GI system: L27 - The small intestine

Question 1

In what division what the small intestine does most absorption take place?

Answer 1

Jejunum.

Question 2

Describe the structure of the small intestine’s adventitia.

Answer 2

This is serosa like that of the stomach’s for jejunum and ileum. Almost all of the duodenum is outside of the peritoneal cavity, and this retroperitoneal portion has an adventitia of supporting tissue.

Question 3

Describe the structure of the small intestine’s muscularis.

Answer 3

Has the regular 2 layers of circular inner layer of muscle and longitudinal layer.

Question 4

Describe the structure of the small intestine’s submucosa.

Answer 4

Same composition to that of the stomach. However, it is arranged into folds called ‘plicae circulares’ (along with the mucosa). These folds into the lumen of the small intestine increase surface area.

Question 5

Describe the structure of the small intestine’s mucosa.

Answer 5

Folded into plicae circulares. The lamina propria and epithelium of the mucosa are folded into villi. Each villus contains a capillary and lacteal (lymph capillary) in the lamina propria. The capillaries transport the products of digestion of dietary proteins and carbohydrates while the lacteals transport the dietary fats.

Question 6

What are the shape of the cells on epithelial cells of the small intestine wall? What is on the epithelial layer?

Answer 6

Simple columnar, specialised for absorption. They have projections called microvilli, which also increase surface area.

Question 7

What cell secrete mucous in the small intestine?

Answer 7

Goblet cells secrete mucous to protect against digestive enzymes.

Question 8

What do neuroendocrine cells do and where are they found?

Answer 8

Endocrine cells are found on the base of villi. They secrete hormones like secretin and cholecystokinin that help to control digestive processes.