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Flashcards in Emesis Deck (8)
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Triggered by local GI irritants signaling Vomiting Center
Triggered by chemicals or drugs binding to the Chemoreceptor Trigger Zone


Stomach sends signal thru ______ to the Vomiting Center

Vagus nerve
- activate motor activity responsible for vomiting



Located bilaterally on the floor of the 4th ventricle
- "hole" in the blood brain barrier
- stimulated by drugs and toxins: apomorphine, morphine, xylazine (cats), chemotherapeutic drugs


Prelude to vomiting

Antiperistalsis precedes vomiting
- may begin as distal as the ileum
- wave travels backwards at 2-3 cm/sec
- pushes upward along the tract
- gastric and duodenal distention/irritation provides the trigger


Vomiting chain of events

- strong contraction in stomach and duodenum
- partial relaxation of lower esophageal sphincter
- deep intake of breath
- opening of upper esophageal sphincter
- closing of glottis
- lifting of soft palate against posterior nares
- strong downward contraction of esophagus
- simultaneous contraction of abdominal muscles
- complete relaxation of lower esophageal sphincter
*both involuntary and voluntary components*


Motion sickness

Sudden changes in motion stimulates receptors in the vestibular labyrinth
- vestibular receptors --> vestibular nuclei --> cerebellum --> CRTZ --> vomiting center


Primary (local) GI factors

- chemical irritant
- physical irritant
- distention


Stimulation of CRTZ

- drugs
- toxins
- chemical/metabolic byproducts