*L05 - Pain Flashcards Preview

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Flashcards in *L05 - Pain Deck (17)
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1
Q

What is pain a combination of?

A

Sensory (discriminative) and emotional (affective) components.

2
Q

What is the international association of pains definition of it?

A

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

3
Q

Which sensory fibres carry touch sensation and which carry pain sensation?

A

Touch is carried by A-beta fibres

Pain is carried by C fibres (dull pain) and A-delta fibres (sharp pain)

4
Q

What moderates pain?

A

Inhibitory interneurones that descend from the brain.

5
Q

What are the two main types of nociceptor and what neurones carry their impulses?

A

Mechanical nociceptor - A-delta fibres carry sharp pain (shearing force)
Polymodal nociceptor - C fibres carry dull pain (heat, chemicals)

6
Q

What is the majority of the dorsal horn made up of?

A

Inhibitory interneurones that have tonic activity to prevent spontaneous activity of pain neurones.

7
Q

What is the difference between skin and visceral innervation?

A

Skin innervation is topographic meaning specific whereas visceral innervation is diffuse.

8
Q

What is the gate theory of pain?

A

That the activity of the afferent neurones must be sufficient to overcome the inhibitory activity of the interneurones. This allows this signal to be transmitted to the brain.

9
Q

Why does rubbing an injury reduce the pain?

A

Activation of the A-beta neurones cause activation of inhibitory interneurones which prevent pain from being transmitted to the brain.

10
Q

In the gate theory of pain what causes the gate to open?

A

With sufficient stimulus there will be enough action potentials on the A-delta neurones to overcome the inhibitory interneurones. A-delta neurones also inhibit the inhibitory neurones.

11
Q

What is the clinical implication of mechanoreceptor activation decreasing pain?

A

That TENS (transcutaneous electrical nerve stimulation) can be used. This activates surface mechanoreceptors which inhibit pain neurones (close the gate).

12
Q

What is the intrinsic analgesic system?

A

The brainstem is rich in opiods that can be released to provide analgesia and close the gate.

13
Q

What is fascilitated pain?

A

Normal physiological pain

14
Q

What can chonic pain lead to?

A

Heightened sensitivity to pain

15
Q

What are the two forms of sensitivity to pain?

A

Central and peripheral sensitivity

16
Q

What is peripheral sensitivity?

A

Increased sensitivity to pain resulting from the inflammatory soup that is created at the site of the injury. This causes primary hyperanalgesia at the site of the injury and secondary (central) hyperanalgesia surrounding it.

17
Q

What is central sensitivity?

A

At synapses the pain signal is amplified due to increased release of neurotransmitters at the synapse. This is beacuse release of substance P causes upregulation of NMDA receptors which when bound by glutamate cause influx of calcium ions. This acts as a second messenger and causes increased neuronal sensitvity.