Emesis

There is such beautiful poetry in science. Consider the following passage by Pamela J. Gunter Smith, (Pam to her friends):

Vomiting is a complex multifaceted event that requires the coordinated response of neural, respiratory, and gastrointestinal centers. It occurs in response to a variety of stimuli, including local irritation and distention of the gut, introduction of various drugs and hormones into the systemic circulation, psychogenic stimuli, and exposure to ionizing radiation. The sequence of events involved in vomiting are as follows. Indications that vomiting is imminent are those of widespread autonomic discharge: hypersalivation, tachypnea, and dilation of the pupils. Events leading to the expulsion of gastric contents are initiated by slow and deep inspiration against a closed glottis. This reduces the intra-thoracic pressure below atmospheric pressure. The abdominal muscles contract strongly, raising the intra-abdominal pressure; the resulting pressure gradient forces the gastric contents into the esophagus. If the hypopharyngeal sphincter is closed, the contents do not enter the mouth but return to the stomach. These events produce the retching that generally precedes vomiting. But if the sphincter is opened (by drawing the larynx and the hyoid bone forward), the gastric contents are expelled into the mouth. Thus, expulsion of the gastric contents is a passive process that does not involve active contractions of the body of the stomach.