Vomiting Flashcards
define nausea
unpleasant sensation that one may soon vomit
From the latin for ‘ship’
define retching
ABORTIVE REFLEX: MUSCULAR activity of abdomen/ thorax (respiratory muscles), often VOLUNTARY, leading to forced inspiration against closed mouth and glottis without oral discharge of gastric contents (dry heave)
free flow between oesophagus and stomach
define vomiting
involuntary contractions of abdomen, thoracic and GI smooth muscles leading to FORCEFUL expulsion of stomach contents from the mouth
to get rid of toxins
define regurgitation
effortless return of oesophageal or gastric contents in to the mouth NOT associated with nausea or involuntary muscle contractions
define rumination
food that is regurgitated in the postprandial (after eating) period, re-chewed then re-swallowed
used to be kids/ ill adults but increasingly in healthy adults
define gagging
milder form of retching. reflex to protect airway
triggern include tactile (eg fingers to back of throat)
oropharyngeal response eg contraction of soft palate/ spasm in pharynx (no thorax/ abdominal contractions)
examples of gagging responses
contraction of soft palate - spasm in pharynx
4 receptors/ afferents in the vomiting reflex
- GI
- central (area postrema)
- vestibular complex (motion stimuli –> area postrema, nucleus of solitary tract)
- others
explain how GI afferents work
2 receptors: -chemoreceptors (toxins, drugs)
- mechanoreceptors (distention)
- -> activated 5HT receptors –> vagus n carries signal to central pattern generator
where is the area postrema
anterior to 4th ventricle (just inferior/ anterior to cerebellum)
directly superior to nucleus of solitary tract
where does area postrema receive info from 4
- vagus n
- vestibulocochlear n
- blood (emetic signals)
- CSF (emetic signals)
4 examples of ‘other’ afferents in vomiting reflex
- pregnancy (eg morning sickness)
- post-op (esp opiates)
- alcohol excess
- psychological (anorexia, bulemia etc)
what lacks BBB
area postrema
name the vomiting centre
NO VOMITING CENTRE; multiple circuits involved. nucleus of solitary tract and reticular formation are the CENTRAL PATTERN GENERATOR, important in integration
where is the chemoreceptor trigger zone
area postrema
what does the chemoreceptor trigger zone contain 6
receptors for:
- 5HT
- dopamine
- histamine
- acetylcholine
- adrenaline
- morphine
anatomy of stomach (draw)
symptom of failure of lower oesophageal sphincter
heartburn (acid reflux)
efferent pathway of retching
duodenum contracts –> food moves to stomach –> stomach is squeezed by abdominal muscles and diaphragm –> lower oesophageal sphincter relaxes –> food in to oesophagus (does not reach mouth)
efferent pathway of vomiting
PROLONGED abdominal contraction –> relaxed inner hiatal diaphragm –> relaxed oesophagus/ lower oesophageal sphincter –> relaxation of CRICOPHARYNGEUS (upper oesphageal sphincter) –> FORCEFUL EXPULSION
describe the soft palate and glottis during retching/ vomiting
soft palate raised, glottis closed (same as swallowing)
what nerve controls the vomiting reflex
vagus
what may happen if inferior pharyngeal constrictor m (cricopharyngeus) fails to relax?
force of bolus coming up causes oesophageal tears (Mallory Weiss tear) –> blood in vomit
nutritional complications of vomiting
adults: weight loss
kids: failure to gain weight
cutaneous complications of vomiting
petechia, purpura
oropharyngeal complications of vomiting
tooth erosion, sore throat
oesophageal complications of vomiting
- oesophagitis
- oesophageal haematoma
gastro-oesophageal junction complications of vomiting
- mallory weiss tear
- rupture
metabolic complications of vomiting
- changes in balance of electrolytes, pH, water
- metabolic alkalosis (loss of H ions)
unconscious complications of vomiting
aspiration ie choking on sick, bc vomiting reflex is maintained even when unconscious
renal complications of vomiting
- prerenal azotemia
- ATN (acute tubular necrosis)
- hypokalaemic nephropathy
what are emetics agonists of?
5HT (serotonin eg opioids, think of MD)
dopamine (D2)
pharmacology of anti-emetics
5HT/ D2 antagonists
what causes characteristic vomiting sound
glottis not fully closed
