AstraZeneca has delivered this text only version of the course to serve those users who have difficulty accessing the interactive version.
You can access it here: Demo Interactive Version
Further information can be found at: "GORD and Acid-related Disorders" main page
More tutorials at: eCME Homepage
Welcome to "Acid-Related Disorders".
Before beginning, please take a moment to read the course details.
Course Length: Approximately 2 hours. Your
time may vary based on modem speed, prerequisite knowledge and
other factors.
Prerequisites: Anatomy and Physiology of the
Gastrointestinal System.
Date Published: October 2003
Valid Until: October 2006
Acid-related digestive disorders are noted for their high prevalence, varied clinical presentation and high economic cost. This course, “Acid-Related Disorders,” covers the pathophysiology, clinical presentation and various therapeutic options for the acid-related diseases including gastro-oesophageal reflux disease, GORD, peptic ulcer disease and hypersecretory syndromes.
The first section, SYSTEM OVERVIEW, discusses the normal physiology of the stomach and oesophagus, and the mechanism for the production of stomach secretions.
The second section, PATHOPHYSIOLOGY, explores the origin of acid-related diseases, such as GORD and peptic ulcer disease and their effect on other organ systems.
The third section, EPIDEMIOLOGY, reviews the epidemiology of GORD and peptic ulcer disease, and associated risk factors.
The fourth section, PHYSICAL SYMPTOMS, reviews the clinical presentation of GORD and peptic ulcer disease including atypical symptoms
The fifth section, DIAGNOSTIC TESTS, describes methods of assessing the GI tract.
The sixth section, PROGNOSIS, discusses the prognosis of disease, particularly the complications associated with GORD and peptic ulcer disease.
The seventh section, PREVENTION, discusses the pharmacological and non-pharmacological treatment options available for acid-related diseases.
The final section, TREATMENT, discusses surgical treatment options as well as management strategies available for acid-related
Acid-related diseases involve the failure of physiological mechanisms that protect the mucosal lining of the oesophagus, stomach and portions of the small intestine from damage by acid secretions. This section introduces the anatomy and physiology of the oesophagus and stomach.
These are the objectives for this section.
After you finish this section, you should be able to:
Acid-related digestive disorders involve mainly the oesophagus and stomach, and in some cases, the duodenum. This lesson describes the normal physiology of the oesophagus.
The oesophagus is a hollow tube that leads from the throat to the stomach. Although most of this 10-inch long tube is located in the thorax, the lower end of the oesophagus passes through the diaphragm and enters the abdomen at the oesophageal hiatus. Within the abdomen, the oesophagus joins the stomach at the cardiac orifice.
The oesophagus is separated from the pharynx and stomach by valve-like rings of circular muscle tissue known as sphincters. The sphincter that separates the upper end of the oesophagus from the throat is called the upper oesophageal sphincter or UOS, and the sphincter that separates the lower end of the oesophagus from the stomach is known variously as the lower oesophageal sphincter or LOS, the cardiac sphincter, or the gastro-oesophageal sphincter.
Under resting conditions, when there is no food to be delivered from the mouth to the stomach, both sphincters are closed. When food is moved to the back of the mouth, the upper oesophageal sphincter relaxes and the bolus of food is propelled into the oesophagus by the tongue. Food is moved through the oesophagus by successive waves of muscular contraction known as peristalsis. At the lower end of the oesophagus, the combined effect of the peristaltic wave and the weight of the bolus cause the lower oesophageal sphincter to open, allowing the swallowed food to enter the stomach.
The lower oesophageal sphincter is intermittently opened and closed to allow for saliva and air passage.
In addition to regulating the passage of food into the stomach, the lower oesophageal sphincter plays an important role in protecting the oesophagus from the damage that would otherwise result from exposure to the highly acidic gastric fluids of the stomach.
The only secretory product of the oesophageal mucosa is mucus, a slimy, viscous solution made up of water, electrolytes, and a mixture of muco-polysaccharides which acts as a lubricant to provide unimpeded bolus passage, and a protection layer that protects from digestive enzymes and pathogen entry.
