intro to lower GI tract W4 Flashcards
what is defined as the lower GI tract
GI tract beyond the pylorus
3 sections of the small intestine?
duodenum
jejunum
ileum
where does the ileum join the large intestine (colon)?
right iliac fossa
ileo-caecal valve
4 sections of the duodenum?
straight, descending, horizontal, ascending
what section of the duodenum does the pancreas exit from?
descending (second part)
where does the duodenum and jejunum meet
duodenojejunal flexure (beyond sharp turn)
jejunum and ileum transition?
seamless transition
purpose of small intestine
absorb nutrients and water from diet
small intestine mucosa features
folded into millions of villi
increased surface area for absorption
‘carpet-like’ appearance
what does each villus in the small intestine contain
blood vessels and a lymph vessel
name of surface cells in small intestine? features?
enterocytes
microvilli form brush border
small intestine cells?
enterocytes (surface)
goblet cells (secrete mucus)
enteroendocrine cells (secrete hormones)
stem cells (crypts adjacent to villi)
sections of the large intestine?
caecum
colon (ascending, transverse, descending, sigmoid)
rectum
anal canal
features of the rectum
repository for stool
ends at anal canal (transition to squamous mucosa)
anal sphincter - internal (smooth) and external (striated)
features of the colon wall
mucus secreting glands
no villi but crypts
features of the colon wall muscles
grouped into dense strips (taeniae coli) and rings. these are shorter than the bowel and mean pouches (haustra) are formed.
appendix features
variable position
may have a role in gut microflora
what is the peritoneum?
continuous membrane covering most abdominal organs
two layers - visceral and parietal
visceral layer of peritoneum?
lines organs, is their serosa
parietal layer of peritoneum?
lines walls of abdominal cavity
retroperitoneal meaning? which organs are found here?
extraperitoneal and behind the peritoneum
pancreas, kidneys, adrenals, urinary tract, parts of duodenum, colon and rectum
mesentery features?
large fold of parietal peritoneum that is attached to the small intestine and prevents it knotting up (also blood supply)
omentum features?
continuation of the serosa of the stomach. apron which hangs over the intestines. if perforation/inflammation, it can wrap around the segment and seal it off.