Pathophysiology of pain

Question 1

what is pain

Answer 1

unpleasant sensation and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

Question 2

pain is perception is very ?

Answer 2

subjective

Question 3

What is dysesthesia?

Answer 3

any abnormal sensation described by a patient as unpleasant

Question 4

what is paresthesia?

Answer 4

a sensation that is typically described as “pins and needles” or “prickling”, but is not notably unpleasant

Question 5

what is analgesia?

Answer 5

reduction or loss of pain perception

Question 6

what is anaesthesia?

Answer 6

reduced perception of all touch and pain sensation

Question 7

what is the hypoalgesia?

Answer 7

decreased sensation and raised threshold to painful stimuli

Question 8

what is the hyperalgesia?

Answer 8

exaggerated pain response from a normally pain stimulus

Question 9

what is allodynia?

Answer 9

abnormal perception of pain from a normally non-painful mechanical or thermal stimulus

Question 10

what is hyperesthesia?

Answer 10

exaggerated perception of a touch stimulus

Question 11

what is causalgia

Answer 11

burning pain in the distribution of a peripheral nerve

Question 12

dermal pain tends to be described as ?

Answer 12

sharp or burning

Question 13

what are the types of nociceptors?

Answer 13

• thermal nociceptors
• mechanical nociceptors
• polymodal nociceptors
• silent nociceptors

Question 14

how are thermal nociceptors activated?

Answer 14

by temperatures > 45 degrees celsium or less than 5 degrees celsius

Question 15

how are mechanical nociceptors activated?

Answer 15

activated by intense pressure applied to a structure

Question 16

how are polymodal nociceptors activated?

Answer 16

activated by high intensity mechanical, chemical, or thermal stimuli

Question 17

what are silent nociceptors

Answer 17

receptors that are widely distributed through viscera that do not normally transmit pain information, only “awakened” in a setting of continuous damage or inflammation

Question 18

what are the two major types of fibres of nociceptors

Answer 18

C fibres and A-delta fibres

Question 19

what are C-fibres

Answer 19

unmyelinated axons with cell body in the dorsal root ganglia

Question 20

what are C-fibres responsible for?

Answer 20

conducting slow pain and thermoception (temperature), often dull, poorly-localized pain, C-fibres also carry itching sensations

Question 21

what are A-delta fibres?

Answer 21

myelinated axons with cell body in the dorsal root ganglia

Question 22

what are A-delta fibres responsible for?

Answer 22

conducting sharp, “pricking” pain as well as some thermoception (temperature)

Question 23

between C fibres and A-delta fibres, which one is well-localized and which one is poorly-localized pain?

Answer 23

C fibre is poorly-localized pain and A-delta fibres is well-localized

Question 24

what are transient-receptor potential receptors capable of recognizing?

Answer 24

• cold and heat
• low pH and free radicals
• capsaicin

Question 25

what is the major nociceptive sensory pathway?

Answer 25

spinothalamic tract

Question 26

peripheral afferent pain fibers of both A-δ and C types have their cell bodies in the

Answer 26

dorsal root ganglia

Question 27

what is fast pain?

Answer 27

well-localized, sharp pain carried by A-delta fibres

Question 28

what is slow pain?

Answer 28

poorer-localized, duller

Question 29

stimulation of certain brainstem areas can cause profound analgesia- the most famous of these brainstem areas is the ?

Answer 29

periaqueductal gray matter

Question 30

what receptors mediate the descending tract that directly inhibits pain conduction at the level of the spinal cord

Answer 30

opiate receptors

Question 31

what systems from the brainstem project to the spinal cord and activate inhibitory interneurons

Answer 31

norepinephrine and serotonergic systems

Question 32

what does norepinephrin and serotonergic systems release that both inhibit nociceptor presynaptic NT release and inhibit projection neurons

Answer 32

enkephalins

Question 33

what is the Gate Theory of Pain Control

Answer 33

Presence of non-nocieptive stimuli at a similar site/spinal level tends to reduce pain perception

Question 34

what is peripheral sensitization?

Answer 34

molecules released at the site of tissue damage or inflammation increase the effectiveness of nociception

Question 35

what is central sensitization?

Answer 35

occurs with synaptic remodelling in the dorsal horn – leads to increased effectiveness of pain transmission

Question 36

T or F: action potentials can actually move BOTH ways down a pain fibre

Answer 36

true

Question 37

what is orthodromic

Answer 37

action potentials from periphery -> spinal cord

Question 38

what is antidromic

Answer 38

action potentials from spinal cord -> periphery

Question 39

what does the P stand for in substance P

Answer 39

powder

Question 40

what releases substance P?

Answer 40

C fibres

Question 41

what is substance P and what does it bind to

Answer 41

Substance P is an 11 a.a. peptide and binds to the NK-1 (neurokinin-1) receptor

Question 42

do A-delta fibres release substance P?

Answer 42

no

Question 43

when substance P release what does it lead to?

Answer 43

long-lasting depolarization of projection neurons via modulation of other cation channels

Question 44

what is referred pain

Answer 44

○ tends to be referred not to the skin overlying the damaged organ but to other areas innervated by the same spinal segment