The Intestines Flashcards
What is the foregut?
Supplied by the coeliac trunk.
Oesophagus, stomach, 1st part of the duodenum down to the common dile duct.
What is the midgut?
Supplied by the superior mesenteric artery.
Distal part of the duodenum, jejunum, ileum, caecum, descending colon, 2/3 transverse colon.
What is the hindgut?
Supplied by the inferior mesenteric artery.
Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum.
Ends half way down the anal canal.
What is the junction where the duodenum meets the jejunum called?
The duodenojejunal flexure
What is the junction where the small intestine meets the large intestine called?
The iliocaecal junction
Roughly how long are the small intestines?
6m
What makes up the small intestines?
Duodenum (5%)
Jejunum (40%)
Ileum (~60%)
What is segmentation?
Mass contraction of a specific region of the intestines to allow mass movement
What is peristalsis?
Small contractions to allow slow, controlled movement of chyme through the intestines.
What shape is the duodenum?
C-shaped
What are the 4 parts of the duodenum?
1st - superior part. Mostly horizontal, lies anterolateral to the L1 vertebrae
2nd - descending part. Runs along L2 and L3. Curves around the head of the pancreas.
3rd - Inferior part. Crosses anterior to the inferior vena cava and aorta.
4th - ascending part. Begins at left of L3 and rises to superior border of L2.
What is the function of the Suspensory Ligament of Treitz?
To hold in place the duodenojejunal flexure
Where is the pancreas in relation to the duodenum?
Pancreas head sits in the C-shape of the duodenum.
Where is the superior mesenteric artery in relation to the duodenum?
It passes posterior to the duodenum.
What are plicae circulares and where are they found?
Permanent fold of mucous membrane.
Found in the lower part of the duodenum and mainly in the jejunum.
What are the blood vessels in the serosa of the jejunum called and describe their structure.
Vasa recta.
Long straight arteries - anatomical end arteries.
The mesentery has very little fat so blood vessels can be seen clearly.
Are there plicae circulares in the ileum?
No - very few
What is the blood supply of the ileum in the serosa?
Very short vasa recta.
Mesentery has a lot of fat so you cannot see the blood vessels through.
What is a defining feature of the ileum that is not present in any other part of the GI tract?
Peyer’s Patches - islands of lymphoid tissue in the wall.
What is the lymphatic drainage of the duodenum?
Via the pancreatoduodenal and superior mesenteric nodes.
What is the lymphatic drainage of the jejunum and ileum?
Super mesenteric nodes
Give the 3 distinctive features of the large intestine.
Teniae coli - longitudinal muscle is redeuced into 3 bands which cause puckering of the colon.
Haustra - saclike divisions caused by teniae coli.
Epiploic appendages - fat filled pouches. Extensions of the peritoneum covering the bowels.
Give 4 functions of the large intestines.
Absorption of water and electrolytes.
Minimal digestion by bacteria
Mass peristaltic movement (2/3 times/day)
Segmentation moves faeces to rectum
What is the caecum?
Blind-ended space.
Opening at the bottom connects to the vermiform appendix.
What is the arterial supply of the duodenum?
Foregut part - supplied by the gastroduodenal artery (branch of the common hepatic artery which branches from the coeliac trunk)
Midgut - supplied by inferior pancreatoduodenal artery (branch of the superior mesenteric artery)
What is the arterial supply of the jejunum and ileum?
Superior mesenteric artery
What arteries supply the ascending and descending colon?
Ascending = right colic artery Descending = left colic artery
