What is the Esophagus?

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(Free-Press-Release.com) January 5, 2005 -- What is the Esophagus?

The esophagus is a hollow tube that transfers food from the throat to the stomach, that is the "food tube". The tube starts just below the "epiglottis", the flap that keeps food from going into our trachea (air pipe) when we swallow. It ends at where it joins with the upper portion of the stomach, called the "cardia". The actual area of coinage is called the "gastroesophageal junction". The esophagus is muscular, to help propel food downward with swallowing. It has a complex array of nerves ("plexus") that work to coordinate the swallowing motion. The upper 2/3 of the esophagus has a inner lining ("mucosa") of a special type of cell, called "squamous" cells, which are also found in the mouth and anal region. These cells resist abrasion and heat and are able to heal quickly if damaged, say by the sharp edges on food. The lower 1/3 of the esophagus has an inner lining of a different type of mucosa called "columnar" cells.

This becomes important for considering the cancers that arise in the esophagus. If the lower portion of the esophagus becomes infiltrated with intestinal-like glands, as it is prone to do with prolonged irritation, then this is called "Barrett's" esophagus and is a risk factor to get cancer, as will be seen.

The esophagus has an outer lining, called the "adventitia", which surrounds the muscular layers and separates the esophagus from other nearby organs. The heart is directly behind the middle esophagus, while the windpipe ("trachea") is directly in front of it. The esophagus is also very close to the liver, lungs, and major blood vessels from the heart ("aorta and venal cava"). The esophagus receives most of it's blood from the aorta and drains it to the liver and venal cava. A system of "drainage channels" runs through the esophagus, between the mucosal and muscular layers. These are called "lymph channels" and act to purify the blood serum, by transporting it to nearby "lymph nodes" (glands) where the serum is filtered. Both the blood supply, and lymph channels and glands, can act as conduits to spread infection or cancer. This spread may be along the length of the esophagus, around it's diameter, to local lymph nodes or organs, or to distant body areas.

When a person has shrinkage ("cirrhosis") of the liver due to excessive alcohol or chronic infections, it places back pressure on the blood draining from the esophagus. This results in swelling of the blood vessels in the lower esophagus, called "varices". These may spontaneously bleed when there is a lot a pressure between the liver and esophagus ("portal hypertension") and is a medical emergency. Other common problems with the esophagus (besides cancer) are "rings" or "webs"-- areas of protrusion into the normally hollow interior ("lumen") of the esophagus where food can get caught. A "stricture" is an area of narrowing of the esophagus, often from scarring from ingested chemicals (i.e. lye). Achalasia is a disease where the nerves in the esophagus don't coordinate swallowing properly, so food gets caught there. An inflammation is "esophagitis", caused by bacteria, virus, or fungi, drugs or radiation.

http://www.canceranswers.com/Esophagus.Cancer.html

what is the esophagus