Large Intestine

Question 1

What makes up the large intestines?

Answer 1

Caecum 
Ascending colon 
Transverse colon 
Descending colon 
Sigmoid colon 
Rectum 
Anal canal

Question 2

What epithelium lines the large intestines?

Answer 2

Columnar epithelium

Question 3

What are the roles of the large intestines?

Answer 3

Removes water from indigestible gut contents
Production of some vitamins
Temporary storage

Question 4

Is the ascending colon intra or retro peritoneal?

Answer 4

Retroperitoneal

Question 5

Is the transverse colon intra or retroperitoneal?

Answer 5

Intraperitoneal - has its own mesentery = transverse mesocolon

Question 6

Is the descending colon intra or retroperitoneal?

Answer 6

Retroperitoneal

Question 7

Is the sigmoid colon intra or retroperitoneal?

Answer 7

Intraperitoneal - has its own mesentery

Question 8

Is the rectum intra or retroperitoneal?

Answer 8

Upper 1/3 - intraperitoneal

Middle 1/3 - retroperitoneal

Lower 1/3 - no peritoneum

Question 9

What is the arterial supply to the midgut?

Answer 9

Superior mesenteric artery

Question 10

What are the branches of the SMA?

Answer 10

Jejunal arteries
Ileal arteries 
Ileo-colic artery
Right colic artery 
Middle colic artery

Question 11

What do the jejunal arteries supply?

Answer 11

Jejunum

Question 12

What do the ileal arteries supply?

Answer 12

Ileum

Question 13

What does the ileo-colic artery supply?

Answer 13

Caecum

Question 14

What does the right colic artery supply?

Answer 14

Ascending colon

Question 15

What does the middle colic artery supply?

Answer 15

Transverse colon

Question 16

What is the arterial supply to the hindgut?

Answer 16

Inferior mesenteric artery

Question 17

What are the branches of the IMA?

Answer 17

Left colic artery
Sigmoid arteries
Superior rectal artery

Question 18

What does the left colic artery supply?

Answer 18

Descending colon

Question 19

What do the sigmoid arteries supply?

Answer 19

Descending colon

Sigmoid colon

Question 20

What does the superior rectal artery supply?

Answer 20

Upper 1/3 rectum

Question 21

What is the venous drainage of the midgut?

Answer 21

Superior mesenteric vein

Question 22

What is the venous drainage of the hindgut?

Answer 22

Inferior mesenteric vein

Question 23

What is the venous drainage of the rectum?

Answer 23

Upper 1/3 - superior rectal vein -> IMV

Middle/lower 2/3 - systemic venous system

Question 24

What is the difference in the muscle of large intestine compared to the small intestine?

Answer 24

External longitudinal muscle is incomplete

Question 25

What are teniae coli?

Answer 25

Three distinct bands of smooth muscle on the large intestines

Question 26

What are haustra?

Answer 26

Sacculations caused by contraction of the teniae coli

Question 27

How is water absorbed in the large intestines?

Answer 27

Facilitated by ENaC Tighter tight junctions - creates bigger gradient so more water absorbed

Question 28

What induces water absorption in the large intestines?

Answer 28

Aldosterone

Question 29

What is inflammatory bowel disease?

Answer 29

Group of conditions characterised by idiopathic inflammation of the GI tract

Question 30

What are the 2 main conditions in IBD?

Answer 30

Crohn's disease | Ulcerative colitis

Question 31

Where can Crohn's affect?

Answer 31

Anywhere in GI tract - commonly ileum

Question 32

How thick is the inflammation in Crohn's?

Answer 32

Transmural

Question 33

Is Crohn's inflammation continuous?

Answer 33

No -skip lesions

Question 34

What are the gross pathological features of Crohn's?

Answer 34

``` Skip lesions Hyperaemia Mucosal oedema Cobblestone appearance Fistulae ```

Question 35

What are the microscopic pathological features of Crohn's?

Answer 35

Granuloma formation

Question 36

Where can UC affect?

Answer 36

Begins in rectum

Question 37

How thick is the inflammation in UC?

Answer 37

Mucosa only

Question 38

Is UC continuous inflammation?

Answer 38

Yes

Question 39

What are the pathological changes in UC?

Answer 39

Crypt abscesses Reduced number of goblet cells Pseudopolyps Loss of haustra

Question 40

What is the potential sign of Crohn's on a barium follow through?

Answer 40

String sign of kantour