Pain Mechanisms - Acute

Question 1

What is pain?

Answer 1

Unpleasant or emotional experience originating in real or potential damaged tissue

Question 2

What are the 3 systems that interact to produce pain?

Answer 2

Sensory
Motivational
Cognitive

Question 3

What is somatogenic pain?

Answer 3

Pain with a cause localised in the body tissue

Question 4

What are the 2 types of somatogenic pain?

Answer 4

Nociceptive pain - stimulation -eg. sunburn
Neuropathic pain - associated with activation of nerves

Question 5

What is psychogenic pain?

Answer 5

Pain for which there is no known physical cause but processing of info in the CNS is disturbed

Question 6

What is an example of phychogenic pain?

Answer 6

Headache
Back pain

Question 7

What is acute pain?

Answer 7

Protective mechanism that alerts the individual that something is causing them harm

Question 8

What is the time scale for acute pain?

Answer 8

Up to 3 months

Question 9

What can be the response to acute pain?
Body changes

Answer 9

Increased HR
Increased respiratory rate
Elevated BP
Pallor or flushing
Dilated pupils

Question 10

What is chronic pain?

Answer 10

Lasts longer than 3 months and extends beyond an acute illness/injury
Cause is unknown

Question 11

What is an example of acute pain?

Answer 11

Skin abrasions
Deep/soft tissue injury
Bone fractures
Superficial burn

Question 12

What is an example of chronic pain?

Answer 12

Inflammatory
Neuropathic
Cancer
Migraine

Question 13

When is pain tolerance decreased?

Answer 13

Repeated exposure
Fatigue, anger, boredom
Sleep deprivation

Question 14

When is pain tolerance increased?

Answer 14

Alcohol consumption
Medication
Faith

Question 15

What is the Gate Theory?

Answer 15

Pain is a balance between info travelling into the spinal cord through small nerve fibres and info travelling though large nerve fibres

Question 16

What does large nerve fibres carry?

Answer 16

Non-nociceptive info

Question 17

What does small nerve fibres carry?

Answer 17

Nociceptive info

Question 18

Describe the production pain via the gate theory

Answer 18

Nociceptive impulses travel through C fibres + A-delta to spinal cord
Create synapses, which function as a gate
Stimulation of larger fibre (A-beta) = close the gate
Decreases stimulation of T cells
Decreases transmission of impulses
Decrease pain perception

Question 19

What are nociceptors?

Answer 19

Free nerve endings
Stimulated by mechanical, chemical + thermal noxae

Question 20

Where are nociceptors localised?

Answer 20

Muscle, skin + viscera

Question 21

What are the different fibre types?

Answer 21

A- beta
A- delta
C

Question 22

Describe C fibres

Answer 22

Smallest
Non-myelinated
Slow transmission
Transmission of dull + diffuse sensations

Question 23

Describe A-delta

Answer 23

Middle
Myelinated
Pain + touch
Middle transmission

Question 24

Describe A-beta

Answer 24

Biggest
Myelinated
Touch
Fastest = feel pain straight away

Question 25

What are the different classes of nociceptors?

Answer 25

TRP - thermal sensitivity TREK - K+ channel with TRPs MDEG - Na+ channel ASICS + DRASICS - H+

Question 26

Describe simple physiology of pain

Answer 26

Nociceptors are free nerve endings Signals are transmitted along afferent nerves (part of peripheral NS) to spinal cord Fibres (C+A) Travel to CNS in spinal cord Then to the brain (thalamus + cortex) = pain perceived

Question 27

Summary of nociceptive transduction

Answer 27

Acute pain = depolarisation of DH neurons Excitation via glutamate (AMPA) + SP (NK1R) receptors

Question 28

What are the 3 neuronal types in the superficial dorsal horn?

Answer 28

Projection neurons Excitatory interneurons Inhibitory interneurons

Question 29

What can each neuron in the SDH receive?

Answer 29

Inputs from A-delta + C fibres

Question 29

What happens from the spinal cord?

Answer 29

2nd afferent neurons transmit impulse from SG to other side of cord Through ventral + lateral horn Impulse carried to spinothalamic tract to the brain

Question 30

Describe the mechanism of the efferent analgesic system

Answer 30

Pain afferents stimulate neurons in periaqueductal gray (PAG) = activation of efferent anti-nociceptive pathway Impulse transmitted to dorsal horn = block transmission of nociceptive signals

Question 31

What is the afferent portion composed of?

Answer 31

Nociceptors Afferent nerve fibres Spinal cord network Terminate in dorsal horn

Question 32

What does the 2nd afferent neuron create?

Answer 32

Spinal part of afferent system

Question 33

What is the portion of CNS involved?

Answer 33

Limbic signal Reticular formation Thalamus Hypothalamus Cortex