Lecture 6: The lower GI tract Flashcards
What are the three regions of the small intestine?
Dueodenum
Jejunum
Ileum
What is the length of the duodenum?
25-30cm
What is the length of the jejunum?
2.5 metres
What is the length of the ileum?
3.5 metres
What is the principal function of the small intestine?
Absorption and digestion of products
How long is the small intestine in adults?
4-6m
What is the name of the folds of the mucosa and submucosa in the small intestine?
Plicae circulares
What are the finger-like projections in the small intestine?
Villi
What structure on the enterocytes increases surface area?
Microvilli
Where are lymphoid aggregations found within the layers of the small intestine?
Lamina propria
What name is given to the 200+ lymphoid aggregations in the small intestine’s lamina propria?
Peyer’s patches
What shape are Peyer’s patches?
Groups of lymphoid follicles which bulge ‘dome-like’ into the lumen
Where along the small intestine are Peyer’s patches most prominent and least prominent?
Fewest in duodenum
Most in terminal ileum
What is located in the germinal center of a Peyer’s patch?
Proliferating and maturing B cells, surrounded by mantle of resting lymphocytes
What makes up the area between follicles in peyer’s patches?
T lymphocytes
What is the specialised follicular epithelium overlying peyer’s patches specialised for?
Anitgen uptake
What do M cells in Peyer’s patches do?
Act as bacterial sensors, activating the immune system
Peyer’s patches are connected to what type of lymph node?
Mesenteric lymph node
What type of cell lines the small intestine?
Simple columnar epithelium
What is the most common type of cell in the small intestine?
Enterocytes
What is the structure of the enterocyte cells?
Tall columnar
Surface microvilli
What do goblet cells in the small intestine produce?
Mucin
What cells are found at the base of crypts in the small intestine?
Paneth cells
What do paneth cells contain/
Eosinophilic apical granules
What do neuroendocrine cells produce?
Locally acting hormones
Where are stem cells found within the small intestine?
At the base of crypts
What do stem cells in the small intestine do?
Divide to replenish other cell types
What is another type of cell found within the small intestine, no mentioned above?
Intraepithelial lymphocytes
What is the function of the glycocalyx?
To provide additional surface for adsorption
What does the glycocalyx consist of?
Acidic mucopolysaccharides and glycoproteins