EDUCATION PERFECT Pain Module 2

Question 1

T/F the sensation of pain is non-discriminative.

Answer 1

True

Question 2

What are the three things that the experience of pain depends on?

Answer 2

1. Sensory coding of stimuli
2. Motivational/affective component (whether brain wants to attend to the input signalling potentially damaging stimuli or is engages with other things)
3. Cognitive/cultural component (When the brain has learnt not to bother with that type of input signalling potentially damaging stimuli)

Question 3

What are pain receptors called?

Answer 3

Nocireceptors/nociceptors

Question 4

T/F The sensory processing of the pain input in the brain cannot be significantly modulated by other brain systems.

Answer 4

False, the pain input can be affected by other brain inputs, hence why sometimes pain is not felt when there is an injury and the brain is distracted.

Question 5

Which sensory nerve fibre classes does pain belong to?

Answer 5

A-delta and C-classes

Question 6

Where do pain sensations originate from?

Answer 6

The specialised endings of nerve fibres, not from special receptor cells.

Question 7

How many basic classes do nociceptors have and what are they called

Answer 7

4
Temperature
Mechanical stimuli
Mechanical and thermal stimuli
Thermal, mechanical and chemical stimuli

Question 8

What are nocireceptors receptive to thermal, chemical and mechanical stimuli called?

Answer 8

Polymodal nocireceptors (AKA wide dynamic range nocireceptors)

Question 9

What are polymodal nociceptors sensitive to?

Answer 9

Polymodal nociceptors are sensitive to thermal, mechanical, and chemical stimuli. They are also known as wide dynamic range nociceptors.

Question 10

Nocireceptors respond to what type of stimuli?

Answer 10

They respond to the same type of stimuli as other cutaneous receptors but only at stimulus levels outside the normal range that can/will harm the organism.

Question 11

What type of charge excites a nociceptor and what ion creates this charge?

Answer 11

They are excited by a positive charge, generally from Na+

Question 12

What is the activation temperature for the TRPV1 channel?

Answer 12

The TRPV1 channel is activated at temperatures above 43°C.

Question 13

Which TRPV channel is involved in pain sensations to hot temperatures and what is its activation temperature?

Answer 13

TRPV2 is involved in pain sensations to hot temperatures and is activated at 52°C.

Question 14

Besides temperature, what other substances can activate the TRPV1 receptor?

Answer 14

The TRPV1 receptor can be activated by capsaicin (found in hot chilies), allyl isothiocyanate (found in mustard and wasabi), and allicin (found in garlic).

Question 15

What sensations can be evoked by consuming capsaicin or allyl isothiocyanate?

Answer 15

Consuming capsaicin or allyl isothiocyanate can evoke hot burning pain sensations.

Question 16

What happens when TRPV1 is activated?

Answer 16

Activation of TRPV1 leads to a painful, burning sensation of scalding heat and pain.

Question 17

What is the consequence of opening the TRPV1 channel?

Answer 17

Opening of the TRPV1 channel leads to the influx of Ca++ ions, the release of Ca++ from internal stores, and subsequent effects on cellular processes.

Question 18

Depolarization

Answer 18

When the membrane potential is positively charged.

Question 19

What can the excess Ca++ released from the activation of TRPV1 cause?

Answer 19

it can be detrimental in the future by breaking down the cytoskeletal proteins and the degradation of mitochondria.

Question 20

Why does some pain start off sharp and is then followed by a slow dull pain?

Answer 20

C-class fibres are unmyelinated and slower than A-delta class nerve fibres hence each would arrive at the CNS at different times.

Question 21

Tissue injuries can cause the following changes at the site of damage.

Answer 21

Allodynia AND Primary hyperalgesia

Question 22

What is Allodynia

Answer 22

when non-noxious/innocuous stimuli are now felt as painful.

Question 23

What is Primary hyperalgesia

Answer 23

when pain stimuli are now felt more intensely.

Question 24

Why do Allodynia and Primary hyperalgesia occur?

Answer 24

changes in the endings of the nociceptor nerve fibres from the damaged area of skin (due to chemicals released from the damaged skin acting on the endings of the nerve fibres).

Question 25

Damage to tissues causes the release of?

Answer 25

inflammatory agents like histamine into the damaged tissue

Question 26

What do the release of inflammatory agents like histamine into the damaged tissue cause?

Answer 26

dilation (swelling) of local blood vessels. A by-product of these effects is fluid leakage out of the blood vessels to cause swelling in the injured tissue.

Question 27

What effect does the fluid accumulation and swelling have on the TRPV1 ion channel?

Answer 27

There is evidence that the stretch caused by local fluid accumulation and swelling can activate the TRPV1 ion channel.