Vomiting (Emesis)

VOMITING (EMESIS)

  • Vomiting is the spasmodic and forceful ejection of the stomach contents to mouth through dilated oesophagus.
  • Vomiting is very rare in horse due to the presence of well developed and powerful cardiac sphincter and distant position of the stomach from the abdominal walls.
  • In carnivores and omnivore vomiting is common.
  • Herbivores and rodent never vomit.
  • The vomiting centre is located in the lateral reticular formation of the medulla which is stimulated by afferent impulses from pharynx, stomach, duodenum, heart and uterus.
  • In other non-vomiters, the vomiting center may be absent or rudimentary.
  • The cranial nerves 5, 7, 9, 10 and 12 to the upper gastro-intestinal tract and spinal nerves to the diaphragm and abdominal muscles are the efferent nerves involved in the reflex act of vomiting.
  • Act of vomiting
    • It is composed of four phases
      • Oesophageal dilatation
      • Gastric emptying
      • Gastric reflux
      • Oesophageal collapse

Act of vomiting

  • After a deep involuntary inspiration, the glottis and the nasopharynx are closed by elevation of soft palate.
  • Relaxation of oesophagus, gastro-oesophageal junction and the body of the stomach followed  by strong pyloric contraction.
  • The intra-thoracic pressure is increased by the contraction of diaphragm and abdominal muscles.
  • Additional pressure exerted by the contraction of abdominal muscles and the diaphragm, force the stomach contents into mouth through the relaxed oesophagus.
  • Massive antiperistalsis originates from the small intestine which reflux into the stomach.
Last modified: Friday, 30 December 2011, 7:14 AM