Flashcards in Lower GI Tract Deck (61)
What is the small intestine the principal site for?
For absorption of digestion products by cells of the epithelial lining
What three regions make up the small intestine
the duodenum, the jejunum and the ileum
How long is the small intestine in adults
The mucosa and the submucosa of the small intestine is of what shape?
What is the plicae circularis (folds of Kerckring)?
They are large deep permanent folds of the mucosa and sub mucosa
What are the villi
finger like projections
where are the microvilli found in the small intestine?
On the enterocytes
What is an enterocyte?
Enterocytes, or intestinal absorptive cells, are simple columnar epithelial cells found in the small intestine.
What is the lamina propria?
rich vascular and lymphatic network to absorb products of digestion
What is the prominent feature of the small intestine found in the lamina propria called?
What are peyers patches?
Small masses of lymphatic tissue
Where are peyers patches found least and most in the small intestine?
Least in duodenum and most prominent in terminal ileum
How would you describe the shape of the peyers patches?
Groups of lymphoid nodules which bulge dome like into the lumen
What is the function of the peyers patches?
Function as an immune surveillance system
What cells make up the peyers patches?
Germinal centre of proliferating and maturing b cells surrounded by a mantle of small resting lymphocytes
What is the epithelium overlying the domes of the peyers patches specialised for?
What is the germinal centre of the peyers patches made of cell wise?
what is the mantle of the peyers patches made of cell wise?
What type of epithelium cell are villi lined by?
simple columnar epithelium
The epithelium cells between villi of the small intestine invaginate to form what structure?
The crypts of Lieberkuhn
What types of cells are present in the crypts? list six
Enterocytes, goblet cells, paneth cells, neuroendocrine cells, stem cells and intraepithelial lymphocyte
what are enterocytes?
most numerous, tall columnar and have surface microvilli
What do goblet cells present in the crypts produce?
what are paneth cells
form base of crypts, eosinophilic apical granules. release lysozyme, phospholipase a2, defensins
what are neuroendocrine cells
produce locally acting hormones,
what are stem cells
differentiate into the other five types of cells mentioned
what is the function of intraepithelial lymphocytes
list three locally acting hormones the endocrine cells may secrete in the small intestine
somatostatin, secretin and serotonin
What is the duodenum?
the first part of the small intestine