Control CS9 pain and somatosensory disorders

Question 1

What are the 5 main receptors in the skin?

Answer 1

Meissener corpuscle
Pacinian capsule
Ruffini’s corpuscles
Merkel’s discs
Free nerve ending

Question 2

Which skin receptor is involved in sensing pain?

Answer 2

Free nerve endings

Question 3

Which afferent fibres are involved in relaying pain sensation?

Answer 3

A delta and C axon fibres

Question 4

What pain is communicated via A-delta fibres?

Answer 4

Fast onset, short lasting, sharp or prickling pain that is easily localised and usually sensed via mechanical or thermal nociceptors

Question 5

What pain is communicated by C fibres?

Answer 5

Slow onset, persistent dull ache or burining pain which tends to be poorly localised and sensed via polymodal nociceptors

Question 6

What channels are most commonly related to congenital insensitivity to pain?

Answer 6

Voltage gated sodium channels Nav1.7, Nav1.8 and Nav1.9 - deficit/mutation to Nav1.7 most commonly

Question 7

What is allodynia?

Answer 7

When things that’s shouldn’t be painful become painful e.g. water in the shower becomes painful when skin is sunburned

Question 8

What is hyperalagesia?

Answer 8

When painful stimulants become more painful than they were before

Question 9

What are the 4 types of inflammatory mediators?

Answer 9

1. Act directly to activate Logan-gated ion channels e.g. ATP and H+
2. Act via activation of G-protein-coupled receptors e.g. prostaglandins and histamines
3. Act via activation of receptor tyrosine kinases e.g. NGF and BDNF
4. Gasotransmitters e.g. CO and NO

Question 10

What are 3 signalling cascades of inflammatory nociception?

Answer 10

1. Activation/sensitisation of sensory channels
2. Modulation do ion channels through intracellular signalling
3. Modulation of gene expression

Question 11

What is the gate controlled theory of pain?

Answer 11

Pain is suppressed by mechanoreceptors and descending inhibitory pathways usually under stress e.g. in a war zone

Question 12

What is central sensitisation of pain?

Answer 12

The process through which a state of hyperexcitability is established in the CNS leading to enhances processing of nociceptive messages causing sustained pain states

Question 13

Where can pain originate?

Answer 13

Peripherally e.g. from a cut or joint pain or centrally e.g. a migraine