Pain

Question 1

Define ‘pain’

Answer 1

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

Question 2

What is nocioceptive pain?

Answer 2

Pain felt following the activation of pain fibres

Question 3

What are nociceptors?

Answer 3

Specialist pain fibres located throughout the body. They respond to tissue damaging stimuli.

Question 4

How is neuropathic pain felt?

Answer 4

If pain nerve fibres are damaged. Normally a long term sensation which is difficult to acutely manage.

Question 5

Define nociception in relation to nociceptive pain:

Answer 5

The conversion of stimuli into nerve impulses by nociceptor pain fibres

Question 6

Define transmission in relation to nociceptive pain:

Answer 6

The movement of nerve impulses along defined pathways to reach the brain.

Question 7

Define perception in relation to nociceptive pain:

Answer 7

The conscious experience of pain which arises through stimulation of higher brain centres

Question 8

Define modulation in relation to nociceptive pain:

Answer 8

An increase or decrease in our perception of pain. Linked to the gate control theory.

Question 9

Which system does pain arise from?

Answer 9

The nervous system.

Question 10

Where are nociceptors located and where do they transmit signals to? (specific Lucy)

Answer 10

In tissues throughout the body. One end of the nociceptor is located in the skin where it detects pain stimuli. The axon of the nociceptor travels within a spinal nerve where it is taken to the spinal cord. The cell body of the nociceptor is located within the dorsal root ganglion which is a swelling in the spinal nerve close to the spinal cord. Pain fibres end in the dorsal horn where they connect with other neurons.

Question 11

Which three types of stimuli activate endings of nociceptors in the skin?

Answer 11

1. temperature- extremes
2. intense pressure
3. chemicals

Question 12

What happens when a nociceptor is stimulated in relation to creating a nerve impulse. What is this process called?

Answer 12

Stimulation causes ion channels on the surface of nociceptors to open allowing sodium and calcium ions to flow through the cell membrane. The movment of these ions into the cell generates a nerve impulse. If the impulse reaches action potential the impulse is passed on. This process is called nociception.

Question 13

An increase in tenderness and pain following injury is known as:

Answer 13

Hyperalgesia

Question 14

Why does hyperalgesia occur?

Answer 14

Prostaglandins are released as a part of the inflammatory response which sensitise the nerve fibres making them more susceptible and responsive to pain stimuli.

Question 15

How are prostaglandins formed? (3 steps)

Answer 15

1. Prostaglandins are formed from arachidonic acid which is a componant of the phospholipid molecules which make up the cell membrane.
2. Phospholipids are converted into arachidonic acid in response to inflammatory stimuli.
3. Arachidonic acid is then converted into prostaglandins by cyclooxygenase enzymes.

Question 16

What is the primary role of prostaglandins?

Answer 16

Prostaglandins bind to receptors on the nerve endings of pain fibres and lower the threshold for activation causing more pain messages to reach the brain.

Question 17

What are the two types of pain fibre present in the skin? What are their functions?

Answer 17

A delta and C fibres.
A delta: fast response to stimuli. Produce an immediate pain sensation.
C fibres: conduct nerve impulse at a slower speed producing a dull aching pain.

Question 18

In the dorsal horn, which two neurotransmitters do A delta and C fibres release? What type of neurotransmitters are they?

Answer 18

Glutamate and substance P which are excitatory neurotransmitters.

Question 19

What happens once glutamate and substance P neurotransmitters are released in the dorsal horn?

Answer 19

They excite relay neurones which then travel in white matter tracts of the spinal cord to reach the brainstem and the midbrain.

Question 20

What is the synapse between A delta and C fibres and relay neurons also known as?

Answer 20

The pain gate

Question 21

What is the white matter carrying relay nerve fibres to the brainstem and the midbrain called?

Answer 21

The spinothalamic tract.

Question 22

What happens when relay nerve fibres reach the brainstem?

Answer 22

The sympathetic nervous system is triggered (fight or flight response)

Question 23

What does perception relate to?

Answer 23

The conscious experience of pain.

Question 24

Where are pain signals sent once they reach the thalamus?

Answer 24

To higher brain centres including the anterior cingulate cortex and the somatosensory cortex. It is through the activation of these higher centres that the perception of pain occurs.

Question 25

Describe the gate control theory of pain:

Answer 25

The transmission of pain impulses can be decreased at the dorsal horn of the spinal cord where there is a ‘gate’ which is able to ‘open’ or ‘close’ limiting the number of pain impulses which reach the brain. The ‘gate’ is ‘opened’ by tissue injury but ‘closed’ by emotional support, massage or analgesia.

Question 26

Which are the two ways the gate control theory suggests that pain can be modulated at the dorsal horn:

Answer 26

1. Counter stimulation- gate is ‘closed’ through massage or stimulation (e.g. TENS machine). Touch fibres travel to the dorsal horn at the same level as pain fibres. Touch fibres reduce the transmission of impulses to relay fibres travelling to the brain.
2. Descending modulation- gate is closed through nerve impulses from the brain (e.g. emotional support). Nerve pathways ending in the dorsal horn can release neurotransmitters including endorphins, serotonin and noradrenaline which help to limit or block transmission.

Question 27

What three main principles must nursing staff look at when assessing pain?

Answer 27

1. The sensory principles: where the pain is located, how it feels, its intensity
2. The emotional principles: how the pain is affecting the individuals mood and emotional state
3. The impact of the pain on the individuals daily lifestyle

Question 28

Nociceptic pain can be further divided into two catagories:

Answer 28

1. Somatic

2. Visceral

Question 29

Describe somatic pain:

Answer 29

Typically occurs within musculoskeletal tissues. E.g. imflammation, trauma, excessive activity. Results in localised pain.

Question 30

Describe visceral pain:

Answer 30

Pain arising from damaged local organs e.g. ‘stomach’ pain. Not well localised or specific.