Emesis Flashcards Preview

Physiology > Emesis > Flashcards

Flashcards in Emesis Deck (8)
Loading flashcards...
1

*Emesis

Triggered by local GI irritants signaling Vomiting Center
Triggered by chemicals or drugs binding to the Chemoreceptor Trigger Zone

2

Stomach sends signal thru ______ to the Vomiting Center

Vagus nerve
- activate motor activity responsible for vomiting

3

CRTZ

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

4

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

5

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*

6

Motion sickness

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

7

Primary (local) GI factors

- chemical irritant
- physical irritant
- distention

8

Stimulation of CRTZ

- drugs
- toxins
- chemical/metabolic byproducts