neuroscience 11 - pain and nociception

Question 1

what type of pain can be associated with the pulp?

Answer 1

caries

dentine sensitivity

Question 2

define Pain

Answer 2

• An unpleasant sensory and emotional experience associated with actual or potential tissue damage

Question 3

define nociception

Answer 3

the activation of neural pathways by stimuli that damage or threaten to damage tissues

Question 4

Noxious Stimulus

Answer 4

potentially damaging stimulus

Question 5

Define nociceptive stimulus

Answer 5

a stimulus that activates nociceptive pathways

Question 6

why do we need pain?

Answer 6

usually signifies something is wrong ie caries abscess

Question 7

what are the 2 types of pain?

Answer 7

Acute

• fast sharp pain
• slow, burning pain

chronic

Question 8

describe the two dimensions of pain

Answer 8

sensory - discriminative
- quality, intensity and location
Affective
- emotional aspects

Question 9

what does the sensory nervous system inform the CNS of?

Answer 9

the internal and external environment

Question 10

what is the role of the nociceptive system?

Answer 10

to signal the threat or occurrence of injury

Question 11

where are nociceptors present?

Answer 11

throughout the body but esp in cornea and pulp - where pain is the predominant sensation

Question 12

where are nociceptors lacking?

Answer 12

brain, liver and lung parenchyma

Question 13

nociceptors can be classified by parent axons, describe Adelta fibres

Answer 13

Fine myelinated afferents
diameter = 1-5
conduction velocity 5-30 ms-1
fast sharp pain

Question 14

describe C fibres

Answer 14

fine unmyelinated afferents
dia
-diameter = 0.2 - 1.5
- conduction velocity: 5-30m-1
- slow burning pain

Question 15

which type of fibres are present in the tooth pulp?

Answer 15

A delta

Question 16

what do Adelta mechanical nociceptors respond to?

Answer 16

strong mechanical stimuli

Question 17

What do A delta polymodal nociceptors respond to?

Answer 17

all types of noxious stimuli

Question 18

C-fibre nociceptor

Answer 18

polymodal C-fibre nociceptors

Question 19

what happens in direct nociceptor transduction?

Answer 19

stimulus acts directly - mechanical, chemical and thermal

- membrane permeability changes - graded potential

Question 20

what is indirect nociceptor transduction?

Answer 20

• tissue injury/ inflammation

- chemicals released –> nerve ending

Question 21

local tissue damage produces chemicals - algogenic substances, what ions activate nociceptive nerve endings?

Answer 21

• ATP
• H
• K

Question 22

which algogenic subtances activate or sensitize nociceptive nerve endings?

Answer 22

• Bradykinin
• Serotonin
• histmaine

Question 23

which algogenic substances sensitise nerve endings?

Answer 23

• prostaglandins

Question 24

which chemical is released from nerve endings?

Answer 24

substance P

Question 25

what is the role of substance P?

Answer 25

• present in fine peripheral
  fibres
• role in central transmission

Question 26

How is Substance P released from free nerve endings?

Answer 26

• vasodilation
• Mast cell degranulation
• axon reflex

Question 27

define Allodynia

Answer 27

pain produced by a stimulus that would NOT normally produce pain

Question 28

what is the role of Cox inhibitors?

Answer 28

they block prostaglandin formation

Question 29

describe briefly the axon reflex

Answer 29

• response elicited by peripheral nerve stimulation

- impulses travelling along motor axons to activate local arterioles (to cause vasodilation)