Lecture 22

Question 1

What gets delivered into the SI?

Answer 1

Acidic chyme

Question 2

What protects the SI from the acidic chyme?

Answer 2

Epithelium with goblet cells on surface, mucus-secreting glands in submucosa and neutralising pH (bicarbonate) from pancreas

Question 3

What does the liver secrete for digestion?

Answer 3

Bile

Question 4

What does the pancreas secrete for digestion?

Answer 4

Enzymes

Question 5

What are the three regions of the small intestine?

Answer 5

Duodenum, jejunum, ileum

Question 6

What is the shortest region of the SI?

Answer 6

Duodenum, ~25cm

Question 7

What are the respective lengths of the jejunum and ileum?

Answer 7

~2.5m and ~3.5m

Question 8

What is the total length of the SI?

Answer 8

~6m

Question 9

What is the function of the duodenum?

Answer 9

To receive chyme from the stomach, enzymes & bicarbonate from the pancreas and bile from the liver

Question 10

What is the function of the jejunum and ileum?

Answer 10

Digestion and absorption

Question 11

What section of the SI lies retroperitoneal

Answer 11

Duodenum

Question 12

What holds the jejunum and ileum in place?

Answer 12

The mesentery

Question 13

What is the function of the mesentery?

Answer 13

To allow movement but prevent tangling

Question 14

What does the mesentery contain?

Answer 14

Blood vessels, nerves, lymphatics and fat

Question 15

What is the mesentery made up of?

Answer 15

Peritoneum which makes it slippery

Question 16

What enters the mesenteric veins?

Answer 16

Nutrient-rich, deoxygenated blood

Question 17

Where do the mesenteric veins drain?

Answer 17

To the hepatic portal vein

Question 18

Where do the lymph lacteals of the mesentery drain?

Answer 18

Into the cisterna chyil -> thoracic duct -> left subclavian vein

Question 19

What is a requirement of the SI in order to fully carry out digestion and absorption?

Answer 19

A very large surface area

Question 20

How is a large surface area achieved in the SI?

Answer 20

Length, plicae circulares, villi, microvilli

Question 21

What are plicae circulares?

Answer 21

Permanent large folds of the SI wall, a core of submucosa with overlying mucosa

Question 22

How many muscularis layers does the SI contain?

Answer 22

2; inner circular and outer longitudinal

Question 23

What are villi?

Answer 23

Part of the mucosa, found on the surface of the plicae circulares

Question 24

What are villi made of?

Answer 24

A core of lamina propria that contains lymph lacteals for products fat digestion and a capillary network for products of protein and carbohydrate digestion

Question 25

What allows villi movement?

Answer 25

Muscularis mucosae

Question 26

What are microvilli?

Answer 26

Extensions off the simple columnar epithelial cells of the enterocytes on their apical surface

Question 27

What does the microvilli form?

Answer 27

A brush boarder

Question 28

What is the function of the microvilli brush boarder?

Answer 28

Contact digestion involving enzymes

Question 29

What does the plasma membrane contain?

Answer 29

Proteins; channels and transporters for its semipermeable membrane

Question 30

What do the tight junctions between the epithelial cells allow?

Answer 30

Allow small molecules to diffuse through

Question 31

What are the five types of SI cells?

Answer 31

Enterocytes, goblet cells, paneth cells, endocrine cells, stem cells

Question 32

What are the enterocytes?

Answer 32

Absorptive cells

Question 33

What is the function of the goblet cells?

Answer 33

Secrete mucous for protection and lubrication

Question 34

What are the paneth cells?

Answer 34

Granule containing cells with antibacterial enzymes

Question 35

What is the function of the endocrine cells?

Answer 35

To secrete hormones

Question 36

What is the function of the stem cells?

Answer 36

To make all cell types in order to replenish cells in tract

Question 37

What is an intestinal crypt?

Answer 37

Part of the mucosa which projects downwards like a gland. Keeps cells safe and decreases damage

Question 38

What is the function of the intestinal crypt?

Answer 38

To increase surface area

Question 39

What separates the small and large intestines?

Answer 39

The ileocecal valve, which regulates the passage of material into the large intestine via a sphincter