Harrison's Internal Medicine Chapter 39. Nausea, Vomiting, and Indigestion Nausea, Vomiting, and Indigestion: Introduction Nausea is the subjective feeling of a need to vomit. Vomiting (emesis) is the oral expulsion of gastrointestinal contents resulting from contractions of gut and thoracoabdominal wall musculature. Vomiting is contrasted with regurgitation, the effortless passage of gastric contents into the mouth. Rumination is the repeated regurgitation of stomach contents, which may be rechewed and reswallowed. In contrast to vomiting, these phenomena often exhibit volitional control. Indigestion is a nonspecific term that encompasses a variety of upper abdominal complaints including nausea, vomiting, heartburn, regurgitation, and dyspepsia (the. | Chapter 039. Nausea Vomiting and Indigestion Part 1 Harrison s Internal Medicine Chapter 39. Nausea Vomiting and Indigestion Nausea Vomiting and Indigestion Introduction Nausea is the subjective feeling of a need to vomit. Vomiting emesis is the oral expulsion of gastrointestinal contents resulting from contractions of gut and thoracoabdominal wall musculature. Vomiting is contrasted with regurgitation the effortless passage of gastric contents into the mouth. Rumination is the repeated regurgitation of stomach contents which may be rechewed and reswallowed. In contrast to vomiting these phenomena often exhibit volitional control. Indigestion is a nonspecific term that encompasses a variety of upper abdominal complaints including nausea vomiting heartburn regurgitation and dyspepsia the presence of symptoms thought to originate in the gastroduodenal region . Some individuals with dyspepsia report predominantly epigastric burning gnawing discomfort or pain. Others with dyspepsia experience a constellation of symptoms including postprandial fullness early satiety an inability to complete a meal due to premature fullness bloating eructation belching and anorexia. Nausea and Vomiting Mechanisms Vomiting is coordinated by the brain stem and is effected by neuromuscular responses in the gut pharynx and thoracoabdominal wall. The mechanisms underlying nausea are poorly understood but likely involve the cerebral cortex as nausea requires conscious perception. This is supported by electroencephalographic studies showing activation of temporofrontal cortical regions during nausea. Coordination of Emesis Several brain stem nuclei including the nucleus tractus solitarius dorsal vagal and phrenic nuclei medullary nuclei that regulate respiration and nuclei that control pharyngeal facial and tongue movements coordinate the initiation of emesis. Neurotransmitters involved in this coordination are uncertain however roles for neurokinin NKi serotonin 5-HT3 and vasopressin pathways
