Gastrointestinal tract esophagus

The largest use of endoscopic techniques is in the examination of the gastrointestinal tract. Upper intestinal endoscopy is the examination of the esophagus, stomach, and proximal duodenum. Colonoscopy is the examination of the colon, large intestine, and in some cases the distal parts of the small intestine. Cholangiopancreatography is the examination of the biUary tree and pancreas. 

Swallowing. If it is sufficiently irritant or caustic, a swallowed material may cause local effects on the mouth, pharynx, esophagus, and stomach. Additionally, carcinogenic materials may induce tumor formation in the alimentary tract. Also, the gastrointestinal tract is an important route by which toxic materials are absorbed. The sites of absorption and factors regulating absorption have been reviewed (42,43). 

Human GAL1 receptor mRNA has been detected in multiple cell and tissue samples including Bowes melanoma cells, brain, gastrointestinal tract (from esophagus to rectum), heart, prostate, and testes. Rat GAL1 mRNA was detected in olfactory regions, many hypothalamic nuclei (including supraoptic nucleus),... 

In a recent publication, investigators used a specially customized ISO-NOP sensor to monitor, in real time, NO production in the stomach and esophagus of human patients [82], In this method a patient first swallowed two NO electrodes (see Fig. 1.6), which were then withdrawn slowly at 1cm increments every 2 min. The investigators were then able to establish a profile of NO concentration in the upper gastrointestinal tract. 

Inspired air, which is humidified and warmed in the nose, moves rapidly from the nasal cavity to the nasopharynx and into the trachea. Most airborne particles that are inspired are entrapped in the mucus layer of the respiratory region. Subsequently, these particles are removed from the nasal cavity to the nasopharynx and esophagus and eliminated via the gastrointestinal tract through a process known as mucociliary clearance. 

Most substances are not readily absorbed in the mouth or esophagus one of several exceptions is nitroglycerin, which is administered for certain heart disfunctions and absorbed if left in contact with oral tissue. The stomach is the first part of the gastrointestinal tract where substantial absorption and translocation to other parts of the body may take place. The stomach is unique because of its high content of HC1 and consequent low pH (about 1.0). Therefore, some substances that are ionic at pH values near 7 and above are neutral in the stomach and readily traverse the stomach walls. In some cases, absorption is affected by stomach contents other than HC1. These include food particles, gastric mucin, gastric lipase, and pepsin. 

As lewisite is a vesicant, emesis is not recommended in those species that can vomit (dogs, cats, swine, and ferrets). Dilution with milk or water is recommended. Activated charcoal is not recommended as severe irritation/vesication of the esophagus or gastrointestinal tract is likely to occur. Endoscopy can be performed very carefully to determine the extent of injury. Esophageal perforation and/or stricture formation may occur. 

SAFETY PROFILE Poisons by ingestion and inhalation. Powerful irritants. Oxalates are corrosive to tissue and produce local irritation. When ingested they have a caustic effect on the mouth, esophagus, and stomach. The soluble oxalates are readily absorbed from the gastrointestinal tract and can cause severe damage to the kidneys. Oxalates are common components of poisonous plants. When heated to decomposition they emit toxic and irritating fumes. See also OXALIC ACID. 

Irritation or burns of the esophagus or gastrointestinal tract are also possible if caustic or irritant chemicals are ingested. 

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