropathy, trigeminal neuralgia, post-herpetic neuralgia, brachial plexus avulsion pain, spinal injury pain are examples of what kind of pain?

Answer 30

neuropathic pain (not nociceptive)