Pain

Question 1

Define pain

Answer 1

Sensory + emotional experience associated with actual / potential tissue damage
Individual is expert on their own pain
Acute + persistent pain

Question 2

What are the 2 classifications of pain

Answer 2

Nociceptive = tissue (somatic - connective tissue, visceral - organs )
Neuropathic = nerve

Question 3

4 elements to nociceptive pain response

Answer 3

Transduction, transmission, perception, modulation

Question 4

What are the 3 areas related to sensation + perception?

Answer 4

1. Afferent pathways → ascending to brain
   Nociceptors (pain receptors), afferent nerve fibres, spinal cord network - terminate in dorsal horn of spinal cord
2. Central nervous system
   Limbic system, reticular formation, thalamus, hypothalamus, cortex
3. Efferent pathways
   Reticular formation, midbrain, substantia gelatinosa

Question 5

What are nociceptors?

Answer 5

Sensory receptors (nerve endings) activated by noxious stimuli, transmit impulses via C fibre (slow) + A - delta fibres (fast)

Question 6

Describe first element of nociceptive pain response

Answer 6

Transduction -
* response to tissue injury,
* release of chemical mediators (prostaglandins, substance P, histamine, bradykinins, serotonin),
* conversion of energy types,
* generation of action potential

Question 7

Describe second element of nociceptive pain response

Answer 7

Transmission - 3 phases:
* Injury site to spinal cord (A-delta and C fibres)
* Spinal cord to brain stem + thalamus
* thalamus to cortex

Question 8

What is the third element of nociceptive pain response?

Answer 8

Perception - conscious experience of pain
* reticular activating system (RAS)
* somatosensory system
* limbic system
* cortical structures

Question 9

What is the 4th element of pain

Answer 9

Modulation - signals from brain travel down
Release chemical substances - endogenous opioids (encephalins, endorphins), serotonin, noradrenalin

Question 10

A delta fibres

Answer 10

Fast conducting fibres, thinly myelinated
Transmit well localised, sharp pain
Sensitive to mechanical + thermal stimuli
Acute pain

Question 11

C fibres

Answer 11

Unmyelinated
Slow conducting, transmit poorly localised, dull + aching pain
Sensitive to mechanical, thermal chemical stimuli
Persistent pain

Question 12

A beta fibre

Answer 12

Highly myelinated, large diameter
Rapid conducting
Low activation threshold - respond to light touch
Transmit non- noxious stimuli

Question 13

What is the gate theory?

Answer 13

Tactile non-noxious stimuli inhibits pain signal transmission