Digestive System Lecture V PDF

Histology of Digestive system Clinical correlations Prof. Dr. Soad A. Treesh. Spring 2024  Gastroesophageal reflux disease Is associated with incompetent barriers at the gastroesophageal junction, caused by a decrease in the lower esophageal sphincter tone or hiatus herni...

Histology of Digestive system Clinical correlations Prof. Dr. Soad A. Treesh. Spring 2024  Gastroesophageal reflux disease Is associated with incompetent barriers at the gastroesophageal junction, caused by a decrease in the lower esophageal sphincter tone or hiatus hernia. Reflux esophagitis (from mild to erosive) develops when the mucosal defenses are not sufficient to protect the esophageal mucosa from the acid, pepsin, and bile, causing symptoms such as heartburn or atypical chest pain. Excessive gastric distention, fatty meals, smoking, and beverages such as tea and coffee (with high xanthine content) also cause relaxation of the lower esophageal sphincter, facilitating the reflux of gastric contents to the esophagus.  Ulceration An ulcer is a disruption of the mucosal integrity that leads to an excavation due to active inflammation. Stress and other psychosomatic factors; The initial ulceration ingested substances such as aspirin, may heal, or it may be nonsteroidal antiinflammatory drugs or further aggravated by ethanol; the hyperosmolality of meals; the local aggressive and some microorganisms (eg, agents, leading to Helicobacter pylori) can disrupt this additional gastric and epithelial layer and lead to ulceration. duodenal ulcers. Atrophic gastritis Pernicious anemia In cases of atrophic The complex of vitamin B12 with intrinsic gastritis, both parietal factor is absorbed by pinocytosis into the and chief cells are cells in the ileum; this explains why a lack much less numerous, of intrinsic factor can lead to vitamin B12 and the gastric juice has deficiency. This condition results in a little or no acid or disorder of the erythrocyte-forming pepsin activity. In mechanism known as pernicious anemia, humans, oxyntic cells usually caused by atrophic gastritis. In a are the site of certain percentage of cases, pernicious production of intrinsic anemia seems to be an autoimmune factor, a glycoprotein disease, because antibodies against that binds avidly to parietal cell proteins are often detected vitamin B12 in the blood of patients with the disease.  Carcinoids Tumors Arise from Enteroendocrine cells, are responsible for the clinical symptoms caused by overproduction of serotonin. Serotonin increases gut motility, but high levels of this hormone/neurotransmitter have been related to mucosal vasoconstriction and damage.  Malabsorption syndrome Deficiencies of disaccharidases enzyme have been described in human diseases characterized by digestive disturbances. Some of the enzymatic deficiencies seem to be of genetic origin. The absorption of nutrients is also greatly hindered in disorders marked by atrophy of the intestinal mucosa caused by infections or nutritional deficiencies, producing the malabsorption syndrome.  Appendicitis Because the appendix is closed ended, it has a very small volume capacity and frequently becomes a site of inflammation (appendicitis). Frequent causes of appendicitis are luminal obstruction (by a fecalith, enlarged lymphoid follicles associated with viral infection, tumors, worms) and ulceration of the mucosa.  Adenocarcinomas Approximately 90–95% of malignant tumors of the digestive system are derived from intestinal or gastric epithelial cells. Malignant tumors of the large bowel are derived almost exclusively from its glandular epithelium (adenocarcinomas). Some proteins such as the carcinoembryonic antigen produced exclusively by malign cells are very important for the diagnosis of cancer.  Hemorrhoids An increase in the size of the vessels of the submucosal venous plexuses of the anal canal results in the formation of hemorrhoids, a condition common in pregnancy and in persons older than 50 years of age. This condition may manifest as painful defecation, the appearance of fresh blood with defecation, and anal itching.