Vomiting is the forceful oral expulsion of gastric content by reflex mechanism
Nausea - Means feeling of desire to vomit
Retching - denotes laboured rhythmic contraction of respiratory and abdominal musculature, which precedes or follows vomiting
Regurgitation - Appearance of previously swallowed food in the mouth without vomiting is due to bringing out oesophageal content.
Vomiting is a complex reflex involving vomiting center which is situated in the medulla, autonomic and somatic neural pathways.
Phases of vomiting
Phase of nausea - Hypersalivation- sweating -retching -Expulsion of gastric content
What is the mechanism of vomiting
- In vomiting there is synchronous contraction of the diaphragm, intercostal muscles and abdominal muscles resulting in increased intra-abdominal pressure.
- This is combined with relaxation of the lower oesophageal sphincter resulting in forcible ejection of gastric content.
- Vomiting without preceding nausea is called projectile vomiting, seen in CNS disorders with intracranial pressure.