Nausea, retching and hypersalivation frequently precede the act of vomiting, which is a highly integrated sequence of involuntary visceral and somatic motor events.
HARRISON’S PRINCIPLES OF INTERNAL MEDICINE, 1994
Vomiting or emesis is a rather dramatic event with a diverse number of causes. It is usually preceded by nausea.
Haematemesis Vomiting of blood. It is presented in CHAPTER 55.
Nausea The unpleasant sickly sensation that can herald the onset of vomiting or can be present without vomiting.
Regurgitation The effortless passage of gastric contents into the mouth in the absence of nausea and without diaphragmatic muscular contractions.
Retching An involuntary act with all the movements of vomiting without the expulsion of gastric contents because the cardiac orifice remains closed.
Rumination The effortless regurgitation of recently ingested food into the mouth, followed by rechewing and reswallowing or spitting out.1
Vomiting The forceful expulsion of gastric contents through a relaxed upper oesophageal sphincter and out of the mouth.