All Topics  
Cardia

 

 
   Email Print
   Bookmark   Link
 

 

Cardia
 
 
  Topics Cardia Topic Home

The cardia (also known as Z-line or esophagogastric junction or gastroesophageal junction) is the anatomical
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
 term for the junction orifice of the stomach
Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
 and the esophagus
Esophagus

The esophagus or oesophagus , sometimes known as the gullet, is an Organ in vertebrates which consists of a Muscle tube through which food passes from the pharynx to the stomach....
. At the cardia, the mucosa of the esophagus transitions into gastric mucosa
Gastric mucosa

The gastric mucosa is the mucous membrane layer of the stomach which contains the glands and the gastric pits. In men it is about 1 mm thick and its surface is smooth, soft, and velvety....
.

The cardia is also the site of the lower esophageal sphincter (LES) (also termed cardiac sphincter, gastroesophageal sphincter, and esophageal sphincter).

e is disagreement in the academic anatomy community over whether the cardia is part of the stomach, part of the esophagus or a distinct entity, as described in this article.






Discussion
Ask a question about 'Cardia'
Start a new discussion about 'Cardia'
Answer questions from other users
Full Discussion Forum



Encyclopedia


The cardia (also known as Z-line or esophagogastric junction or gastroesophageal junction) is the anatomical
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
 term for the junction orifice of the stomach
Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
 and the esophagus
Esophagus

The esophagus or oesophagus , sometimes known as the gullet, is an Organ in vertebrates which consists of a Muscle tube through which food passes from the pharynx to the stomach....
. At the cardia, the mucosa of the esophagus transitions into gastric mucosa
Gastric mucosa

The gastric mucosa is the mucous membrane layer of the stomach which contains the glands and the gastric pits. In men it is about 1 mm thick and its surface is smooth, soft, and velvety....
.

The cardia is also the site of the lower esophageal sphincter (LES) (also termed cardiac sphincter, gastroesophageal sphincter, and esophageal sphincter).

Nomenclature and classification

There is disagreement in the academic anatomy community over whether the cardia is part of the stomach, part of the esophagus or a distinct entity, as described in this article. The difference is more than semantic when used in clinical studies and applied to individual patients.

Classical anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
 textbooks, and some other resources, describe the cardia as the first of 4 regions of the stomach. This makes sense histologically
Histology

Histology is the study of the anatomy of cell and tissue of plants and animals. It is performed by examining a thin slice of tissue under a light microscope or electron microscope....
 because the mucosa of the cardia is the same as that of the stomach.

Many recent writings describe it as the esophageal sphincter.

Function

The stomach generates strong acid
Acid

An acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion Activity greater than in pure water, i.e....
s and enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s to aid in food digestion
Digestion

Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be Absorption, for instance, by a blood stream....
. This digestive mixture is called gastric juice
Gastric juice

Gastric juice is a strong acidic liquid, pH 1 to 3 in humans, which is close to being colourless. The hormone gastrin is released into the bloodstream when peptides are detected in the stomach....
. The inner lining of the stomach has several mechanisms to resist the effect of gastric juice on itself, but the mucosa of the esophagus does not. The esophagus is normally protected from these acids by a one-way valve mechanism at its junction with the stomach. This one-way valve is called the esophageal sphincter (ES), and prevents gastric juice from flowing back into the esophagus.

During peristalsis
Peristalsis

Peristalsis is the rhythmic contraction of smooth muscles to propel contents through the digestive tract. The word is derived from New Latin and comes from the Greek language peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein, "to place."...
, the ES allows the food bolus
Bolus (digestion)

In digestion, a bolus is a mass of food that has been Mastication and swallowed. Once a bolus reaches the stomach, digestion begins.* Compare to chyme....
 to pass into the stomach. It prevents chyme
Chyme

Chyme is the semifluid mass of partly digested food expelled by the stomach into the duodenum. In other words, chyme is half digested food. Also known as Chymus, it is the liquid substance found in the stomach before passing through the pyloric valve and entering the duodenum....
, a mixture of bolus, stomach acid, and digestive enzyme
Digestive enzyme

Digestion enzymes are enzymes that break down polymeric macromolecules into their smaller building blocks. Digestive enzymes are found in the digestive tract of animals or humans where they aid in the digestion of food as well as inside cell , especially in their lysosomes....
s, from returning up the esophagus. The ES is aided in the task of keeping the flow of materials in one direction by the diaphragm.

