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Stomach

The Stomach is a very active organ of the body. It is a hollow organ that can be dilated as part of the Digestive System.

It attaches to the lower portion of the Esophagus and the upper portion of the Small Intestines called the Duodenum.

It is located on the central or slightly on the left side of the abdomen. The primary function is the digestion or breakdown of food.

Sphincter muscles are found at the top and bottom of the stomach to keep both the solid and liquid contents in the stomach until the intestines are ready for the next portion of digestion.

The word stomach comes from both Latin and Greek.

Gastro- and gastric both are derived from the Greek word gaster

Sections of the Stomach

Layers of the Stomach

1.)  Mucosa

–  The first layer of tissue
–  Contains cells called epithelium and lamina propria
–  Lamina propria is connective tissue.

2.)  Submucosa

–  This layer lies under the Mucosa
–  It is a Fibrous Connective Tissue
–  The Messiner’s plexus is the next layer of cells

3.)  Muscularis

–  This layer lies under the Submucosa
–  This layer is different in the stomach than other GI organs.
–  There are three layers of smooth muscle rather than just two.

.  Inner Oblique layer
.  Middle Circular layer
.  Outer Longitudinal layer

*** The cells that make up the Auerbach’s plexus if found between the longitudinal and middle circular layers.

This area helps cause peristalsis and mixing in the stomach.

4.)  Serosa

–  The last layer
–  Consists of connective tissue continuous with the Peritoneum

The function of the Stomach

–  The pH of the stomach is essential in the function of the stomach.
–  Proper pH, typically ranges between 1 and 2, allows for the breakdown of food particles.
–  The food (bolus) enters the stomach having already been mashed by the teeth.
–  Several different proteins are developed by several different types of cells found to line the stomach.
–  Pepsinogen or pepsin helps digest protein.
–  Gastric Acid, intrinsic factor, and some hormones are also produced in the stomach.
– Digestion is often interchanged with absorption.
–  In actuality, only a small amount of food is absorbed in the stomach.
–  Water, alcohol, caffeine, aspirin, and a few other compounds are the few.

Hormones Involved in Digestion and Overall Function:

Gastrin

–  This hormone comes from the G-cells in the stomach
–  This hormone is secreted in response to the distension of the Antrum.
–  It doesn’t get released when the pH is less than 4.
–  It also doesn’t get released if another hormone – Somatostatin is present.
–  This hormone increases the secretion of HCL from the Parietal cells.
–  This hormone increases secretion of Pepsinogen from the Chief Cells
–  This hormone increases the motility of the stomach.

Cholecystokinin

–  This hormone is also called CCK
–  It has most of its effect on the Gallbladder
–  It causes the Gallbladder to spasm and contract.
–  This hormone decreases gastric emptying.
–  This hormone increases pancreatic juices that allow for food breakdown.

Secretin

–  This hormone comes from the small intestines
–  This hormone works on the pancreas
–  It can also work to decrease the production of acid in the stomach.

Gastric Inhibitory Peptide

–  This hormone decreases gastric acid in the stomach
–  This hormone also decreases motility

Enteroglucoagon

–  This hormone decreases gastric acid in the stomach
–  This hormone also decreases motility

Disease of the Stomach

– Gastritis
– Gastroenteritis
– Heartburn
– Irritable Bowel Syndrome
– Pyloric Stenosis
– Gastroesophageal Reflux Disease or GERD