Small Intestine

Question 1

What are the parts of the duodenum?

Answer 1

Superior, descending, horizontal and ascending.

Question 2

Is the duodenum intraperitoneal or retroperitoneal?

Answer 2

Retroperitoneal.

Question 3

Is the jejunum intraperitoneal or retroperitoneal?

Answer 3

Intraperitoneal.

Question 4

Is the ileum intraperitoneal or retroperitoneal?

Answer 4

Intraperitoneal.

Question 5

Where does the duodenum sit in relation to the pancreas?

Answer 5

The duodenum curves round the head, body and ucinate process of the pancreas.

Question 6

Is the horizontal part of the duodenum anterior or posterior to the IVC and aorta?

Answer 6

Anterior.

Question 7

What muscle is found at the duodenojejunal junction and what is its function?

Answer 7

The suspensory muscle of the duodenum. It aids movement of contents into jejunum.

Question 8

What is the significance of the major duodenal papilla and where is it found?

Answer 8

Found 2/3 of the way down the ascending duodenum.

It marks the transition from the foregut to the midgut and is where the hepato-pancreatic ampulla enters the duodenum.

Question 9

In what part of the abdomen can the jejunum and ileum be found?

Answer 9

Jejunum - umbilical

Ileum - hypogastrium/pelvis

Question 10

Compare the jejunum and ileum, commenting on thickness of the wall.

Answer 10

Jejunum thick, ileum thin.

Question 11

Compare the jejunum and ileum, commenting on size of vasa recta.

Answer 11

Jejunum longer, ileum shorter.

Question 12

Compare the jejunum and ileum, commenting on number of arcades.

Answer 12

Jejunum less, ileum more.

Question 13

Compare the jejunum and ileum, commenting on colour.

Answer 13

Jejunum is red, ileum is pink.

Question 14

What epithelium is found in the small intestine?

Answer 14

Tall columnar absorptive cells - enterocytes.

Question 15

Name two mucus secreting structures of the small intestine.

Answer 15

Brunner’s glands - alkaline mucus to neutralise stomach acid.

Goblet cells - found throughout mucosa.

Question 16

The mucosa of the small intestine has many features to increase absorption. Name 3 features.

Answer 16

Plicae Circularis - large circular folds.

Villi - smaller folds on plicae.

Microvilli

Question 17

What glands can be found between villi?

Answer 17

Crypts of Lieberkuhn.

Question 18

What cells can be found in the crypts of Lieberkuhn and what are there functions?

Answer 18

Paneth cells - defensive function - contain secretory granules containing lysosomes, defensins and phospholipase.

Stem cells - divide every 2-3 days to replace cells.

Endocrine cells - produce secretin, somatostatin, GLP-1 and serotonin

Question 19

What is the function of secretin?

Answer 19

Inhibits gastrin, pancreatic acini to secrete H20 and HCO3 when HCl is sensed in the duodenum.

Question 20

What is the function of somatostatin?

Answer 20

Inhibits gastrin, secretin, CCK, VIP, insulin and glucagon.

Question 21

What are Peyer’s patches?

Answer 21

Aggregated lymphoid follicles found in the ileum.

Question 22

What arteries supply the duodenum?

Answer 22

Proximal to the major duodenal papilla - gastroduodenal artery.

Distal to duodenal papilla - inferior pancreaticoduodenal artery (first branch from sup mesenteric).

Question 23

What artery supplies the jejunum and ileum?

Answer 23

Jejunal and ileal branches of the superior mesenteric artery.

Question 24

What veins drain the small intestine?

Answer 24

The inferior pancreaticoduodenal veins drain the duodenum (and pancreas).

The jejunal and ileal vein drain the jejunum and ileum.

These veins go into the superior mesenteric vein, which joins with the splenic vein to form the hepatic portal vein.

Question 25

What is the lymphatic drainage of the duodenum?

Answer 25

Pancreaticoduodenal nodes and superior mesenteric nodes.

Question 26

What are the functions of the substances released by endocrine cells?

Answer 26

Secretin - stimulates H20 and HC03 release from the pancreas.

Somatostatin - inhibitory

GLP - delays gastric emptying

Serotonin - affects gastric muscles

Question 27

What is the lymphatic drainage of the jejunum and ileum?

Answer 27

Superior mesenteric nodes