Pain

Question 1

what is specificity theory?

Answer 1

pain is a distinct sensation, detected and transmitted by specific receptors and pathways distinct ‘pain areas’ of the brain.

Question 2

what is convergence theory?

Answer 2

suggests pain is an integrated and plastic state that is represented by a pattern of convergent somatosensory activity in a network.

Question 3

afferents with free nerve endings detect pain, heat, and cold, and are classified according to:

Answer 3

classified according to activating stimulus, fibre type, and conduction velocity.

Question 4

lightly myelinated A α fibres (fast but slower than proprioceptors) are:

Answer 4

mechano-sensitive,

mechanothermal-sensitive.

Question 5

unmyelinated C fibres (slow) detect:

Answer 5

are polymodal, so detect mechanical, thermal, and chemical stimuli.

Question 6

nociceptors respond specifically to pain (are a subset of afferents with free nerve endings).

Answer 6

b

Question 7

with heat responses, what are two types of fibre activity?

Answer 7

some fibres gradually increase their firing as temperature increases,
whereas some suddenly fire when a threshold (45°C) is reached.

Question 8

fast / first pain is immediate, how can it be mimicked?

Answer 8

mimicked by direct stimulation of A δ fibre nociceptors.

Question 9

slow / second pain is delayed and longer lasting, how can it be mimicked?

Answer 9

mimicked by stimulation of C fibre nociceptors.

Question 10

specific molecular receptors associated with nociceptive nerve endings are activated by heat and what else?

Answer 10

hot chillies.

Question 11

the capsaicin receptor TRPV1 is activated in nociceptive A δ and C fibres at what temperature?

Answer 11

45°C.

Question 12

where is capsaicin also found?

Answer 12

hot chillies.

Question 13

what are the 2 components of central pain pathways?

Answer 13

sensory discriminative - shows signal location, intensity, and type,
affective motivational - shows signal unpleasantness and autonomic activation.

Question 14

the discriminative pathway is the easiest to define, what tract does it involve?

Answer 14

spinothalamic tract.

Question 15

what is hyperalgesia?

Answer 15

increased response / sensitivity to a painful stimulus,

the result of lowered nociceptor threshold.

Question 16

what is allodynia?

Answer 16

painful response to normally innocuous stimulus.

Question 17

what is hyperpathia?

Answer 17

fibre or axonal loss / damage that results in a raising of pain threshold,
when the threshold is exceeded, the subsequent excitability is so great that the pain is excruciating.

Question 18

what is phantom limb pain?

Answer 18

illusion of limb is still present,

indicates that central representation of the body persists in the absence of peripheral input (not passive).

Question 19

what is referred pain?

Answer 19

pain in viscera is perceived as coming from specific locations in the skin according to what organ is affected,
could reflect convergence of visceral afferents onto the same pathways.

Question 20

what is the Melzack and Wall (1965) sensory interaction theory of pain?

Answer 20

pain perception is the result of integration of convergent sensory information.