Stomach and Stomach Ulcers
by Robert Tallitsch, PhD | September 22, 2022
Video introduction to the stomach and ulcers! Share this video with your class!
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Written by: Robert Tallitsch, PhD
A stomach ulcer is the result of gastric (stomach) acid damaging the mucosal lining of the stomach, producing open sores that often bleed and cause stomach pain. Between 6 and 10% of the U.S. adult population is diagnosed with some form of ulcer each year. In this Brain Builder we will discuss the gross and microscopic anatomy of the stomach, followed by a discussion of the symptoms, causes, and possible treatments for stomach ulcers.
Gross Anatomy of the Stomach
The stomach serves three functions:
- Storage of food
- Mixing food and gastric secretions in order to form a semi-liquid substance termed chyme
- Regulation of the passage of chyme into the duodenum of the small intestine
The stomach, which is j-shaped, has two openings. The cardiac orifice is continuous with the esophagus, and the pyloric orifice is continuous with the duodenum of the small intestine. The stomach, which possesses two curvatures (greater and lesser curvatures), is subdivided into four regions: fundus, body, antrum and pylorus. The fundus extends superior to the cardiac orifice on its left side. The body composes the majority of the stomach. The antrum extends from the body of the stomach to the pylorus, which is the tubular portion of the stomach. The pylorus possesses the pyloric sphincter, which is a circular band of smooth muscle that regulates the passage of chyme into the duodenum of the small intestine, as well as preventing the regurgitation of intestinal contents back into the stomach.
The lesser curvature is found on the superior surface of the stomach, extending from the right side of the cardiac orifice to the pylorus. The greater curvature extends from the left side of the pylorus, over the fundus, and inferiorly along the body of the stomach, finally passing inferiorly and then superiorly along the antrum of the stomach, ending at the pylorus.
General Histology of the Stomach
The stomach is arranged into four histological layers. These layers, from superficial to deep, are the:
The epithelium lining the inner surface of the mucosa is composed of simple columnar mucous surface cells.
The lamina propria is deep to the mucosal epithelium, and is composed of loose, irregularly arranged (areolar) connective tissue.
Deep to the lamina propria is the muscularis mucosae, which is composed of a thin layer of circularly arranged smooth muscle and a deeper layer of longitudinally arranged smooth muscle.
The submucosa is composed of dense, irregularly arranged connective tissue. Blood vessels and nerve plexuses are found throughout this layer of connective tissue.
- Muscularis externa
The muscularis externa is composed of three layers of smooth muscle. The inner layer is obliquely arranged, while the middle layer is circularly arranged and the outermost layer is longitudinally arranged.
- Serosa (adventitia)
The serosa is composed of loose, irregularly arranged (areolar) connective tissue.
The histological description of the stomach differs from the gross anatomical description, in that the stomach is subdivided into only three histological regions, in contrast to the four regions described by gross anatomists.
- Cardiac Stomach
The surface epithelium of the cardiac stomach is composed of columnar surface mucous cells. These cells secret mucous which protects the cardiac stomach from any stomach acid that may be regurgitated from the fundic stomach back into the cardiac stomach or esophagus.
- Fundic Stomach
The fundic glands are significantly longer than those of the cardiac and pyloric regions. In addition, three cell types can be distinguished within the fundic glands.
Chief cells are the most numerous cells within the fundic glands. These cells produce an inactive digestive enzyme termed pepsinogen. Pepsinogen becomes activated when it interacts with stomach acid (HCl) or the enzyme pepsin.
Parietal cells produce hydrochloric acid (HCl), also termed stomach acid.
Mucous neck cells produce mucous, which protects the surface epithelium of the stomach from damage by HCl and pepsin.
- Pyloric Stomach
The majority of the cells found in the glands of this histological region of the stomach resemble mucous neck cells. These cells produce a type of mucous that neutralizes HCl and protects the mucosa of the pyloric region of the stomach.
Formation of a Gastric Ulcer
The three most common causes of stomach ulcers are:
- Excessive secretion of gastric acid. This damages the mucosa of the stomach, causing pain and irritation. If the damage extends into the submucosa, bleeding into the stomach lumen occurs and the pain is significantly more intense.
- Over usage of NSAID painkillers. NSAIDs are non-steroidal anti-inflammatory drugs, such as aspirin, ibuprofen and naproxen. These drugs contribute to the formation of ulcers by reducing the effectiveness of the protective characteristics of the mucous produced by the mucous neck cells. As a result, gastric acid damages the stomach’s mucosa, causing pain and irritation. If the damage extends into the submucosa bleeding occurs and the pain is significantly more intense.
- H. pylori bacteria. This bacteria is typically found within the stomach of up to 50% of the people worldwide and, in most individuals, is harmless. However, in some people H. pylori reduces the protective nature of the stomach’s mucous and thereby contributes to the formation of a gastric ulcer.
Difference Between a Gastric Ulcer and a Peptic Ulcer
Often the terms “gastric ulcer” and “peptic ulcer” are incorrectly used as interchangeable terms. The term “gastric” refers to the stomach, while the term “peptic” refers to the digestive system in general. Medically, a gastric ulcer only occurs within the stomach, while a peptic ulcer occurs within the small intestine — typically within the duodenum.
Symptoms of a Gastric Ulcer
Often individuals with a gastric ulcer do not exhibit any specific symptoms. However, the frequent appearance of burning abdominal pain may be an indication of a gastric ulcer, especially if it presents with one or more of the following symptoms:
- Nausea, vomiting, and heartburn — especially after meals
- Pain that typically occurs at night or after eating, persists from minutes to hours, and reoccurs for several weeks at a time
- Bloody or dark stools
Treatment of a Stomach Ulcer and Prevention of Ulcer Reoccurrence
Medicinal treatment of a stomach ulcer is aimed at reducing one or both of the following factors: reduction in the production of stomach acid and the elimination of the bacterial infection caused by H. pylori.
Two types of medications help reduce the production of HCl by the stomach:
- Proton pump inhibitors
- Histamine receptor blockers
Other medications help to coat and protect the stomach’s lining against the effects of stomach acid.
- Over-the-counter medications containing bismuth subsalicylate, such as Pepto-Bismol, help protect the stomach’s lining.
- Prescription medications such as cytoprotective agents help to coat and protect the stomach’s lining
Several antibiotics can be prescribed simultaneously in an effort to eliminate a H. pylori infection within the stomach, which typically cures mid-to-moderate ulcers. Often two antibiotics are prescribed simultaneously with a proton pump inhibitor. This type of stomach ulcer treatment is termed “triple therapy.”
Stomach ulcers can and will heal themselves if the causative factors are eliminated. Then, with an alteration in life-style factors that irritate the stomach, such as reduced smoking and alcohol usage, reduced NSAID usage, and an increased consciousness of one’s diet, the recurrence of stomach ulcers can be either reduced or eliminated.
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