Flashcards in GI system II Deck (33):
What are the four layers of the GI tube?
1. Mucosa2. Submucosa3. Muscularis externa4. Adventitia or serosa
Which GI tube layers have CT associated with them?
1. Serosa2. Adventitia
What is the difference between the serosa and adventitia?
Serosa has an additional outer component (mesothelium)
What makes up the mucosa?
1. Epithelium on basal lamina2. Lamina propria3. Muscularis mucosae
What are the characteristics of the lamina propria?
1. CT, glands, vessels, lymphatic tissue2. Lymphatic vessels with segmental differences
What are the characteristics of the muscularis mucosae?
1. Two layers of smooth muscle (inner circular and outer longitudinal)2. Contraction wrinkles mucosa to increase SA
What are the characteristics of the submucosa?
1. Dense irregular CT2. Glands are present in esophagus and duodenum3. Meissner's plexus
What are the characteristics of the muscularis externa?
1. Two layers of smooth muscle (inner circular and outer longitudinal)2. Contraction results in peristalsis3. Myenteric (Auerbach's) plexus
What is the submucosal plexus?
1. Parasympathetic postganglionic meurons and sympathetic postganglionic fibers2. Regulates glandular activity, blood flow, muscularis mucosae, and is sensory
What is the myenteric plexus?
1. Located in muscularis externa2. Parasympathetic postganglionic neurons and sympathetic postganglionic fibers3. Controls peristalsis
What kind of epithelium makes up the mucosa of the esophagus?
Stratified squamous nonkeratinized
Where are the cardiac esophageal glands found?
Lamina propria proximally and distally
Where are the esophageal glands proper (seromucous) found?
What are the characteristics of the muscularis externa in the esophagus?
1. Upper 5% - skeletal2. Upper esophagus - skeletal and smooth3. Lower 50% - smooth
How is the adventitia / serosa arranged in the esophagus?
1. Thoracic - adventitia2. Abdominal - serosa
What is Barrett's esophagus?
1. Metaplastic columnar epithelium with goblet cells (PAS / Alcian blue stain highlight goblet cells)2. Demarcation of stratified squamous and simple columnar epithelia3. At risk for progression to adenocarcinoma
What is achalasia?
1. Damage to certain neurons in the myenteric plexus causes constriction of the LES2. Distal constricted esophagus demonstrates a characteristic bird's beak appearance
What are the characteristics of the mucosa in the stomach?
1. Simple columnar with mucous cells2. Gastric pits3. Glands empty into gastric pits4. Gland regions isthmus, neck, fundus5. Few lymphatic vessels; in lamina propria around muscularis mucosae
What are gastric pits?
Invaginations of surface epithelium into lamina propria
What are the characteristics of the fundus and body mucosa?
1. Short gastric pits2. Gastric glands are long with diverse cell population3. Glands divided into isthmus, neck, base
What are the cells of the isthmus region of gastric glands?
1. Surface epithelial cells - secrete mucous2. Parietal (oxyntic) cells - secrete HCl and intrinsic factor in response to gastrin 3. Stem cells are located here
In which region of the gastric gland are stem cells located?
What are the features of the neck region of the gastric gland?
1. Mucous neck cells2. Many parietal cells, some chief cells3. Enteroendocrine cells
What are the features of the base region of the gastric gland?
1. Contains many chief cells - pepsinogen is secreted in response to Ach2. Enteroendocrine cells - hormone secreting cells3. Some mucous cells4. Few parietal cells
What are the features of the cardiac mucosa of the stomach?
1. Short gastric pits2. Long glands in lamina propria
What are the features of the pyloric mucosa of the stomach?
1. Deep gastric pits2. Short glands3. Enteroendocrine cells (G cells secreting gastrin)
What are defense mechanisms against ulcers?
1. Mucous and bicarbonate layer2. Cell renewal3. Alkaline tide
What is the difference between ulcer and erosion?
1. Erosion - confined to mucosal layer2. Ulcer - penetrates into submucosa
What is the gastroduodenal sphincter?
Pyloric sphincter; thickening of muscularis externa, chiefly inner circular layer
What are the structures that increase the SA of the small intestine?
1. Plicae circulares - permanent folds of submucosa and mucosa2. Intestinal villi - mucosa3. Microvilli
What are the signature features of gluten enteropathy?
1. Enterocytes are disarrayed2. Villus atrophy3. Crypt (intestinal gland) hyperplasia4. Inflammation of lamina propria
What are features of Zollinger-Ellison syndrome?
1. Caused by gastrin-secreting tumor2. Tumor may arise in the duodenum, pancreas, or peripancreatic soft tissue