Pain

Question 1

What inflammatory mediators are released if an injury continues to deteriorate?

Answer 1

Prostaglandin
Bradykinin
Nerve growth factors

Question 2

What is the role of prostaglandin?

Answer 2

Controls inflammation and blood flow

Question 3

What is the role of Bradykinin?

Answer 3

Involved in blood-clotting processes

Question 4

What is the role of Nerve growth factors

Answer 4

They make the nerve endings more sensitive.

Released more the injury deteriorates or gets irritated. Nociceptive output will also increase

Question 5

How are free nerve endings activated when tissue is damaged?

Answer 5

Inflammatory mediators are released by tissues.

Histamine and serotonin activate free nerve endings.

Prostaglandin acts as a sensitiser, increasing activation.

The free nerve endings are acting as nociceptors and send these signals to the brain via spinal cord

Question 6

What is the spinothalamic tract?

Answer 6

A pathway in which pain signals to the brain. Carries temperature, pain and crude touch signals.

Question 7

What are the two sides to the spinothalamic tract?

Answer 7

Direct spinothalamic

Indirect spinothalamic

Question 8

What are the characteristics of the direct spinothalamic tract?

Answer 8

Faster Aδ fibres

Contains cortical areas

Better spatial discrimination

Discriminatory sense of pain sensations

Where on the body the damage or danger is happening.

Question 9

What are the characteristics of the indirect spinothalamic tract?

Answer 9

Slower C fibres

Limbic system, hypothalamus, reticular activating system.

Poorer spatial discrimination.

Linked to emotional aspects of pain, understanding salience, memory of previous painful experiences and autonomic responses.

Question 10

What are the two main types of nociceptor fibre?

Answer 10

Aδ Fibre

C Fibre

Question 11

What sensation of pain do you feel from a mechanical Aδ fibre?

Answer 11

Sharp
Pricking
Fast pain

Question 12

What sensation of pain do you feel from a thermal Aδ fibre?

Answer 12

Slow burning
Cold sharp
Pricking

Question 13

What sensation of pain do you feel from a C fibre?

Answer 13

Burning
Cold
Slow, deep pain

Question 14

What is a Aδ fibre?

Answer 14

A myelinated and larger diameter axon, rapid conduction speed.

Question 15

What is a C fibre?

Answer 15

Unmyelinated and smaller diameter axon. Slow conduction speed.

Question 16

Describe the descending inhibitory pathway

Answer 16

Neurons in the brain stem send efferent fibres to the spine. They pass downward in the spine.

The descending modulatory fibres release serotonin and norepinephrine. Releasing powerful endorphins (enkephalins) which reduce the incoming nociceptive signals and therefore reduce central perception of pain.

Question 17

When is glutamate released?

Answer 17

Glutamate is released when the 1st order neuron reaches the synapse and it activates a series of receptors on the polysynaptic cell called AMPA receptors.

Question 18

What is the NDMA receptor?

Answer 18

The more glutamate is being activated, a second receptor is activated - NMDA.

This receptor sensitises the neuron and possible long-term changes to excitability.

Question 19

What is central sensitisation?

Answer 19

Nociceptive signals are pumped to the brain from the 2nd order neuron due to the changes in excitability from the AMPA and NDMA receptor being activated from glutamate production.

Question 20

What is the function of the 1st order neuron in transient sensitisation?

Answer 20

Transient stimulation of the 1st order neuron leads to the activation of AMPA receptors on 2nd order neurons

Question 21

WHEN does central sensitisation happen?

Answer 21

When NMDA receptors are activated on the 2nd order neuron

Question 22

What is the effect of central sensitisation?

Answer 22

Nociceptive signals become more sensitive, a stronger signal is sent to the brain, making the pain experience worse

Question 23

What is peripheral sensation?

Answer 23

Persistent activation of free nerve endings which hence releases substance P (a powerful vasodilator)

Question 24

Why is peripheral sensation a vicious cycle?

Answer 24

If you keep damaging the same damaged tissue, it will hurt more and more and more. Causes a positive feedback loop and hence a vicious cycle.

Question 25

Peripheral compared to central sensitisation.

Answer 25

PS - substance P mediated feedback loop. (presynaptic neurons sensitised) CS - NMDA receptors activated with strong/activated activation. (postsynaptic neurons sensitised)

Question 26

What is nociception vs pain perception?

Answer 26

Nociception is the warning signal, they are not pain. Pain is our brain telling us how important those signals are. The brain generates the pain experience.

Question 27

What psychological states 'open' the pain experience gate?

Answer 27

``` Stress Depression Boredom Worry Lack of activity ```

Question 28

What psychological states 'close' the pain experience gate?

Answer 28

Relaxation Optimism Distraction Positive sense of control

Question 29

What are 4 key psychological factors that can affect pain perception?

Answer 29

1. Attention 2. Experience 3. Expectation 4. Perceived threat

Question 30

What affect does perceptual filtering have on pain perception?

Answer 30

Perceptal filtering of incoming nociceptive information can amplify or attenuate pain perception. (Wiech et al. 2008)

Question 31

What is the Neuromatrix theory of Pain States?

Answer 31

Many different areas in the brain get involved in processing this nociceptive information. What goes on in your brain affects this processing.

Question 32

What factors affect how the neuromatrix of our brain respond to nociceptive signals?

Answer 32

``` Learned responses Attitudes/fears Perception of danger Health beliefs Psychological status ```

Question 33

What are the 3 types of pain?

Answer 33

Somatic (superficial) Somatic (deep) Visceral (deep)

Question 34

What areas of pain is affected (somatic/visceral)

Answer 34

Somatic (superficial = skin) Somatic (deep = deeper skin, muscles, joints) Visceral (deep = organs)

Question 35

What does somatic/visceral pain feel like?

Answer 35

S superficial = sharp fast pain S deep = burning/itching/aching Visceral = dull ache/burning

Question 36

What is the 1st order neuron?

Answer 36

1st order neuron carries the action potentials up the spinal cord

Question 37

What is the 2nd order neuron?

Answer 37

2nd order neuron carries the information up the spine, to the thalamus

Question 38

What is the 3rd order neuron?

Answer 38

3rd order neuron carries the signal further into the CNS from the thalamus to the somatosensory cortex which makes up aware of pain

Question 39

What is hyperalgesia?

Answer 39

Increased sensitivity following tissue injury ``` Primary = localised Secondary = extending to undamaged sites ```

Question 40

What is Allodynia?

Answer 40

Increased sensitivity to non-noxious stimulus