GI histology II Flashcards
(54 cards)
What are the 3 parts of SI?
- Duodenum
- Jejunum
-Ileum
Function of SI
- Move chyme forward
- Continue its digestion with juices secreted and accessory glands
- Absorb the nutrient material released by digestion into the blood and lymph vessels in its mucosa
Describe folding of SI
Four degrees of folding amplify the absorptive surface area of the mucosa
What are the 4 degrees of folding of SI?
- Plicae circulares
- Intestinal villi
- Crypts of Lieberkuhn
- Microvilli on the apical surface of the lining epithelium
Goblet cells
Unicellular mucin secreting glands
Enterocytes Primary function
absorption
Enterocytes
Tall columnar cells with basally positioned nucleus
Enteroendocrine cells
Produce various paracrine and endocrine hormones
Microvilli of enterocytes form brush border and contain
intramembraneous enzymes including lactase, maltase and sucrase.
Paneth cells primary function
Maintain mucosal innate immunity by secreting antimicrobial substances
M cells
modified enterocytes that cover enlarged lymphatic nodules in the lamina propria
Goblet cells
columnar mucus secreting cells
Secretory product of goblet cells contain
80% carbohydrates and 20% proteins, released by exocytosis.
Mucus hydrates to form a protective gel coat to shield the epithelium from mechanical abrasion and bacterial invasion.
Lactase deficiency gives rise to
osmotic diarrhea
What is associated with the microvillus brush border of enterocytes?
the glycocalyx or cell coat.
What is glycocalyx?
a cell surface glycoprotein complex containing mucins and sugars
- Increase surface area
- Protective
- Digestive
- Absorptive
Enterocytes: each microvillus has a
core of vertically oriented actin microfilaments
Actin microfilaments of enterocytes extend into the apical cytoplasm and insert into the
horizontally oriented terminal web and attach to the intracellular density associated with the zonula adherens.
What do junctional compelxed do?
Bind epithelial cells to prevent passage of macromolecules from lumen into the intracellular spaces and lamina propria
The plasma membrane covering the basolateral cell surfaces has no digestive enzymes but is rich in
Na, K dependent ATPase
Celiac disease antibodies against
Gliadin
Celiac disease deficient
enterocyte maturation (immune mediated epithelial damage)
Loss of villi
Enteroendocrine cells in duodenum secrete
Secretin and CCK
Secretin and CCK promote
Pancreatic exocrine secretion
