B2 L21/22- Review of Definitions and Terms

Question 1

Contributors to peripheral sensitisation include ________, _______, ______ or ________.

Answer 1

damaged tissue/cell disruption; inflammation; infection; ischaemia

Question 2

What are 8 key processes in peripheral sensitisation?

Answer 2

1. > Activation & sensitisation of receptors and ion channels
2. A delta and C fibres transduce lower threshold stimuli
3. Silent nociceptors are activated
4. Increased receptive field
5. Neurogenic inflammation
6. Phenotypic switch
7. Sprouting
8. Satellite glial cell activation

Question 3

In the dorsal root ganglion, a variety of processes can occur with inflammatory substances or nerve injury. What are the 3 processes?

Answer 3

1. Phenotypic switch
2. Sprouting
3. Satellite glial cell activation

Question 4

What happens at >Activation & sensitisation of receptors and ion channels?

Answer 4

With release of a range of chemical mediators, degranulation of mast cells to release histamine and increase vessel permeability(‘inflammatory soup’).

Question 5

What is happens when A delta and C fibres transduce lower threshold stimuli?

Answer 5

transmit action potentials

Question 6

What happens when Silent nociceptors are activated?

Answer 6

more C fibres are able to

respond

Question 7

What happens when there is an Increased receptive field?

Answer 7

Stimulus at a larger superficial region is able to threshold with stimulus to a larger superficial region (associated with secondary hyperalgesia and with central changes)

Question 8

What happens during Neurogenic inflammation?

Answer 8

A delta and C fibres also release neuropeptides from their peripheral terminals (chemical feedback) at the site of injury. This can occur with antidromic firing of the neurone.

Question 9

What is the Phenotypic switch?

Answer 9

A beta fibres (normally mechanosensitive for

touch) may switch to releasing substance P at the dorsal horn of the spinal cord – behaving like C fibres.

Question 10

What is sprouting?

Answer 10

neurones advancing into regions that they would not

normally be found e.g. sympathetic nervous system neurones sprouting into dorsal root ganglion

Question 11

What happens during satellite glial cell activation?

Answer 11

Can lower the threshold of neurones or even cause ectopic action potentials.

Question 12

What are 2 processes that occur in central sensitisation?

Answer 12

Wide Dynamic Range neuron fields may change
Wind-up
Long-term potentiation

Question 13

How does Wide Dynamic Range neuron fields change?

Answer 13

as a result of plasticity in excitatory and inhibitory mechanisms, contributing distortion of incoming information that normally codes for body representation and stimulus type.

Summation of repeated C-fibre inputs results in a progressively more depolarised postsynaptic membrane and removal of the magnesium block from the N-methyl-D-aspartate (NMDA) receptor

Question 14

What is wind up?

Answer 14

a train of low frequency C fibre inputs results in a rapid

and progressive increase in action potential output from a dorsal horn cell.

Question 15

What is Long-term potentiation?

Answer 15

Induced by higher frequency stimuli, but

the enhanced response outlasts the conditioning stimulus.

Question 16

What is the key process that occurs in sensory Cortex Plasticity?

Answer 16

Sensory Cortex Remapping: Nerves in the brain are constantly cutting and creating connections, so the sensory homonculus is constantly adapting to experiences. Regions grow and shrink.

Question 17

What is sensory cortex remapping?

Answer 17

Nerves in the brain are constantly cutting and creating
connections, so the sensory homonculus is
constantly adapting to experiences. Regions
grow and shrink.