Flashcards in Histology of the Small and large intestines Deck (41):
What is chyme
semifluid mass from stomach to duodenum
What are plicae circulares
they are IN the wall,
includes the mucosa and submucosa
-begin in duodenum and disappear mid ileum
What are villi
extensions of mucosa that increase surface area
What forms the crypts of Lieberkun?
the villi, they extend deep into the mucosa
How can we tell if what we are looking at is a gland or not
if it goes all the way down to the muscularis mucosa, it's a gland
What are crypts of Lieberkuhn?
simple tubular glands that increase intestinal surface area
-formed by ivaginations of mucosa between adjacent intestinal cilli
What are microvilli?
evaginations of the apical part of the enterocytes to increase surface area
-produce a brush border on the apical border of ENTEROCYTES
What are enterocytes?
epithelial cells lining the lumen
What is the border between mucosa and submucosa?
What is muscularis externa responsible for?
segmentation and peristalsis
What is the serosa?
a thin layer of loose CT covered by visceral peritoneum (mesothelium)
Which layer is the main distribution site of blood and lymphatic flow?
What are the 2 capillary plexuses in the small intestine?
villus and pericryptal capillary networks
What does the villus capillary plexus supply?
intestinal villus and upper portion of the crypts of lieberkuhn
What does the pericryptal capillary plexus supply?
the lower half of the crypts of lieberkuhn
What conveys Chyle (lymph-containing lipids) from the intestine to lymph circulate (thoracic duct)?
-within a villus
What controls the motility of the small intestine?
the ANS through submucosal and myenteric plexi
Where does the intrinsic input come from?
the mucosa and muscle wall of the small intestine
Where does the extrinsic input come from?
the CNS through parasympathetic nerve trunks (vagus N.)
What cell is specific to the duodenum?
-few goblet cells and leaf like villi
Where are the brunner's glands located?
in the submucosa
What is a special characteristic of the jejunum?
well developed plicae circulares
-NO brunner's glands or peyer's patches
-more goblet cells
What is a special characteristic of the Ileum?
-LOTS of goblet cells
What kind of epithelium lines the crypts of lieberkuhn?
What are the 4 kinds of cells found int he crypt of lieberkuhn?
1.) absorptive cells, or ENTEROCYTES
2.) goblet cells
3.) paneth cells
4.) enteroendocrine cells
*and stem cells I guess
What do the enterocytes have in their membranes?
enzymes! to digest carbs
What do goblet cells do?
secrete mucus via exocytosis
What do enteroendocrine cells do?
secrete peptide hormones controlling several functions of the GI system
What are the 3 things that are secreted from enteroendocrine cells?
What does gastrin do?
stimulates gastric motility, HCL (parietal cells), and insulin
What does secretin do?
Stimulates pancreatic bicarb secretion and enhances insulin release
-opposite of gastrin except for the insulin part
What does CCK do?
acts on pyloric sphincter to slow emptying, stimulates release of bile and pancreatic enzymes
What do paneth cells do?
secrete antimicrobial proteins to limit bacteria-enterocyte contact
-enzymatic degradation of bacterial wall or disrupt the bacterial inner membrane
What is Crohn's disease
it's when neutrophils get into the crypts of lieberkuhn and destroy the intestinal glands
What is the major function of enterocytes in the large intestine?
transport of Ions and Water
Where do we stop seeing plicae circulares or villi?
beyond the ileocecal valve
-BUT there's lots of straight tubular glands to lubricate
What cellular process removes water and concentrated the chyme into semisolid feces?
active transport of sodium
What is the main feature of microvilli of the large intestine?
What does aldosterone do?
increases the absorption of sodium
What does the crypts of lieberkuhn have in the large intestine?
goblet cells, eneteroendocrine, and stem cells
*NO PANETH CELLS* those are in the ileum