Pain

Question 1

What is the IASP definition of pain?

Answer 1

An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.

Question 2

How is pain passed to the brain?

Answer 2

Receptors sense it and generate AP to pass back into the spine and into brain.

Question 3

Why do we feel pain?

Answer 3

It’s an early warning system, alerts to danger, warning to actual or potential harm.

Question 4

What are the types of pain?

Answer 4

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

Question 5

Cause of superficial somatic pain?

Answer 5

Tissue damage.

Question 6

Cause of deep somatic pain?

Answer 6

Tissue damage.

Question 7

Cause of visceral pain?

Answer 7

Distension, lack of O2, inflammation.

Question 8

Features of superficial somatic pain?

Answer 8

Sharp fast pain, localised and brief, in skin.

Question 9

Features of deep somatic pain?

Answer 9

Burning, itching slow pain, diffuse and long- lasting, in deep layers of skin and muscles.

Question 10

Features of visceral pain?

Answer 10

Dull ache, burning slow pain, can cause nausea, in organs.

Question 11

What is acute pain?

Answer 11

Momentary, lasts for weeks or months (will resolve).

Question 12

What is chronic pain?

Answer 12

3 months or more. Persistent, remains after healing processes, complex lifestyle implications.

Question 13

Why is it not good if we can’t feel pain?

Answer 13

Would have to wear protective gear to stop harming ourselves, pain mechanisms disrupted (producing huge amounts of endogenous NTs).

Question 14

How can some people not feel pain?

Answer 14

Non- functional voltage- gated sodium channels, can’t generate APs as these are dependent on sodium channels.
Therefore, can’t send these back to the brain (no nociception).

Question 15

What is nociception?

Answer 15

The neural process of encoding noxious stimuli (dangerous stimuli). It is a different phenomenon to pain perception (free nerve endings activated and carried to CNS through spinal tracts).

Question 16

What is the meaning of polymodal?

Answer 16

The ability to respond to many inflammatory mediators.

Question 17

What is the process of nociception reaching the CNS?

Answer 17

There are lots of sensory proteins in the free nerve ending (histamine and bradykinin) and if the free nerve ending is activated, it senses damage and depolarise to generate an AP.

Question 18

Which inflammatory mediators are the activators?

Answer 18

K+, H+, histamine and serotonin (from mast cells).

Question 19

Which inflammatory mediators are sensitisation?

Answer 19

prostaglandin (vasodilation), bradykinin (coagulation, make nerve endings more sensitive), nerve growth factors.

Question 20

What is neurogenic inflammation?

Answer 20

Releasing from nerve endings, add to the inflammation response.

Question 21

What is the purpose of Substance P?

Answer 21

Activates mast cells to release more histamine (very powerful vasodilator)

Question 22

What is peripheral sensitisation?

Answer 22

Caused by the release of Substance P (if you keep damaging the same area, becomes more and more sensitive)- positive feedback loop.

Question 23

How does the nociceptive info get into the spine?

Answer 23

Through the spinothalemic pathway (C- fibres and Ad fibres are 1st order and are passed to 2nd order in spine).

Question 24

What kind of receptor is a C-fibre?

Answer 24

Polymodal, hot and burning sensation (slow pain).

Question 25

What kind of receptor is A delta fibres?

Answer 25

Mechanical and thermal, mechanothermal. (sharp prickling fast pain).

Question 26

What is central sensitisation?

Answer 26

Where a 1st order neuron (C fibre) at a pre-synpatic cell releases glutamate which is sensed by the 2nd order neurons.

Question 27

What are the 2 types of glutamate receptor?

Answer 27

AMPA and NMDA (NMDA if there is lots of glutamate released, otherwise inactive).

Question 28

What enters the cell if glutamate binds to AMPA receptor?

Answer 28

Na+ enters (allows to generate APs).

Question 29

What enters the cell if glutamate binds to NMDA receptor (strong stimulation)?

Answer 29

CA2+ (this sensitises the post synaptic cell).

Question 30

What is the difference between peripheral and central sensitisation?

Answer 30

Peripheral is where the pre synaptic cell is sensitised through the release of Substance P. Central is where the post synaptic cell is sensitised through Ca2+ entering cell from NMDA.

Question 31

What type of nerve fibre is used with the indirect spinothalemic pathway?

Answer 31

C- fibre (slower)- limbic system, hypothalamus.

Question 32

What type of nerve fibres is used with the direct spinothalemic pathway?

Answer 32

Faster A delta fibres- myelinated to carry the AP very fast. To cortical areas and for better spatial discrimination.

Question 33

What is referred pain?

Answer 33

This is where you feel pain in other organs (stress and nociceptive signals in places you wouldn't expect). For example, you can feel an MI in your arm.

Question 34

What is the reason for referred pain?

Answer 34

When an embryo, the places were originally really close together and as the areas develop, they move further apart but still send sensory info to the same part of the brain.

Question 35

What is pain modulation?

Answer 35

-Changing the volume of signals coming through -Changing salience- perception of those signals.

Question 36

What is the pain gate model?

Answer 36

Both of the 1st order neurons (AB and C) are activated at the same time, AB activates the inhibitory interneuron which reduces the activation and release of GABA. Therefore, this closes down the 2nd order neuron activity so feel less pain (less nociceptive signals get to the brain).

Question 37

How can the pain gate model be used for pain modulation?

Answer 37

'rubbing it better'. Article that shows gentle stroking babies provides pain relief (C fibres are active rated by light stroking).

Question 38

What are factors that open the pain gate?

Answer 38

-stress, tension, depression, worry, boredom etc.

Question 39

What are factors that close the pain gate?

Answer 39

relaxation, optimism, happiness, distraction.

Question 40

What is the difference between nociception and pain perception?

Answer 40

Nociception is the signals coming into the brain and pain perception is interpreting these signals (different depending on the situation).

Question 41

What are the 2 descending pathways?

Answer 41

serotonergic (release serotonin) and noradrenergic (release adrenaline). These are both inhibitory NTs.

Question 42

What is the process of these inhibitory NTs for the pain gate?

Answer 42

These inhibitory NTs are released onto the interneurons and they release endorphins onto the chemical synapse between the 1st and 2nd order neurons. This closes the pain gate.

Question 43

What is the central neuropathic pain (when system goes wrong)?

Answer 43

Things such as stroke, spinal cord injury. Central sensitisation can become pathological as it disrupts the communication between different parts of the brain (inappropriately perceiving pain).

Question 44

What is the peripheral neuropathic pain?

Answer 44

Physical trauma to the nerve (sends inappropriate signals to the brain to perceive pain).

Question 45

What happens when a nerve root is crushed?

Answer 45

Stop producing neutrotrophins and start producing nerve growth factors (inflammation response).

Question 46

What is the impact of a herniated disc?

Answer 46

This is where a nerve root is pressurised and so feel pain.

Question 47

What is hyperalgesia?

Answer 47

This is increased sensitivity (tissue injury and the area becoming more sensitive). -Caused by peripheral sensitisation and its an exaggerated response to painful stimuli.

Question 48

What is allodynia?

Answer 48

This is increased sensitivity to non- noxious (non painful) stimuli. Central mechanism and switch inhibitory to excitatory (touching with a feather causes pain.

Question 49

What is the autonomic response to acute pain?

Answer 49

Fight or flight response.

Question 50

What is the autonomic response to chronic pain?

Answer 50

Often none.

Question 51

What is psychological component of acute pain?

Answer 51

associated anxiety.

Question 52

What is psychological component of chronic pain?

Answer 52

Increased irritability, depression, sleep issues, appetite changes.