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Vomiting

life science Maturity 11-13 Next article →

Vomiting, also known as emesis, is the forceful expulsion of stomach contents through the mouth or sometimes the nose.

Symptoms-vomiting
Symptoms-vomiting

This biological process is a complex reaction used by the body to respond to various stimuli. It can be a protective response to toxins or a symptom of underlying medical conditions. The substance expelled is referred to as vomit or vomitus. The sensation that precedes this event is called nausea. While nausea often leads to vomiting, it does not always do so. Understanding how the body coordinates this event requires looking at the brain and the digestive system.

The process of vomiting occurs in two distinct stages. The first is the retching phase. During retching, the diaphragm and abdominal muscles undergo coordinated contractions. This phase can feel similar to experiencing violent hiccups, but nothing is actually expelled yet. The second stage is the expulsive phase. In this phase, enormous shifts in the diaphragm and abdomen create intense pressure in the stomach. This pressure is suddenly released when the upper esophageal sphincter relaxes. This allows the gastric contents to be propelled out of the body.

Vomit of partially digested food in a 11 litre container Man-sized glove is shown in photo for scale
Vomit of partially digested food in a 11 litre container Man-sized glove is shown in photo for scale

Control of this reflex begins in the brain. A specific region called the area postrema acts as a chemoreceptor trigger zone. This area is located in the floor of the fourth ventricle. Because the area postrema is a circumventricular organ, it lies outside the blood-brain barrier. This allows blood-borne drugs to stimulate the area and trigger emesis. The vomiting center receives input from several sources. The vestibular system sends signals via the vestibulocochlear nerve, which is common in motion sickness. The vagus nerve is activated when the pharynx is irritated, triggering a gag reflex. The medulla also plays a vital role in initiating the actual vomiting act.

Many different factors can trigger the vomiting reflex. In the digestive tract, causes include gastritis, gastroenteritis, and food poisoning. In infants, pyloric stenosis can cause very forceful projectile vomiting. The sensory system can also trigger the response. Motion sickness occurs when the labyrinthine canals of the ear are overstimulated. The brain can also trigger vomiting due to migraines, concussions, or brain tumors. Even metabolic disturbances, such as hypoglycemia or hypercalcemia, can irritate the system. Psychiatric disorders and stress can also cause the central nervous system to mediate vomiting.

The appearance of vomit can provide important medical clues. The substance is typically malodorous, meaning it has a bad smell. The color of the vomitus can indicate the source of a problem. Yellow or green vomit suggests that bile is flowing from the duodenum into the stomach. If the vomit contains fresh red blood, it may suggest bleeding in the esophagus. If the vomit resembles coffee grounds, it indicates that blood has been partially oxidized by gastric acid. In rare and serious cases, such as an intestinal obstruction, fecal vomiting may occur.

Nationalmuseet - Cophenaghen - brygos vomiting1
Nationalmuseet - Cophenaghen - brygos vomiting1

Frequent or severe vomiting can lead to serious health complications. One major risk is dehydration, which is the depletion of the body's water. Excessive vomiting also causes an electrolyte imbalance. The loss of acid and chloride can lead to hypochloremic metabolic alkalosis. This is a state where blood pH increases and chloride levels drop. Another danger is aspiration, which occurs when vomit enters the respiratory tract. This can lead to choking, asphyxiation, or aspiration pneumonia. This risk is higher for people using alcohol or anesthesia, as these can compromise protective reflexes like coughing.

Repeated vomiting can also cause physical damage to the body. The high acidity of gastric contents can destroy tooth enamel. This is often seen in cases of recurrent vomiting related to bulimia nervosa. Digestive enzymes can also degrade the tissue of the gums. The physical strain of vomiting can cause small tears in the esophageal mucosa, known as a Mallory-Weiss tear. These tears may result in fresh red blood appearing in the vomit.

Sea-sickness bag, Merseyside Maritime Museum
Sea-sickness bag, Merseyside Maritime Museum

While the process is difficult, the body often releases endorphins after the expulsion, which provides a sense of immediate relief.

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🖼️ Images & Media (4)
File:Symptoms-vomiting.jpg
Symptoms-vomiting.jpg
File:Vomit of partially digested food in a 11 litre container Man-sized glove is shown in photo for scale.jpg
Vomit of partially digested food in a 11...
File:Nationalmuseet - Cophenaghen - brygos vomiting1.jpg
Nationalmuseet - Cophenaghen - brygos...
File:Sea-sickness bag, Merseyside Maritime Museum.png
Sea-sickness bag, Merseyside Maritime Museum.png
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