science

Vomiting

Vomiting is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Vomiting rather than just read about it. In short: Vomiting (scientifically known as emesis, and otherwise known as puking, and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. The vomited contents are known as vomit or vomitus.

Key takeaways

Vomiting belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Vomiting to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Vomiting from memory before moving on to harder problems.

Reference excerpt

Vomiting (scientifically known as emesis, and otherwise known as puking, and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. The vomited contents are known as vomit or vomitus. Vomiting can be the result of ailments such as food poisoning, gastroenteritis, pregnancy, motion sickness, or hangover; or it can be an after effect of diseases such as brain tumors, elevated intracranial pressure, or overexposure to ionizing radiation. The feeling that one is about to vomit is called nausea; it often precedes, but does not always lead to vomiting. Impairment due to alcohol, anesthesia, or other sedatives can cause inhalation of vomit. In severe cases, where dehydration develops, intravenous fluid may be required. Antiemetics are sometimes necessary to suppress nausea and vomiting. Self-induced vomiting can be a component of an eating disorder such as bulimia nervosa, and is itself now classified as an eating disorder on its own, purging disorder.

Complications

Aspiration Vomiting is dangerous if gastric content enters the respiratory tract. Under normal circumstances, the gag reflex and coughing prevent this from occurring; however, these protective reflexes are compromised in persons who are under the influence of certain substances (including alcohol) or even mildly anesthetized. The individual may choke and asphyxiate or develop aspiration pneumonia.

Dehydration and electrolyte imbalance Prolonged and excessive vomiting depletes the body of water (dehydration), and may alter the electrolyte status. Gastric vomiting leads to the loss of acid and chloride directly. Combined with the resulting alkaline tide, this leads to hypochloremic metabolic alkalosis (low chloride levels together with high HCO−3 and CO2 and increased blood pH) and often hypokalemia (potassium depletion). The hypokalemia is an indirect result of the kidney compensating for the loss of acid. With the loss of intake of food the individual may eventually become cachectic. A less frequent occurrence results from a vomiting of intestinal contents, including bile acids and HCO−3.

Mallory–Weiss tear

Repeated or profuse vomiting may cause erosions to the esophagus or small tears in the esophageal mucosa (Mallory–Weiss tear). This may become apparent if fresh red blood is mixed with vomit after several episodes.

Dentistry Recurrent vomiting, such as observed in bulimia nervosa or more rarely anorexia nervosa, may lead to the destruction of the tooth enamel due to the acidity of the vomit. Digestive enzymes can also have a negative effect on oral health, by degrading the tissue of the gums.

Pathophysiology Receptors on the floor of the fourth ventricle of the brain represent a chemoreceptor trigger zone, known as the area postrema, stimulation of which can lead to vomiting. The area postrema is a circumventricular organ and as such lies outside the blood–brain barrier; it can therefore be stimulated by blood-borne drugs that can stimulate vomiting or inhibit it. There are various sources of input to the vomiting center:

The chemoreceptor trigger zone at the base of the fourth ventricle has numerous dopamine D2 receptors, serotonin 5-HT3 receptors, opioid receptors, acetylcholine receptors, and receptors for substance P. Stimulation of different receptors are involved in different pathways leading to emesis, in the final common pathway substance P appears involved. The vestibular system, which sends information to the brain via cranial nerve VIII (vestibulocochlear nerve), plays a major role in motion sickness, and is rich in muscarinic receptors and histamine H1 receptors. The cranial nerve X (vagus nerve) is activated when the pharynx is irritated, leading to a gag reflex. The vagal and enteric nervous system inputs transmit information regarding the state of the gastrointestinal system. Irritation of the GI mucosa by chemotherapy, radiation, distention, or acute infectious gastroenteritis activates the 5-HT3 receptors of these inputs. The CNS mediates vomiting that arises from psychiatric disorders and stress from higher brain centers. The medulla plays an important role for triggering the vomiting act. The vomiting act encompasses three types of outputs initiated by the chemoreceptor trigger zone: Motor, parasympathetic nervous system (PNS), and sympathetic nervous system (SNS). They are as follows:

Increased salivation to protect tooth enamel from stomach acids. (Excessive vomiting leads to dental erosion.) This is part of the PNS output. The body takes a deep breath to avoid aspirating vomit. Retroperistalsis starts from the middle of the small intestine and sweeps up digestive tract contents into the stomach, through the relaxed pyloric sphincter. Intrathoracic pressure lowers (by inspiration against a closed glottis), coupled with an increase in abdominal pressure as the abdominal muscles contract, propels stomach contents into the esophagus as the lower esophageal sphincter relaxes. The stomach itself does not contract in the process of vomiting except for at the angular notch, nor is there any retroperistalsis in the esophagus. Vomiting is ordinarily preceded by retching. Vomiting also initiates an SNS response causing both sweating and increased heart rate.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Vomiting

Start with the simplest possible case. Write down what Vomiting claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Vomiting before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Vomiting ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Vomiting

In research: Vomiting appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Vomiting in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Vomiting is common in secondary-school and first-year university syllabi. It links to neighbouring topics Body fluids, Emetics, Reflexes, so understanding it makes those chapters shorter.
In everyday life: Look for Vomiting outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Vomiting in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Vomiting means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Vomiting out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Vomiting in simple terms?

Why does Vomiting matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Vomiting?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Vomiting.