chapter 35: small bowel. COPY Flashcards
intestine: nutrient and water absorption
small intestine
intestine: water absorption
large intestine
portions of the duodenum
- bulb (1st portion) - 90% of ulcers here
- descending (2nd) - contains ampulla of Vater (duct of wirsung) and duct of santorini
- transverse (3rd)
- ascending (4th)
portions of the duodenum that are retroperitoneal
descending and transverse portions
transition point of the 3rd and 4th portions of the duodenum
acute angle between the aorta (posterior) and SMA (anterior)
vascular supply duodenum
superior (off gastroduodenal artery) and inferior (off SMA) pancreaticoduodenal arteries
- both have anterior and posterior branches
- many communications between these arteries
100 cm long; long vasa recta, circular muscle folds
- absorbs 95% NaCl and 90% water
- vascular supply: SMA
Jejunum
maximum site of all absorption except for b12 (terminal ileum), bile acids (ileum - non conjugated; terminal ileum - conjugated), iron (duodenum) and folate (terminal ileum)
jejunum
150 cm long, short vasa recta, flat
- vascular supply: sma
ileum
what is absorbed at the intestinal brush border?
maltase, sucrase, limit dextrinase, lactase
normal sizes: small bowel / transverse colon / cecum
3 / 6 / 9 cm
SMA eventually branches into the…
ileocolic artery
cell types of the small intestine
absorptive cells, goblet cells (mucin secretion), paneth cells (secretory granules, enzymes), enterochromaffin cells, runner’s glands, peyer’s patches, m cells
What do goblet cells secrete?
mucin secretion
What do paneth cells secrete?
secretory granules, enzymes
What do enterochromaffin cells secrete?
APUD, 5-hydroxytryptamine release, carcinoid precursor
What do brunner’s cells secrete?
alkaline solution
What do M cells secrete?
antigen-presenting cells in intestinal wall
released into the gut; also in mother’s milk
IgA
small bowel has both heme and Fe transporters
Fe
where is iron absorbed?
duodenum
where is folate absorbed?
terminal ileum
where is b12 absorbed?
terminal ileum
where are bile acids absorbed?
- ileum: non conjugated
- terminal ileum: conjugated