The Intestines

Question 1

What is the foregut?

Answer 1

Supplied by the coeliac trunk.

Oesophagus, stomach, 1st part of the duodenum down to the common dile duct.

Question 2

What is the midgut?

Answer 2

Supplied by the superior mesenteric artery.

Distal part of the duodenum, jejunum, ileum, caecum, descending colon, 2/3 transverse colon.

Question 3

What is the hindgut?

Answer 3

Supplied by the inferior mesenteric artery.
Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum.
Ends half way down the anal canal.

Question 4

What is the junction where the duodenum meets the jejunum called?

Answer 4

The duodenojejunal flexure

Question 5

What is the junction where the small intestine meets the large intestine called?

Answer 5

The iliocaecal junction

Question 6

Roughly how long are the small intestines?

Answer 6

6m

Question 7

What makes up the small intestines?

Answer 7

Duodenum (5%)
Jejunum (40%)
Ileum (~60%)

Question 8

What is segmentation?

Answer 8

Mass contraction of a specific region of the intestines to allow mass movement

Question 9

What is peristalsis?

Answer 9

Small contractions to allow slow, controlled movement of chyme through the intestines.

Question 10

What shape is the duodenum?

Answer 10

C-shaped

Question 11

What are the 4 parts of the duodenum?

Answer 11

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.

Question 12

What is the function of the Suspensory Ligament of Treitz?

Answer 12

To hold in place the duodenojejunal flexure

Question 13

Where is the pancreas in relation to the duodenum?

Answer 13

Pancreas head sits in the C-shape of the duodenum.

Question 14

Where is the superior mesenteric artery in relation to the duodenum?

Answer 14

It passes posterior to the duodenum.

Question 15

What are plicae circulares and where are they found?

Answer 15

Permanent fold of mucous membrane.

Found in the lower part of the duodenum and mainly in the jejunum.

Question 16

What are the blood vessels in the serosa of the jejunum called and describe their structure.

Answer 16

Vasa recta.
Long straight arteries - anatomical end arteries.
The mesentery has very little fat so blood vessels can be seen clearly.

Question 17

Are there plicae circulares in the ileum?

Answer 17

No - very few

Question 18

What is the blood supply of the ileum in the serosa?

Answer 18

Very short vasa recta.

Mesentery has a lot of fat so you cannot see the blood vessels through.

Question 19

What is a defining feature of the ileum that is not present in any other part of the GI tract?

Answer 19

Peyer’s Patches - islands of lymphoid tissue in the wall.

Question 20

What is the lymphatic drainage of the duodenum?

Answer 20

Via the pancreatoduodenal and superior mesenteric nodes.

Question 21

What is the lymphatic drainage of the jejunum and ileum?

Answer 21

Super mesenteric nodes

Question 22

Give the 3 distinctive features of the large intestine.

Answer 22

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.

Question 23

Give 4 functions of the large intestines.

Answer 23

Absorption of water and electrolytes.
Minimal digestion by bacteria
Mass peristaltic movement (2/3 times/day)
Segmentation moves faeces to rectum

Question 24

What is the caecum?

Answer 24

Blind-ended space.

Opening at the bottom connects to the vermiform appendix.

Question 25

What is the arterial supply of the duodenum?

Answer 25

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)

Question 26

What is the arterial supply of the jejunum and ileum?

Answer 26

Superior mesenteric artery

Question 27

What arteries supply the ascending and descending colon?

Answer 27

Ascending = right colic artery
Descending = left colic artery