Lecture 22: The Small Intestine

Question 1

What are the 3 main regions of the small intestine?

Answer 1

• Duodenum
• Jejunum
• Ileum

Question 2

What is the total length of the small intestine?

Answer 2

6m

Question 3

Where is the initial segment of the duodenum?

Answer 3

Retroperitoneal

Question 4

What is the small intestine held in place by?

Answer 4

The Mesentery

Question 5

What does the Mesentery allow?

Answer 5

Allows movement but prevents the SI from getting tangled

Question 6

What does the Mesentery contain?

4

Answer 6

• Arteries
• Veins
• Nerves
• Lymphatics

Question 7

What is a property of the chyme received by the SI?

Answer 7

Acidic

Question 8

What protects the epithelium in the SI?

2

Answer 8

• Mucous secreting cells

- Glands in the submucosa

Question 9

What is the only section of the SI to contain glands in its submucosa?

Answer 9

Duodenum

Question 10

What neutralises the acidic chyme in the SI?

Answer 10

Bicarbonate

Question 11

Where is bicarbonate produced to neutralise chyme?

Answer 11

Pancreas

Question 12

What are Plicae Circulares (Circular folds)?

Answer 12

Permanent large folds of the small intestine

Question 13

What is the core of the Place Circulares made of?

Answer 13

Submucosa with overlying mucosa

Question 14

What is found on the Plicae circulares?

Answer 14

Numerous villi

Question 15

What does the Muscularis mucosae allow the villi to do?

Answer 15

Allow them to wiggle back and forth

Question 16

What is the core of the Villi made from?

Answer 16

Fibrous Connective Tissue (lamina propria)

Question 17

What do the Villi contain?

2

Answer 17

• Lymph lacteal

- Capillary network

Question 18

What does the lymph lacteal drain?

Answer 18

Products of fat digestion

Question 19

What does the capillary network drain?

Answer 19

Products of protein and carbohydrate digestion

Question 20

What does nutrient rich deoxygenated blood in the small intestine enter?

Answer 20

The mesenteric veins

Question 21

What do the mesenteric veins drain into?

Answer 21

Hepatic portal vein

Question 22

What pathway do lymph lacteals ultimately drain into?

Answer 22

Into the Cisterna Chyli, thoracic duct and then left subclavian vein

Question 23

What do mesentery do?

Answer 23

Connect organ to body wall

Question 24

What is the epithelium of the SI?

Answer 24

Simple columnar

Question 25

What is on the apical surface of the SI epithelium?

Answer 25

Microvilli

Question 26

What is the role of the microvilli?

Answer 26

Increase the surface area

Question 27

Where are Gycocalyx?

Answer 27

In the microvilli brush border

Question 28

What is the Gycocalyx made of?

2

Answer 28

• Glycoproteins

- Branched filaments

Question 29

What is the function of the Gycocalyx?

Answer 29

Tether enzymes

Question 30

What does contact digestion involve?

Answer 30

Enzymes attached to the brush border

Question 31

What is the plasma membrane?

Answer 31

A selectively permeable membrane

Question 32

What is contained in the plasma membrane?

3

Answer 32

• Proteins
• Channels
• Transporters

Question 33

What holds epithelial cells together?

Answer 33

Tight junctions

Question 34

What can diffuse through tight junctions?

Answer 34

Small molecules

Question 35

What cells are in the epithelium of the small intestine?

5

Answer 35

• Enterocytes
• Goblet cells
• Stem cells
• Paneth cells
• Endocrine cells

Question 36

What do enterocytes do?

Answer 36

Absorptive cells

Question 37

What do goblet cells do?

Answer 37

Secret mucous for protection

Question 38

What do stem cells do?

Answer 38

Make all cell types

Question 39

What do Paneth cells do?

Answer 39

Secrete granules, antibacterial enzymes

Question 40

What do Endocrine cells do?

Answer 40

Secrete hormones