Topic 15: Digestive System - Intestine

Question 1

From where does the intestine start and end?

Answer 1

pyloric sphincter to ileocaecal valce

Question 2

What are the three segments of the intestine?

Answer 2

1. Duodenum
2. jejunum
3. ileum

Question 3

What is the duodenum? (2)

Answer 3

• first fold (short) - retroperitoneal
• extra glands here secrete alkaline mucous to protect against stomach acid

Question 4

What is the jejunum?

Answer 4

middle section

Question 5

What does the ileum contain and why?

Answer 5

• group of lymph nodules called Peyer’s patches
• prevent infection of small intestine + bacteria from entering blood

Question 6

The intestine is specialized into segments to increase absorption surface area. What are these segments called?

Answer 6

• Plicae circulares
• Villi
• microvilli

Question 7

What are plicae circulares?

Answer 7

• submucosa thrown into folds

Question 8

What are villi?

Answer 8

• projections of mucosa into lumen

Question 9

What do villi contain? (2)

Answer 9

• blood capillaries
• lymph capillaries (called lacteals that absorb fats)

Question 10

What are microvilli? (2)

Answer 10

• brush border on enterocytes (simple columnar)
• extend into lumen

Question 11

Where are enteroendocrine cells, and what do they secrete?

Answer 11

• within epithelium
• secrete hormones secretin and cholescystokinin