Physiology: pain

Question 1

what is the definition of pain

Answer 1

an unpleasant sensory and emotional experience, associated with actual tissue damage or described in terms of such damage

Question 2

what are the 4 distinct processes in the physiology of pain

Answer 2

transduction, transmission, modulation, perception

Question 3

describe what the transduction process of pain involves

Answer 3

translation of noxious stimulus into electrical activity at the peripheral nociceptor

Question 4

describe what the transmission process of pain involves

Answer 4

propagation of pain signals as nerve impulses through the nervous system

Question 5

describe what the modulation process of pain involves

Answer 5

modification/hindering of pain transmission in the nervous system
(eg by inhibitory neurotransmitters)

Question 6

describe what the perception process of pain involves

Answer 6

conscious experience of pain, causes physiological and behavioural responses

Question 7

describe what a nociceptor is

Answer 7

specific primary sensory afferent neurones

Question 8

how are nociceptors activated

Answer 8

normally activated by intense noxious stimuli, can be mechanical, thermal or chemical

Question 9

what neurons are first order neurones

Answer 9

nociceptors

Question 10

describe the action of first order neurones

Answer 10

relay info. to second order neurones in the CNS by chemical synaptic transmission

Question 11

what neurotransmitters are involved in nociceptor pathway

Answer 11

glutamate and peptides(eg neurokinin A)

Question 12

where are second order neurones found

Answer 12

ascend spinal cord along anterolateral system(terminate in thalamus)

Question 13

what are the second order neurones mainly comprised of

Answer 13

the spinothalamic tract(STT) and the spinoreticular tract(SRT)

Question 14

describe the role of the spinothalamic tract(STT) in pain

Answer 14

involved in pain perception(location + intensity)

Question 15

describe the role of the spinoreticular tract(STR) in pain

Answer 15

involved in autonomic response to pain, arousal, emotional responses, fear of pain

Question 16

describe the role of third order neurones in pain physiology

Answer 16

relay sensory info. from the thalamus to the primary sensory cortex

Question 17

what are the subtypes of nociceptor

Answer 17

A-gamma fibres and C-fibres

Question 18

describe the myelination of the A-gamma and C-fibres types of nociceptor

Answer 18

A-gamma fibre = thinly myelinated

C-fibre = no myelin

Question 19

describe what stimulus A-gamma and C fibre subtypes of nociceptor respond to

Answer 19

A-gamma fibre = noxious mechanical + thermal

C-fibre = all noxious stimuli

Question 20

describe the type of pain mediated by A-gamma fibre nociceptors

Answer 20

‘first’, or fast, pain

lancinating, stabbing, pricking sensations

Question 21

describe the type of pain mediated by C-fibre nociceptors

Answer 21

‘second’, or slow, pain

burning, throbbing, cramping, aching sensations

Question 22

what different ways is pain classified

Answer 22

mechanism, time course, severity, origin

Question 23

what types of pain are adaptive

Answer 23

nociceptive pain and inflammatory pain

Question 24

what is nociceptive pain stimulated by

Answer 24

intense stimulation of nociceptors by noxious stimuli, mechanical, chemical or thermal

Question 25

what is the function of nociceptive pain

Answer 25

early warning physiological protective system to detect + avoid noxious stimuli(therefore adaptive)

Question 26

what is inflammatory pain activated by

Answer 26

variety mediators released form site of infection, by leucocytes, vascular endothelium and resident mast cells

Question 27

inflammatory pain causes hyperalgesia and allodynia, describe what these are

Answer 27

``` hyperalgesia = heightened pain sensitivity to noxious stimuli allodynia = pain sensitivity to innocuous stimuli ```

Question 28

describe how inflammatory pain is adaptive

Answer 28

promotes repair until healing occurs

Question 29

what is neuropathic pain(pathological) pain caused by

Answer 29

damage to neural tissue

Question 30

what different ways can neuropathic pain be perceived

Answer 30

burning, shooting, numbness, pins and needles | may be less localised

Question 31

what is dysfunctional pain(pathological)

Answer 31

pain with no identifiable damage and no inflammation

Question 32

what different types of pain are pathological, and are they adaptive

Answer 32

neuropathic and dysfunctional are patholgical | maladaptive

Question 33

describe what referred pain is

Answer 33

feeling of pain in the skin distant to the internal organ it originates

Question 34

what types of pain can be felt as referred pain

Answer 34

deep pain or visceral pain

Question 35

what is referred pain caused by

Answer 35

convergence of nociceptive visceral and skin afferents upon same spinothalamic tract neurones

Question 36

what are some sites of referred pain

Answer 36

gall bladder = right shoulder heart = left arm, jaw liver = right base of neck