Pain

Question 1

what is pain?

Answer 1

an unpleasant sensory and emotional experience with actual or potential tissue damage, pain is always subjective

Question 2

what are the five categories for defining pain?

Answer 2

source
severity
quality
extent 
duration

Question 3

what are two reasons we need to experience pain?

Answer 3

first we need pain to signal an actual injury or inflammation and second we need pain to highlight underlying malignancy pain

Question 4

what type of receptors signal pain?

Answer 4

nociceptors and there are many subtypes

Question 5

what are the two types of primary afferent nociceptors?

Answer 5

a-delta fibres (for sharp shooting pain) and c fibres (for dull aching pain)

Question 6

what are the nerve endings of nociceptors like?

Answer 6

they are free, meaning the endings are open to the environment

Question 7

what is primary and second pain?

Answer 7

primary pain sent to NS faster via a-delta fibres and secondary pain takes longer to reach CNS via c fibres

Question 8

what is hyperalgesia?

Answer 8

an abnormally heightened sensitivity to pain which occurs when painful stimuli increases in intensity and the nociceptors increase their firing rates

Question 9

what is allodynia?

Answer 9

when pain is caused by a condition that would not normally elicit pain

Question 10

what are silent nociceptors?

Answer 10

become active following hyperalgesia and allodynia

silent nociceptors form a large reserve pool of pain signalling afferents

Question 11

what is the main central component of pain pathways?

Answer 11

the dorsal horn within the spinal cord

Question 12

what does the dorsal horn act as?

Answer 12

a target for a-delta and c fibres, where these nociceptors then release substance p into the dorsal horn

Question 13

what is substance p?

Answer 13

compound involved in the synaptic transmission of pain signals
an 11 amino acid polypeptide
release requires high levels of firing

Question 14

what is a dorsal horn ‘wind up’?

Answer 14

occurs during conditions of severe persistent damage, and when c fibres under constant fire. the response of dorsal horn then progressivily builds up

Question 15

what is gate control theory?

Answer 15

the theory that rubbing an injury that has just occured will alleviate some of the pain temporarily
this is fue to activation of inhibitory interneurons

Question 16

what are two important pathways with projection neurons?

Answer 16

the spinothalamic pathway and the dorsal column medial lemniscal pathway

Question 17

how can we overcome pain?

Answer 17

via endogenous mechanisms which begin in the midbrain, PAG perisends projection to medulla and Ralphe nucleu and then spinal cord and dorsal horn, such a process initiates release of serotonin and adrenaline

Question 18

what is enkephalon?

Answer 18

an inhibitory internueon that releases enkephalin into the area of opiate receptors, it also reduced transmitters that fire action potentials for pain

Question 19

what are analgesics?

Answer 19

drugs that control pain

Question 20

what are the four categories of analgesics?

Answer 20

non steroidal anti inflammatory drugs (NAIDS)
morphine-like drugs
local anaesthetics
centrally acting non-opiods

Question 21

what is aspirin?

Answer 21

an anti-inflammatory medicine based on salicylyic acid

Question 22

how does aspirin work as an analgesic?

Answer 22

it works by inhbiting the enzyme cyclo-oxygenase (COX) at two stimuli sites: inflammatoy and physiological

Question 23

what are prostaglandins?

Answer 23

involved in inflammation associated with tissue damage and pain
they are produced by the breakdown of arhidonic acid by the COX enzyme

Question 24

what is an example of a CNA acting analgesic?

Answer 24

opium

Question 25

how does opium work?

Answer 25

bind to endogenous opiate receptors designed to dock peptides with opiate like properties, such as endorphins

Question 26

what are four examples of opiod drugs?

Answer 26

diamorphine
codein
pethidine
fentanyl
etorphine

Question 27

how can we treat opiod dependency?

Answer 27

via methadone maintenance treatment

Question 28

what are endorphins?

Answer 28

they are opiod peptides and are widely distributed across the brain

Question 29

what is the future of pain pharmacology in the PNS and the CNS?

Answer 29

cox 2/3 specific inhibitors in the PNS and many targets (including GABAa modulators) in the CNS

Question 30

what are neurosteroids?

Answer 30

rapid non-genomic steroid effects on GABAa receptors to increase excitation

Question 31

how does cannabis work?

Answer 31

binds to two endogenous receptors (CB1 and CB2), inducing analgesic properties

Question 32

what are endocannabinoids?

Answer 32

endogenous lipid based retreograde neurotransmitters that are made on demand and not stored in vesicles

Question 33

what genetic mutations gives rise to an inability to feel pain?

Answer 33

mutation of the FAAH gene

Question 34

what are three considerations for the future treatment of chronic pain?

Answer 34

glycine receptor agonists, propofol, and cone snails