Flashcards in Pathology of the Stomach and Small Bowel Deck (18)
What are the three components of the gastric mucosal barrier?
Pre-epithelial, Epithelial, Sub-epithelial
What is the pre-epithelial layer?
The pre-epithelial layer consists of a mucus coat secreted by mucus cells in the epithelium. It also contains bicarbonate ions and is protective against the hydrogen ions and digestive enzymes within the lumen of the stomach.
Describe the epithelial layer
The epithelial layer contains tight junctions that resist the passage of acid/digestive enzymes into the lining of the stomach. Ion exchangers and cotransporters work to maintain intracellular pH even in the presence of much lower pH in the extracellular environment. Additionally, if there is damage to the epithelium, mucus cells migrate to the area of damage and secrete a mucus cap over the affected area.
What is contained in the sub-epithelium?
The sub-epithelium contains a rich blood supply that provides nutrients, oxygen and anti-inflammatory agents like prostaglandins to the epithelium.
What is acute gastritis?
Acute gastritis is transient gastric mucosal inflammation and results when the mucosal barrier is disrupted. Microscopically, it is characterized by a neutrophilic infiltrate in the mucosa.
Mild forms: surface epithelium is still intact.
Severe forms: erosions of the surface epithelium may lead to hemorrhage (and ulceration if severe enough)
What causes acute gastritis?
Acute gastritis is commonly caused by disruption of the mucosal barrier by
Urease-secreting H. pylori
ingestion of harsh chemicals
What is chronic gastritis?
Chronic gastritis is similar to acute (inflammatory response in mucosal layers) but is usually less severe and more prolonged. Microscopically, chronic gastritis shows lymphocytes and plasma cells in the lamina propria, as well as lymphoid aggregates with germinal centers (adaptive immune responses not seen in acute). Also a variable number of neutrophils are seen in the surface epithelium.
What causes chronic gastritis?
Most commonly, H. pylori is found in the antrum of the stomach. Less commonly, other causes of acute gastritis may lead to chronic: excessive alcohol use, ingestion of irritant chemicals, NSAID use.
What is peptic ulcer disease?
Peptic ulcer disease causes chronic, recurring lesions of the GI mucosa most commonly found in the gastric antrum and the first portion of the duodenum. The ulcers themselves are caused by exposure of the mucosa to acid and digestive enzymes. It is most commonly associated with chronic gastritis resulting from H. pylori infection.
What factors predispose a patient to peptic ulcer disease?
70% of peptic ulcer patients are infected with H. pylori. Other factors that predispose someone to PUD are excessive alcohol use, cigarette smoking, and NSAID use.
What are the five types of diseases in the stomach?
Peptic Ulcer Disease
What is the difference between gastritis and gastropathy?
Gastritis is inflammation and injury
Gastropathy is non-inflammatory injury
What is stress-related Mucosal Disease?
Morphologically, stress-related Mucosal Disease resembles acute gastritis. However, the disease process is mediated by vasoconstriction/ischemia. Erosion and ulceration may be wide spread. Occurs in 75% of critically ill patients.
What is the pathophysiology of H. pylori?
H. pylori is a gram-negative bacillus adapted to gastric environments.
Flagella maneuver through mucus
Adhesion molecules bind to gastric foveolar cells
Acid resistance through abundant urease (NH3)
Elaboration of toxins cause tissue damage
Minimizes and evades immune response
What diseases are associated with H. pylori?
Gastritis with duodenal ulcers
Gastritis with adenocarcinoma
What is the pathophysiology of auto-immune gastritis?
Antibodies to parietal cells and intrinsic factor
+/- Pernicious anemia
Typically Scandinavian and Northern European descent
What disease processes result from auto-immune gastritis?
Lymphocyte and plasma cell infiltrate in the mucosal surface and glandular atrophy.
Also causes intestinal metaplasia