Vomiting vs Regurgitation
Vomiting and regurgitation are both acts of reflex associated by the layman to the same process of ‘throwing up’. However, as medical symptoms, they give very different meanings. This article will not be focusing in detail on all the possible causes of vomiting and regurgitation, but by looking at the basic mechanism of each process individually, with few examples, it will offer the reader a fundamental understanding of their differences.
Regurgitation is the process, where the content of tracts/vessels is pushed back through the path it initially traveled. This can be blood/lymph back-flowing through the heart and vessels, or the food eaten by an individual pushed up the gastrointestinal tract. The cardiovascular use of the word regurgitation will be first looked at, before going to the gastrointestinal (GI) context.
Valves play a major role in maintaining unidirectional flow of blood in heart and vessels; therefore, defects in these valves can impair their function, causing the backflow of blood; the process is called regurgitation, and the condition is named according to the valve defected. For example, mitral regurgitation is caused by mitral valve defect; likewise, aortic regurgitation and tricuspid regurgitation are caused by defected aortic and tricuspid valves respectively.
As for the GI context of the word regurgitation, in certain individuals, there may be esophageal motility disorders that do not allow all the food to reach the stomach, or there may be weakened contractions/transient relaxations of the sphincter muscles guarding the esophageal openings. Either way, this allows the undigested contents to be pushed up (regurgitated) in small amounts towards the mouth, where they are usually swallowed again. This symptom is usually associated with gastro esophageal reflux disease (GERD) and heartburns.
The act of vomiting (medically known as emesis) on the other hand, is due to triggering of the vomit center in the medulla oblongata region of the brain, which can be caused by a multitude of stimuli. Independent of the stimuli, the response is the same; the active contractions of the abdominal and accessory muscles, opening of esophageal sphincters, reverse peristalsis, and associated cardiovascular and respiratory changes, all in an effort to generate the force needed to flush out and empty the bowel contents through the mouth and nose.This large emptying of bowel contents can cause dehydration and ion imbalances. Also, vomiting is usually preceded by nausea, a feeling of sickness and disgust, not associated with regurgitation.
The vomit center can be triggered by chemo receptors, mechano receptors, splanchnic and vagal nerves present in the stomach, by the motion-sensitive vestibular labyrinthine receptors present in the ears, or by the cerebral cortex and chemoreceptor trigger zones present in the brain. As such, vomiting can be induced by any of the stimuli of these receptors, a common few being abdominal wall distention or obstruction, gastric mucosal irritation, balance disturbance (motion sickness), CNS infection, psychological factors like fear and anxiety, pain, stimulating the cerebral cortex, and certain medications and toxins stimulating the chemoreceptor trigger zone.
Difference between vomiting and regurgitation:
- Vomiting is a process unique to the gastrointestinal system, but regurgitation is a process that can also occur in the blood and lymph vessels.
- Regurgitation in GI tract is due to esophageal mobility disorders or relaxed/weakened esophageal sphincters, whereas vomiting is due to triggering of the vomit center in the medulla oblongata.
- Vomiting is preceded by nausea; regurgitation is not.
- There are many receptors that can be stimulated to trigger the vomit center, but regurgitation cannot be stimulated by such receptors.
- Vomiting involves forceful contractions of the abdominal accessory muscles, but regurgitation involves less forceful contractions and does not involve abdominal and accessory muscle contraction.
- Regurgitation occurs in small amounts, whereas vomiting sometimes includes entire bowel contents. This leads to dehydration and ion imbalance in vomiting, but not in regurgitation.
- Regurgitated material is usually swallowed again; this is not so in vomiting.