Vomiting
Vomiting (or emesis) is the forceful expulsion through the mouth of the contents of one's stomach. It is a mechanism for expelling ingested illness-causing food poisons.
The act may be triggered by stimuli which might indicate the possibility of poisoning, such as motion sickness, or sight of decayed food, or other people vomiting. It can also be induced with an emetic or prevented with an antiemetic. Nausea also may occur after surgery due to the chemicals employed, see Postoperative nausea and vomiting. Vomiting sometimes also occurs in response to an emotional trauma, or after a concussion; in the latter case it can indicate that the head injury is moderate or severe and requires immediate medical attention.
The act may also be triggered intentionally by stimulating the constrictor muscle located in the back of the throat with a finger or other object. It may be triggered voluntarily due to a psychological disorder such as anorexia nervosa or bulimia or to remove a poison in case such has been ingested. (Note: Some poisons should not be vomited as they may be more toxic when inhaled. Always contact a Poison Control center before inducing vomiting.)
The feeling that one is about to vomit is called nausea.
On airplanes and boats, special bags are supplied for sick passengers to vomit into. Alternatively, a special disposable bag is available containing absorbent material that solidifies the vomit quickly, making it convenient and safe to keep (leakproof, puncture resistant, odorless) until there is an opportunity to dispose of it conveniently.
Reflex
Vomiting is co-ordinated in the vomiting center in the medulla. Receptors on the floor of the fourth ventricle of the brain represent a chemoreceptor trigger zone, stimulation of which can lead to vomiting. The chemoreceptor zone lies outside the blood-brain barrier, and can therefore be stimulated by blood-borne drugs which can stimulate vomiting, or inhibit it.
The vomiting act encompassess:
- Increased salivation to protect the enamel of teeth from stomach acids.
- Retroperistalsis, starting from the middle of the small intestine, sweeping up the contents of the digestive tract into the stomach, through the relaxed pyloric sphincter.
- A lowering of intrathoracic pressure (by inspiration against a closed glottis), coupled with an increase in abdominal pressure as the abdominal muscles contract, propels stomach contents into the esophagus without involvement of retroperistalsis. The lower esophageal sphincter relaxes.
- Vomiting is ordinarily preceded by retching. The purpose of retching is to build up the pressure needed to expel the stomach contents from the body. In retching, the body makes movements similar to vomiting. These spasms build up pressure within the chest cavity. When a sufficient amount of pressure has been created, the diaphragm transfers the pressure from the chest to the abdomen, and this pressure then results in actual vomiting.
Content
Examination of the micro-fungal content of vomit can be a means of indentifying illness. Also known as vomitus, vomit contains a high concentration of hydronium and is thus strongly acidic. Bile can enter the vomit during subsequent heaves due to duodenal contraction if the vomiting is severe. The potential physiological complications associated with vomiting are mainly metabolic alkalosis and hypokalemia.
Vomiting in other animals
Whales vomit regularly (every 7 to 10 days) as a means of the ordinary digestive process, to expel inedible things they have swallowed.
The domestic cat is well known for its tendency to vomit, particularly when attempting to dislodge hairballs from its throat or upper gastrointestinal tract. Dogs also vomit often (frequently after eating grass) and are also known for eating their own vomit, a fact even cited in the Bible.
Some adult birds regurgitate food to feed their young, triggered by a feather or a beak of their young. The food can be either incompletely digested or partially predigested, depending on the species. Some bird species may also use regurgitation as a form of defense, vomiting when wounded or molested. When an intruder or a predator comes near a fulmar on its nest, the bird vomits oil up to 3 feet at the enemy.
Some large mammals, including horses, rarely vomit. Many rodents lack the ability to vomit, and that is why mice and rats are easily killed by poisoning.
Related medication
Emetics
An emetic, such as Syrup of Ipecac, is a substance that induces vomiting when administered orally or by injection. An emetic is used medically where a substance (typically poison) has been ingested and must be expelled from the body immediately. Inducing vomiting can remove the substance before it is absorbed into the body.
Antiemetics
An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of some opioid analgesics and chemotherapy directed against cancer.
Euphemisms
As with other physiological processes involving body wastes, vomiting has taboo aspects. This is shown by the large number of colourful euphemisms for vomiting. Slang terms and synonyms for vomiting: Throw up (phrasal verb), puke, barf, heave, hurl, blow chunks, spew, yack, ralph, retch, chuck, chuck up, upchuck, sick up, spit up, bring up, toss cookies, lose your cookies, lose/blow your lunch, boke, chunder, cack, cascade, disgorge, urp, vurp, technicolor yawn, liquid laugh, laugh at the ground, holler New York, call Earl, paint the walls, spray McDonald's.
The experience of vomiting into a toilet has its own synonyms: hug/worship/pray to the porcelain god/goddess, pray to Dionysius, hug the throne, drive/ride the porcelain bus, talk to Ralph on the big white telephone, place a person-to-person call through the sewer system.
See also
External links
- Vomiting FAQ (http://emetophobia.bravepages.com/vomiting.html)
- Cyclical Vomiting Syndrome (http://www.cvsa.org.uk)
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