Transcript Document
Achalasia • Achalasia is a condition in which the lower esophageal sphincter fails to relax during swallowing • Food swallowed into the esophagus then fails to pass from the esophagus into the stomach • Damage in the neural network of the myenteric plexus in the lower two thirds of the esophagus. • The musculature of the lower esophagus remains spastically contracted and the myenteric plexus has lost its ability to transmit a signal to cause receptive relaxation of the gastroesophageal sphincter as food approaches this sphincter during swallowing • Stretching the lower end of the esophagus by means of a balloon inflated on the end of a swallowed esophageal tube • Antispasmotic drugs (drugs that relax smooth muscle) can also be helpful. Gastritis (Inflammation of the Gastric mucosa) • The inflammation may be • Superficial • Deep • • • • It can be due to Irritant substances in the ingested food Stomach’s own peptic secretions Bacterial infection Gastric Atrophy • In many people who have chronic gastritis the mucosa gradually becomes more and more atrophic until little or no gastric gland digestive secretion remains • Some develop autoimmunity against the gastric mucosa leading eventually to gastric atrophy • Loss of the stomach secretions in gastric atrophy leads to achlorhydria and occasionally to pernicious anemia. Achlorhydria • Stomach fails to secrete hydrochloric acid Pernicious Anemia in Gastric Atrophy • Normal gastric secretions contain a glycoprotein called intrinsic factor secreted by the same parietal cells that secrete hydrochloric acid. • Intrinsic factor must be present for adequate absorption of vitamin B from the ileum 12 Peptic Ulcer • A peptic ulcer is an excoriated area of stomach or intestinal mucosa caused principally by the digestive action of gastric juice or upper small intestinal secretions Marginal Ulcer • Type of peptic ulcer formed at the site wherever a surgical opening such as a gastrojejunostomy has been made between the stomach and the jejunum of the small intestine • The usual cause of peptic ulceration is an imbalance between the rate of secretion of gastric juice and the degree of protection • Bacterial Infection by Helicobacter pylori Breaks Down the Gastroduodenal Mucosal Barrier • psychic disturbances may cause peptic ulceration. • Other factors that predispose to ulcers include (1)smoking presumably because of increased nervous stimulation of the stomach secretory glands; (2) Alcohol because it tends to break down the mucosal barrier (3) aspirin and other non-steroidal anti-inflammatory drugs that also have a strong tendency for breaking down this barrier • Use of antibiotics along with other agents to kill infectious bacteria • Administration of an acid-suppressant drugs Diarrhea • Diarrhea results from rapid movement of fecal matter through the large intestine • Infectious Diarrhea • Psychogenic Diarrhea • Ulcerative colitis Vomiting • Vomiting is the means by which the upper gastrointestinal tract rids itself of its contents when almost any part of the upper tract becomes excessively irritated, overdistended or even over excitable • Excessive distention or irritation of the duodenum provides a strong stimulus for vomiting • The sensory signals that initiate vomiting originate mainly from the pharynx, esophagus, stomach and upper portions of the small intestines. • These sensory signals are transmitted by both vagal and sympathetic afferent nerve fibers to widely distributed nuclei in the brain stem that all together are called the vomiting center • Motor impulses that cause the actual vomiting are transmitted from the vomiting center by way of the 5th, 7th, 9th, 10th, 12th cranial nerves to the upper gastrointestinal tract, through vagal and sympathetic nerves to the lower tract and through spinal nerves to the diaphragm and abdominal muscles. • Antiperistalsis begins to occur often many minutes before vomiting appears Vomiting Act • deep breath • raising of the hyoid bone and larynx to pull the upper esophageal sphincter open • closing of the glottis to prevent vomitus flow into the lungs, and • lifting of the soft palate to close the posterior nares. • Next comes a strong downward contraction of the diaphragm along with simultaneous contraction of all the abdominal wall muscles. This squeezes the stomach between the diaphragm and the abdominal muscles building the intragastric pressure to a high level. Finally the lower esophageal sphincter relaxes completely allowing expulsion of the gastric contents upward through the esophagus. Chemoreceptor Trigger Zone • “Chemoreceptor Trigger Zone” in the Brain Medulla for Initiation of Vomiting by Drugs(morphine) or by Motion Sickness.