Pain - Physiology to Pharmacology

Question 1

how does affective (emotional) states influence the magnitude of pain experience

Answer 1

presentation of negative pictures caused a decrease in pain tolerance (positive pictures had opposite effect)

Question 2

what are the different descriptors of pain

Answer 2

1-3 = temporal descriptions

1. acute
2. chronic
3. intermittent

4-5 = neurobiological descriptions

4. inflammatory
5. neuropathic

6-7 = spatial descriptions

6. visceral
7. somatic

Question 3

what is physiological pain

Answer 3

pain proportional to intensity of noxious stimulus

protects againts further injury

Question 4

what is pathological pain

Answer 4

pain greater than apparent noxious stimulus

detrimental

ex. phantom limb pain

Question 5

what is the pain pathway

Answer 5

1. nociceptor generates an action potential (transduction)
2. afferent fibre: conducts action potential to CNS (transmission)
3. spinal cord: processing occurs at the level of the dorsal horn (modulation)
4. brain: conscious experience of pain

Question 6

what are the areas in the brain involved in pain perception

Answer 6

1. primary and secondary sensory cortex
2. thalamus
3. midbrain
4. pons
5. brainstem

Question 7

what is nociception

Answer 7

detection of noxious stimuli that actually or potentially cause damage to organism

Question 8

what do nociceptors respond to

Answer 8

1. intense mechanical deformation
2. potentially damaging temperatures
3. noxious chemical stimulation

Question 9

what do C fibres respond to

Answer 9

1. tissue damaging stimuli
2. sharp blow
3. damaging heat
4. chemicals released by mechanically damaged tissue (inflammation)

Question 10

are C fibres myelinated or unmyelinated

Answer 10

unmyelinated

Question 11

are C fibres slow or fast conducting

Answer 11

slow

Question 12

do C fibres respond to dull or sharp pain

Answer 12

dull burning pain

Question 13

are C fibres large or small diameter

Answer 13

small

Question 14

are A fibres large or small diameter

Answer 14

large

Question 15

are A delta fibres myelinated or unmyelinated

Answer 15

unmyelinated

Question 16

are A delta fibres short or fast conducting

Answer 16

fast conducting

Question 17

do A delta fibres respond to dull or sharp pain

Answer 17

sharp pain

Question 18

what are A delta fibres activated by

Answer 18

stimuli that produce strong shearing force in skin (cut, strong blow, tug on a hair)

Question 19

what are the inhibitory influences in the pain perception

Answer 19

1. descending inhibition: descending pathways from periaqueductal grey (PAG) and rostral ventromedial medulla (RVM) contain endogenous opoid pathways –> project to dorsal horn to reduce transmission
2. gate control: activation of AB fibres with tactile, non-noxious stimuli activates inhibitory interneurones in the dorsal horn –> rubbing alleviates pain

Question 20

what is peripheral sensation

Answer 20

inflammatory mediators (PGs, increase nociception activation)

Question 21

what is central sensation

Answer 21

repetitive nociception input enhances transmission at level of dorsal horn (NMDA receptor)

Question 22

what is hyperalgesia

Answer 22

an increased response to a stimulus which is normally painful

primary or secondary

Question 23

what is allodynia

Answer 23

pain due to a stimulus which doesn’t normally provoke pain

Question 24

what occurs during continuing or repeated stimulation of nociceptors

Answer 24

become increasingly reactive (hyperexcitable) with continuing or repeated stimulation

sensation of peripheral nociceptors so that they transmit an amplified signal to the spinal relay centre

chemically mediated

Question 25

what is central sensitization

Answer 25

over activity of second-order neurons in the dorsal horn leads to enhanced pain transmission associated with changes within and between neurons can be transitory or permanent

Question 26

what is analgesia

Answer 26

absence if pain or a reduction in intensiry of pain perceived

Question 27

what are analgesic drugs

Answer 27

local anaesthetics opioids non-steroidal anti-inflammatory drugs alpha 2 adrenoceptor agonists ketamine nitrous oxide

Question 28

what are non-pharmacological methods do reduce pain

Answer 28

nursing care physiotherapy acupuncture transcutaneous electrical nerve stimulation (TENS)

Question 29

where are the sites of drug action

Answer 29

1. brain: sensory cortex (opiods interfere with central conscious perception of pain) 2. spinal cord: dorsal horn (opioids & alpha 2 agonists modulate neurotransmission 3. afferent fibre: local anaesthetics inhibit transmission 4. nociceptor: NSAIDs reduce production of inflammatory mediators

Question 30

what is preventative analgesia

Answer 30

admin of analgesic drugs throughout the perioperative period to prevent or limit the development of sensitization induced by pre-, intra- or post-operative noxious stimulation

Question 31

what is multimodal analgesia

Answer 31

use of a combination of drugs that act at different points in the nociceptive pathway more effective analgesia with fewer adverse effects