Esophagus

2009-01-23T16:40:00.000-08:00

Esophagus
From Wikipedia, the free encyclopedia

The esophagus or oesophagus (British), sometimes known as the gullet, is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. The word esophagus is derived from the Latin oesophagus, which derives from the Greek word oisophagos (οισοφάγος), lit. "what carries and eats". In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. The esophagus passes through a hole in the thoracic diaphragm called the esophageal hiatus. It is usually 25-30 cm long which connects the mouth to the stomach. It is divided into cervical, thoracic, and abdominal parts.

Functions of the esophagus
Food is passed through the esophagus by using the process of peristalsis. Specifically, it connects the pharynx, which is the body cavity that is common to the digestive factory and respiratory system with the stomach, where the second stage of digestion is initiated.

The esophagus is deeply lined with muscle that acts with peristaltic action to move swallowed food down to the stomach. Due to the fact that the esophagus lacks the mucus lining like that of the stomach, it can get irritated by stomach acid that passes the cardiac sphincter.

Functions of the Diaphragm
The diaphragm is crucial for breathing and respiration. During inhalation, the diaphragm contracts, thus enlarging the thoracic cavity (the external intercostal muscles also participate in this enlargement). This reduces intra-thoracic pressure: In other words, enlarging the cavity creates suction that draws air into the lungs. When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity in conjunction with the abdominal muscles, which act as an antagonist paired with the diaphragm's contraction.
It is not responsible for all the breathing related to voice, a common misconception espoused by many teachers but few great singers. One has more control over the abdominals and intercostals than the actual diaphragm, which has relatively few proprioceptive nerve endings. By training proper posture and balance in the rest of the body, the diaphragm naturally strengthens and works in concert with surrounding structures rather than in isolation.
The diaphragm is also involved in non-respiratory functions, helping to expel vomit, feces, and urine from the body by increasing intra-abdominal pressure, and preventing acid reflux by exerting pressure on the esophagus as it passes through the esophageal hiatus.
In veterinary anatomy, the diaphragm is not necessarily crucial; a cow, for instance, can survive fairly asymptomatically with diaphragmatic paralysis as long as no massive aerobic metabolic demands are made of her.

Histology
The layers of the esophagus are as follows:

mucosa

nonkeratinized stratified
squamous epithelium: is rapidly turned over, and serves a protective effect
due to the high volume transit of food, saliva and mucus.

submucosa: Contains the mucous secreting glands (esophageal glands), and connective structures termed papillae.
muscularis externa (or "muscularis propria"): composition varies in different parts of the esophagus, to correspond with the conscious control over swallowing in the upper portions and the autonomic control in the lower portions:

upper third, or superior part: striated muscle
middle third, smooth muscle and striated muscle,
inferior third: predominantly smooth muscle.

adventitia

Gastroesophageal junction
The junction between the esophagus and the stomach (the gastroesophageal junction or GE junction) is not actually considered a valve, although it is sometimes called the cardiac sphincter, cardia or cardias, but is actually more of a stricture.

See also
Esophageal disease

References
^ Physiology at MCG 6/6ch2/s6ch2_30
^ Histology at BU 10801loa

External links

Look up esophagus inWiktionary, the free dictionary.
Virtual Slidebox at Univ. Iowa Slide 449
[hide]
v • d • e Anatomy of torso, digestive system: Gastrointestinal tract
Upper GI
To stomach
Mouth • Pharynx (nasopharynx, oropharynx, hypopharynx) • Esophagus (UES, LES) • Crop
Stomach
rugae – gastric pits – cardia/gland – fundus/gland – pylorus/gland – pyloric antrum – pyloric canal – greater curvature – lesser curvature – angular incisure
Lower GI
Intestine: small
Duodenum (Suspensory muscle, Major duodenal papilla, Minor duodenal papilla) • Duodenojejunal flexure • Jejunum • Ileum • Ileocecal valvecontinuous (intestinal villus, crypts of Lieberkühn, circular folds)
Intestine: large
Vermiform appendix • Cecum • Colon (ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon)continuous (taenia coli, haustra, epiploic appendix)
Termination
Rectum: Houston valve • rectal ampulla • pectinate line
Anal canal: anal valves • anal sinuses • anal columns • Hilton's white line Anus: Sphincter ani internus muscle • Sphincter ani externus muscle
Lymph
GALT: Peyer's patches (M cells)

Retrieved from
"http://en.wikipedia.org/wiki/Esophagus"
Categories: Digestive system Thorax

To read information on other diseases, click on Digestive Diseases Library

2008-02-25T14:41:00.000-08:00

Esophagitis
From Wikipedia, the free encyclopedia

Classification & external resources
ICD-10
K 20.
ICD-9
530.1
MedlinePlus
001153
eMedicine
emerg/175
MeSH
D004941
Esophagitis (or Oesophagitis) is inflammation of the esophagus.

Causes
The most common cause is gastroesophageal reflux disease (Gerd). If caused by GERD, the diseases is also called reflux esophagitis.

Other causes of esophagitis include:

infections (most commonly candida, herpes simplex and cytomegalovirus). These infections are typically seen in immunocompromised people, such as those with HIV.
Food allergies have also been known to cause esophagitis
Chemical injury by alkaline or acid solutions may also cause esophagitis, and is usually seen in children or in adults who attempt suicide.
Physical injury resulting from radiation therapy or by nasogastric tubes may also be responsible.

External links
Esophageal disorders The Merck Manual entry for Esophageal disorders.
Medicine.net
[show]
v • d • e Digestive system - Gastroenterology (primarily K20-K93, 530-579)

For information on anoither disease, click on Digestive Diseases Library.

Digestive Diseases Library