Definition

Definitions

Nausea:

Nausea is a subjective, unpleasant sensation typically experienced in the upper abdomen or throat, often described as a feeling of impending vomiting. It is associated with a range of conditions and may occur without actual vomiting.

• Key Characteristics:
  • Often accompanied by autonomic symptoms like pallor, sweating, salivation, or dizziness.
  • May or may not lead to vomiting.

Vomiting:

Vomiting, or emesis, is the forceful expulsion of stomach contents through the mouth. It is a reflex action mediated by the brainstem's vomiting center in response to various stimuli.

• Key Characteristics:
  • Involves a coordinated effort of the gastrointestinal tract and abdominal muscles.
  • Distinguished from regurgitation (passive, effortless return of food or liquid to the mouth).

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Mechanisms Involved

Nausea:

• Often mediated by the brain's higher cortical areas, chemoreceptor trigger zone (CTZ), and vagus nerve activation.

Vomiting:

• Controlled by the vomiting center in the medulla, receiving inputs from:
  1. Chemoreceptor Trigger Zone (CTZ): Sensitive to toxins, drugs, and metabolic disturbances.
  2. Visceral Afferents: From the GI tract due to irritation, distension, or obstruction.
  3. Vestibular System: Balance disturbances (e.g., motion sickness).
  4. Higher Brain Centers: Emotional or sensory triggers.

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Common Causes

Nausea:

• Gastrointestinal: GERD, gastritis, obstruction.
• Neurological: Migraine, motion sickness.
• Systemic: Pregnancy, metabolic disorders.
• Psychogenic: Anxiety, stress.

Vomiting:

• Acute: Infection (gastroenteritis), toxin ingestion.
• Chronic: Gastroparesis, intestinal obstruction, intracranial pressure.

 

 

Nausea and Vomiting

Making the Diagnosis and Management_Adult

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