Small Intestine Flashcards
what is included in the small intestine?
duodenum
jejunum
ileum
what are villi?
finger like projections on epithelium
what are crypts of Lieberkuhn?
crypts between adjacent villi
what are enterocytes?
the principle absorptive cell
most numerous cell in small intetsine
tall columnar cells with a brush border
what domgobelt cells do?
produce mucin to protect epithelium and lubricste passageway for material
what are panted cells?
cells found at the base of Lieberkuhn crypts
protective function - regulate bacterial flora
what are enteroendocrine cells?
cells that produce hormones
contribute to control of secretion and motility
what are stem cells?
cells that divide to replenish epithelium
found at bottom of crypts of Lieberkun
where does the duodenum start and end?
starts at the pylors
ends at duodenojejunal junction
what does the duodenum receive?
chyme from the stomach
what shape is the duodenum?
C
how many parts is the duodenum split into?
4
superior
descending
horizontal
ascenidng
what vertebral level is the superior duodenum?
L1
what vertebral level is the descending duodenum?
L1-3
what vertebral level is the horizontal duodenum?
L3
what vertebral level is the ascending duodenum?
L3-2
what part pf the duodenum is intraperitoneal?
superior duodenumw
what parts of the duodenum are retroperitoneal?
descending
horizontal
ascending
where is the descending duodenum?
it curves inferiorly around the head of the pancreas
it is marked by major duodenal papilla where bile and pancreatic secretions enter from the ampulla of Vater
where is the horizontal duodenum?
travels laterally to the left, crossing over the inferior vena cava and aorta
inferior to the pancreas
posterior to the superior mesenteric artery and vein
where is the ascending duodenum?
ascends and curves anteriorly to join the jejunum at a sharp turn - duodenojejunal flexure
what does the duodenum secret?
peptide hormones - i.e gastrin, CCK
where does pain from a duodenal ulcer tend to present?
epigastric region
where are Brunner’s glands?
in the submucosa of the duodenum
- only glands in digestive tract below the oesophagus
what do Brunner’s glands do?
when stimulated by chyme they produce a thin alkaline mucous to neutralise the chyme
what part of the duodenum does the superior gastroduodenal artery supply?
the foregut - the bit proximal to the major duodenal papilla
what part of the duodenum does the inferior pacreaticoduodenal artery (branch of superior mesenteric artery) supply?
the midgut - the bit distal to the major duodenal papilla
where do the veins of the duodenum drain?
they follow the major arteries and drain into the hepatic portal vein
is the jejunum and ileum intraperitoneal or retroperitoneal?
retroperitonela
how long is the jejunum?
around 3m
how long is the ileum?
around 4m
where does the jejunum start?
at the duodenaljujunal jucntion
around L2
where does the ileum end?
ileocaecal junction
is there a junction between the jejunum and ileum?
no clear junction
macroscopically different
what is the mucosa of the jejunum like?
highly folded - plicae circularis
what is the mucosa of the ileum like in comparison to the jujunum?
much smoother
what is the histology of the jejunum?
tallest villi on permanent circular folds of mucosa (plicae circulars)
infrequent lymphoid follicles
what is the histology of the ileum?
shorter villi
aggregations of lymphoid tissue - Peyer’s patches
where are Payer’s patches found?
in the submucosa of the ileum often extending to the lamina propria
what is the arterial blood supply of the jejunum and ileum?
from the superior mesenteric artery via the jejunal and ileal arteries
what is the venous drainage of the jejunum and ileum?
jejunal and ileal veins drain into the superior mesenteric vein
which drains into the hepatic portal vein
