Sensory systems (physiology of pain)

Question 1

List some of the different receptor types

Answer 1

nociceptor, mechanoreceptor, chemoreceptor, thermoreceptor, proprioceptor

Question 2

Pacinian and Meissners corpuscles

Answer 2

pacinnian - deep pressure

meissners - light touch

Question 3

What is the receptive field?

Answer 3

area in which the receptor responds to the stimulus

Question 4

What is the adequate stimulus transduced into?

Answer 4

generator potential

Question 5

What does the size of receptor potential tell us?

Answer 5

intensity of stimulus

Question 6

Does amplitude or frequency of AP tell us about intensity of stimulus?

Answer 6

frequency

Question 7

What does the receptive field tell us about the stimulus?

Answer 7

location

Question 8

What 2 things is acuity dependent on?

Answer 8

density of innervation and size of receptive field

Question 9

A beta fibres

Answer 9

large, myelinated - touch, pressure, vibration

Question 10

A delta fibres

Answer 10

small, myelinated, cold fast pain, pressure

Question 11

C fibres

Answer 11

unmyelinated - warmth and slow pain

Question 12

What primary afferent fibres mediate proprioception?

Answer 12

A alpha and A beta

Question 13

Termination of sensory information?

Answer 13

somatosensory cortex of post central gyrus

Question 14

What may convergence underlie?

Answer 14

referred pain

Question 15

2 types of adaption

Answer 15

fast and slow adapting

Question 16

1 positive and 1 negative of convergence

Answer 16

saves on neurons

reduces acuity - increase receptive field size

Question 17

Lateral inhibition positives

Answer 17

gives better definition of boundaries and cleans up sensory information

Question 18

What is perception?

Answer 18

state of mind

Question 19

Explain the gate control theory

Answer 19

mechanoreceptors activate inhibitory interneurons
release endorphins to inhibit transmitter release from nociceptive fibres to close the gate
descending pathways from PAG and NRM

Question 20

NSAIDS - how do they work?

Answer 20

inhibit cyclo-oxygenase which converts arachidonic acid to prostaglandins
work well with pain associated with inflammation

Question 21

What do prostaglandins sensitise nociceptors to?

Answer 21

bradykinin

Question 22

Local anaesthetics - how do they work?

Answer 22

block sodium action potential and hence axonal transmission

Question 23

opiates - how do they work?

Answer 23

reduce nociceptor sensitivity and activate descending pathways to block NT release in dorsal horn