Temperature & Nociception

Question 1

Temperature detection

Answer 1

free nerve endings, thermal graduations, specific receptors, TRPM8 and TRPA1 are cold
TRPV1-4 are heat
C- and A- fibres, high intensity mechanical and thermal stim.
dorsal roots -> dorsal horn -> lissauer’s tract -> DH grey matter -> Rexe’s laminae
Spinothalamic and trigeminothalamic

Question 2

Sensitisation

Answer 2

Peripheral: inflams activate nocicep. fibres -> subs. P and CGRP cause histamine release -> decreasing nociceptor activation -> hyperalgesia
Central: increase in DH activity -> subthreshold become active -> enlargement of pain detection fields

Question 3

Wind-up

Answer 3

increase in AP output from DH (repeated pain) -> repeated C-fibre stim = release of glutamate, subs p and CGRP -> activation or NMDA receptors removes Mg2+ block -> increase in post-synp. depol.

Question 4

Inflam vs. Neuropathic

Answer 4

INFLAMM: persisting pain, active inflam. long-term but reversible, protects the wound
NEURO: abnormal and useless, construction of new synpatic contacts via CREB cycle

Question 5

Gate-control

Answer 5

extra stimulus at painful site inhibits the inhibitory interneurons stopping the painful stim being allowed to pass

Question 6

Endogenous opioids

Answer 6

brain-produced analgesia -> descending pathways -> block signals at junction of afferent and 2nd order neuron -> ENKEPHALIN

Question 7

Clinical Signs

Answer 7

increases in: HR, BP, adrenaline in blood, pupil dilation, sweating, aggression
reflex withdrawl
Decreased appetite and activity
Behavioural changes

Question 8

Spinal cord damage at C1-C5

Answer 8

UMN DAMAGE (BOTH)
tetraparesis (UMN)/GP ataxia, spastic tetraplegia
delayed/absent postural reflex
normal muscle mass, hypertonia
normal - hyperreflexia
can affect resp -> death

Question 9

Spinal cord damage at C6-T2

Answer 9

UMN DAMAGE (PELVIC) + LMN DAMAGE (THORACIC)
LMN gait in thoracic, UMN paresis/GP ataxia in pelvic to spastic tetraplegia
delayed to absent postural reflex
reduced tone + atrophy in thoracic, normal to exaggerated tone in pelvic
hyporeflexia in thoracic, hyperreflexia in pelvic
hypalgesia
horner’s syn,
resp effects -> death

Question 10

spinal cord damage at T3-L3

Answer 10

UMN (PELVIC)
UMN paresus/GP ataxia in pelvic to spastic paraplegia, normal thoracic
delayed to absent posturals pelvic
pelvic hypertonia, normal muscle mass
hyperreflexia in pelvic
pelvic: hypalgesia, absent cutan. trunci reflex

Question 11

spinal cord damage at L4-S3

Answer 11

LMN (PELVIC)
flaccid paraparesis and GP ataxia in pelvic to flaccid paraplegia
delayed to absent posturals in pelvic
hypotonia and reduced muscle mass in pelvic
hyporeflexia pelvic
hypalgesia in tail, perineum and anus