TBL17 - Duodenum

Question 1

What are plicae circulares? What is formed by projections of the mucosa from the macroscopic folds?

Answer 1

1) Plicae circulares are macroscopic folds of the duodenal mucosa and submucosa
2) The microscopic finger-like villi are formed by projections of the mucosa from the macroscopic folds

Question 2

What forms intestinal crypts and where do they extend into? Where do plicae circulares, villi, and intestinal crypts continue into and what does this allow for?

Answer 2

1) The simple columnar epithelium (to be studied later) dips between the villi to form intestinal crypts that extend in the lamina propria to the muscularis mucosae
2) Plicae circulares, villi, and intestinal crypts continue into the jejunum and ileum thereby increase the surface area for nutrient absorption along the small intestine

Question 3

What is the duodenal submucosa filled with? What do ducts of these glands do?

Answer 3

1) The duodenal submucosa is filled with distinctive mucous glands (of Brunner)
2) Ducts of the glands deliver mucous with high bicarbonate ion concentrations into the duodenal lumen to buffer the acidic discharge from the pylorus

Question 4

How many layers of smooth muscle constitute the muscularis externa of the small intestine?

Answer 4

Like the stomach, two layers of smooth muscle constitute the muscularis externa of the small intestine

Question 5

What treatment effectively promotes healing of peptic ulcers?

Answer 5

1) Most peptic ulcers are caused by Helicobacter pylori infection, but they may also result from use of NSAIDs and alcohol
2) Antibiotic treatment therefore often promotes healing