gastrointestinal disorders

• Gastrointestinal disorders


  • Vomiting
  • Diarrhea
  • Constipation
• Vomiting


  The forcible expulsion of the contents of stomach through the esophagus and out of the mouth
• Vomiting


  • It is a reflex that is coordinated by the vomiting center in the medulla oblongata
  • The vomiting center receives inputs from four sources at the periphery

  
• Triggers for the vomiting reflex


  1. Visual, olfactory, and taste receptors transmit signals first to the brain cortex

  2. Vestibular receptors transmit signals first to the cerebellum

  3. Receptors within GIT transmit signals first to the n. tractus solitarius (of the vagus nerve)

  4. Toxins or medications absorbed from GIT to the blood act at the area postrema zone in the medulla

  
• Neural pathways involved in vomiting

  1. Brain cortex (unpleasant smell or sight, fear, pain)

  2. Cerebellum (vestibular stimulations)

  3. Nucleus tractus solitarius (stimulation of pharynx or stomach)

  4. Area postrema chemoreceptor trigger zone (stimulations by toxins and medications present in the blood)

  
• Chemoreceptor trigger zone


  The area postrema can sense changes in the chemical composition of the blood, as the blood-brain barrier is leaky in this area of the brain

  
• Signals from the vomiting center

  1. Signals to the upper GIT organs (tongue, soft palate, pharynx, esophagus, stomach)

  2. Signals to the respiratory and abdominal muscles

  
• Vomitus


  The gastric content expelled during vomiting
• Characteristics of vomitus


  • Hematemesis (presence of blood in vomitus)
  • Yellow or green-colored vomitus (indicates the presence of bile)

  
• Projectile vomiting


  Vomitus is released with a great force, so it is propelled over a short distance
• Causes of projectile vomiting

  • Intestinal obstruction
  • Increased intracranial pressure
  • Poisoning
  • Overeating

  
• Treatment strategies in vomiting

  1. Cessation of vomiting (antiemetic medications)

  2. Rehydration (i.v. fluid replacement)

  3. Correcting electrolyte imbalances

  4. Restoring acid-base balance