Histology

On histological examination, the junction can be identified by the following transition:

  • nonkeratinized stratified squamous epithelium in the esophagus
    Esophagus

    The esophagus or oesophagus , sometimes known as the gullet, is an Organ in vertebrates which consists of a Muscle tube through which food passes from the pharynx to the stomach....
  • simple columnar epithelium
    Simple columnar epithelium

    A simple columnar epithelium is a columnar epithelium that is uni-layered. In humans, a simple columnar epithelium forms a lining in the uterus and in most organs of the digestive tract including the stomach, small intestine, and large intestine....
     in the stomach
    Stomach

    In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....


However, in Barrett's esophagus
Barrett's esophagus

Barrett's esophagus refers to an abnormal change in the cells of the lower end of the esophagus thought to be caused by damage from chronic acid exposure, or reflux esophagitis....
, the epithelial distinction may vary, so the histological border may not be identical with the functional border.

The cardiac glands
Cardiac glands

The cardiac glands of the stomach secrete primarily mucus. They are few in number and occur close to the cardiac orifice where the esophagus joins the stomach....
 can be seen in this region. They can be distinguished from other stomach glands (fundic glands
Fundic glands

The fundus glands are found in the Body of stomach and Fundus of the stomach.They are simple tubes, two or more of which open into a single duct....
 and pyloric glands
Pyloric glands

The pyloric glands are found in the pyloric portion of the stomach.They consist of two or three short closed tubes opening into a common duct or mouth....
) because the glands are shallow and simple tubular.

Pathology

Deficiencies in the strength or the efficiency of the LES lead to various medical problems involving acid damage on the esophagus.

In achalasia
Achalasia

Achalasia, also known as esophageal achalasia, achalasia cardiae, cardiospasm, and esophageal aperistalsis, is an esophageal motility disorder: The smooth muscle cell layer of the esophagus loses normal peristalsis , and the lower esophageal sphincter fails to relax properly in response to swallowing....
, one of the defects is failure of the LES to relax properly.

Removal

Surgical removal of this area is a called a cardiectomy a term that is also used to describe removal of the heart
Heart

The heart is a muscle organ in all vertebrates responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in annelids, mollusks, and arthropods....
.

Etymology

The word comes from the Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 kardia meaning heart, the cardiac orifice of the stomach.

See also

  • Artificial cardia
    Artificial organ

    An artificial organ is a man-made device that is implanted into, or integrated onto, a human to replace a natural organ , for the purpose of restoring a specific function or a group of related functions so the patient may return to as normal a life as possible....
    , that can be used to fight, between other diseases, esophageal cancer
    Esophageal cancer

    Esophageal cancer is cancer of the esophagus. There are various subtypes, primarily squamous cell cancer and adenocarcinoma. Squamous cell cancer arises from the cells that line the upper part of the esophagus....
    , achalasia
    Achalasia

    Achalasia, also known as esophageal achalasia, achalasia cardiae, cardiospasm, and esophageal aperistalsis, is an esophageal motility disorder: The smooth muscle cell layer of the esophagus loses normal peristalsis , and the lower esophageal sphincter fails to relax properly in response to swallowing....
     and gastroesophageal reflux disease
    Gastroesophageal reflux disease

    Gastroesophageal reflux disease ', Gastro-oesophageal reflux disease ', Gastric reflux disease, or Acid reflux disease is defined as chronic symptoms or mucosal damage produced by the abnormal reflux in...
    .


Additional images