Nausea & Vomiting Flashcards
what is the parasympathetic activation of n&v
increased salivtion, retroperistalsis in duodenum, opening of pyloric sphincter, opening of oesophageal sphincter
sympathetic activation of n&v
sweating, palpitations, racing heart
pressure from skeletal muscles makes pressure forcing you to vomit
emetics
not recommended in humans due to risk of acid aspiration and oesophagitis (corrosion)
use of stomach pump over aspiration if person is unconscious
emetic response
enterochromaffin cells release 5HT onto vagal afferent sensory nerve endings which stimulate 5HT3 receptors, activates nerves and sends signals to higher centres
dorsal vagal complex encompasses the emetic centre, area postrema and vagal afferent terminals
sensory inputs are integrated at the dorsal vagal complex resulting in activatin of abdominal muscles, diaphragm, stomach and oesophagus triggered by emetic response
what stimulates enterochromaffin cells
poisons, irritants and mechanical distention - they stimulate cells in the stomach wall that act like nerves, releasing neurotransmitters which signal nerves in the brain
control stimuli of vomiting
emetic centre in medulla, with input from vagal afferent fibres, cerebral cortex, chemoreceptor trigger zone, vestibular system
chemoreceptor trigger zone
in medulla and signals to the vomit centre
outside BBB
expresses neurotransmitter receptors (5HT3, dopamine, neuropeptide, opioid)
hyoscine
muscarine receptor antagonist
crosses the blood brain barrier and acts on the vestibular system so used in motion sickness
blocks parasympathetic nerve transmission
can cause dry mouth, blurred vision
cinnarizine, promethazine, cyclizine
antihisamines
H1 antagonists, sedatives with some anti-muscurinic properties
limited activity against CTZ vomiting
ondansetron, granisetron
5HT3 antagonist
have action in CTZ and GI tract
useful in post operative vomiting
metoclopramide, prochlorperazine
D2 receptor antagonist
action in CTZ and GI tract
useful in post-operative vomiting
nabilone
cannaboid receptor agonist
used for treatment in chemo n&v
cause drowsiness and dizziness
aprepitant
neurokinin antagonists
target CTZ, emetic centre and GI tract
used in treatment of chemically induced n&v
dexamethasone
corticosteroid
used for chemo nausea as it reduces inflammation and acts on the emetic centre
what is meniere’s disease
inner ear disease
causing vertigo, tinnitus, nausea, hearing loss
H1 antagonist as treatment, including betahistidine
increases blood flow to inner ear which relieves pressure
