Physiology of pain Flashcards
(20 cards)
what is the aim of analgesia?
elimination of pain
haemostasis
how does elimination of pain happen?
comes from the anaesthetic drug, deposition near a sensory nerve to temporarily prevent nerve conduction
where does haemostasis come from?
vasoconstrictor
what affect does haemostasis have on the tissues?
a blanching effect = gives local ischaemia , prolongs activity, reduces the toxicity
what is the order of a nerve cell?
dendrite - cell body - axons
what aspect of an axon contrubutes to conduction?
nodes of ranvier, end feet synapses - chemical transmission
what are the nodes of ranvier the site of?
ionic exchange of pain impulses
what do the nodes of ranvier allow?
jumping of the impulse and increased speed
what can analgesic solution do at the nodes of ranvier?
gain access to nerve fibre and blocks off nerve conduction
where are pain receptors found and what can they be sensitised by?
widely distriputed around the body
prostaglandins
what do chemical transmitters do?
transmit impulses from end feet of one neurone to the dentrites of the next
examples of chemical transmitters?
noradrenaline, serotonin, gamma amino butyric acid, dopamine
conditions causing pain?
inflammation, trauma, ischaemia, necrosis
substances that cause pain?
potassium, sodium, chloride, calcium
what are the 4 phases of physical conduction?
polarisation
depolarisation
action potential
repolarisation
what happens during polarisation?
no pain
potassium in cytoplasm
sodium outwith
what happens during depolarisation?
destruction of polarity
ionic exchange
increase in sodium in the cytoplasm
increase in potassium outwith
what happens during action potential?
change in membrane potential permeability
allows transfer of ions
potassium and sodium exchange
what happens during repolarisation?
sodium potassium pump
reverts ion to polarised state
what happens during resting?
same as polarisation
no pain
quiet resting stage