In the oesophagus, mucus is produced in great abundance by glandular goblet cells that lie partially buried in the submucosa. Mucus is released when the mechanical pressure exerted by a bolus of food compresses these glandular cells, causing them to secrete their contents onto the surface of the mucosa.
Acid-related digestive disorders involve mainly the oesophagus and stomach, and in some cases, the duodenum. This lesson describes the normal anatomy and physiology of the stomach.
The stomach is a sac-like organ found just under the diaphragm. It is typically “J-shaped”. The inner, concave surface of the stomach is referred to as the lesser curvature, while the outer, convex surface is referred to as the greater curvature.
Anatomically, the stomach is divided into four regions. The small area surrounding the lower oesophageal sphincter is called the cardia. The rounded, dome-like area above the cardia is known as the fundus, and the narrow, distal, funnel-like area at the bottom of the stomach is called the antrum. The area between the fundus and the antrum is known as the corpus, or body, of the stomach. The pyloric sphincter separates the stomach from the duodenum.
The stomach plays an important role in the digestion of food by: secreting gastric acid, and physically by peristaltic contractions.
When the stomach is empty, the mucous membranes lining its walls are highly folded rugae. As the stomach fills, the rugae unfold, exposing the gastric glands and stimulating them to release hydrochloric acid that helps digest food, facilitates the conversion of digestive enzymes to their active form, and kills many bacteria.
The peristaltic contractions of muscles within the stomach wall mixes digestive juices and food to produce a semi-fluid substance known as chyme. Chyme leaves the stomach and enters the small intestine through the pyloric
The mucosa, or mucous membrane, is the layer of epithelial cells that lines the lumen of the stomach and other parts of the digestive tract. Deep indentations within the mucosal surface are composed of mucus neck cells, parietal cells, chief cells, and enteroendocrine cells. These cells produce protective mucus, digestive juices and acids, and hormones that regulate acid secretion.
The mucosa, or mucous membrane, is the layer of epithelial cells that lines the lumen of the stomach and other parts of the digestive tract.
The outermost surface of the gastric mucosa is composed almost entirely of goblet cells. These cells produce the copious amounts of mucus required to protect the stomach walls from being digested by the acidic gastric juices. The thick layer of mucus produced by these cells gives the surface of the stomach a smooth, slippery character. Deep indentations on the mucosal surface, known as gastric pits, house the gastric secretory glands.
Depending on their location in the stomach, gastric glands contain varying numbers of four different types of secretory cells:
Mucus neck cells are found in the upper region of most glands and are responsible for producing mucus, that protect the gland from the corrosive effects of digestive juices.
Parietal cells, also known as oxyntic cells, are responsible for the production of hydrochloric or gastric acid, which is released into the lumen of the stomach.
Chief cells, also known as zymogenic cells, are responsible for the production of pepsinogen, the precursor to a protein-digesting enzyme called pepsin.
Enteroendocrine cells are responsible for the production of gastric hormones involved in the regulation of acid secretion. Gastrin is produced by a family of enteroendocrine cells, known as G cells, and histamine is produced by enterochromaffin-like or ECL cells.
The relative proportion of mucus neck cells, parietal cells, chief cells, and enteroendocrine cells depend on the region of the stomach as shown here. As you might expect, differences in the microstructure of the gastric glands tend to reflect the functional role of each area of the stomach. For example, gastric cells in the cardia and fundus tend to have an unusually high proportion of mucus neck cells, reflecting their greater role in generating the thick layer of mucus that protects the walls of the stomach from acid-related damage. By comparison, glands in the body of the stomach — where most of the chemical breakdown of ingested food occurs — tend to be rich in the parietal cells responsible for the production of gastric acid. Gastric glands in the antrum, which is the last part of the stomach to be emptied when digestion is complete, tend to contain more of the enteroendocrine cells involved in the overall regulation of the digestive