Small Intenstines

Question 1

What are the 3 parts of the small intestine?

Answer 1

Duodenum
Jejunum
Ileum

Question 2

Where is the jejunum located?

Answer 2

Upper left quadrant

Question 3

Where is the ileum located?

Answer 3

Lower right quadrant

Question 4

How does the intestinal wall compare between ileum and jejunum?

Answer 4

Jejunum has a thicker intestinal wall

Question 5

How does the blood supply differ between the ileum and jejunum?

Answer 5

Ileum

• shorter vasa recta
• more arcades (arterial loops)

Jejunum

• longer vasa recta
• less arcades

Question 6

What artery supplies the small intestines?

Answer 6

Superior mesenteric artery

Question 7

What is the venous drainage of the small intestines?

Answer 7

Superior mesenteric vein

Question 8

What are the properties of chyme as it exits the duodenum?

Answer 8

Isotonic
Neutral
Digestion nearly complete

Question 9

How is the surface area increased in the intestines?

Answer 9

Permanent folds = plicae circulares/valvulae conniventes

Mucosa folded into villi

Microvilli form a brush border

Question 10

What makes up the intestinal epithelia?

Answer 10

Epithelial cells

Intestinal glands

Question 11

What epithelial cells are present in the intestines?

Answer 11

Enterocytes
Goblet cells
Enteroendocrine cells

Question 12

What type of cells are enterocytes?

Answer 12

Tall columnar cells

Question 13

What is the role of enterocytes?

Answer 13

Absorption

Question 14

What are intestinal glands also known as?

Answer 14

Crypts of Lieberkühn

Question 15

What is the structure of intestinal glands?

Answer 15

Stem cells at the base - migrate to surface

Paneth cells at base

Question 16

What is the role of Paneth cells?

Answer 16

Produce antimicrobial peptides

Question 17

What sugars can be absorbed?

Answer 17

Only monosaccharides

Question 18

How is glucose absorbed?

Answer 18

With sodium

Question 19

What are the common dietary carbohydrates?

Answer 19

Starch (polysaccharides)
Lactose (disaccharide)
Sucrose (disaccharide)

Question 20

What does starch consist of?

Answer 20

Straight chains = amylose

Branched chains = amylopectin

Question 21

What are the bonds in amylose?

Answer 21

Alpha 1-4 bonds

Question 22

What are the bonds in amylopectin?

Answer 22

Alpha 1-6 bonds

Question 23

What enzyme breaks the α1-4 bonds?

Answer 23

Amylase

Question 24

What is produced by amylase breaking α1-4 bonds on amylose?

Answer 24

Maltose (glucose-glucose)

Question 25

What is produced by amylase breaking α1-4 bonds on amylopectin?

Answer 25

Alpha dextrins - short branched chains of glucose

Question 26

What enzyme breaks α1-6 bonds?

Answer 26

Isomaltase

Question 27

Where is isomaltase produced?

Answer 27

Enterocytes in the brush border

Question 28

What enzyme breaks down maltose?

Answer 28

Maltase

Question 29

What enzyme breaks down lactose?

Answer 29

Lactase

Question 30

What enzyme breaks down sucrose?

Answer 30

Sucrase

Question 31

How is glucose absorbed by brush border?

Answer 31

With Na+ | Via SGLT1 transporter + GLUT2

Question 32

How is galactose absorbed by brush border?

Answer 32

SGLT1 + GLUT2

Question 33

How is fructose absorbed by brush border?

Answer 33

GLUT5 + GLUT2

Question 34

How is protein digested in the stomach?

Answer 34

Pepsinogen released from chief cell Pepsinogen converted to pepsin by HCL Pepsin breaks down proteins

Question 35

How is protein digested in the duodenum?

Answer 35

Pancreas releases enzymes as zymogens Trypsinogen is converted to trypsin by enteropeptidase Trypsin activates other proteases

Question 36

What enzyme activates trypsinogen?

Answer 36

Enteropeptidase

Question 37

What are the main proteases?

Answer 37

Trypsin Chymotrypsin Elastase Carboxypeptidase

Question 38

How is protein digested at the brush border?

Answer 38

Enterocytes express peptidases Break proteins down to amino acids Short peptides absorbed by PepT1 Amino acids absorbed with Na+ cotransporter

Question 39

What is the movement of water in the small intestines?

Answer 39

Water is absorbed - driven by Na+

Question 40

How is the osmotic gradient maintained?

Answer 40

Na+ moved by active transport out of cell Na+ diffuses into epithelial cells with glucose/amino acids

Question 41

How is water secretion driven?

Answer 41

Chloride movement

Question 42

Where is vitamin B12 absorbed?

Answer 42

Ileum

Question 43

What can cause vit B12 deficiency?

Answer 43

Lack of intrinsic factor Lak of stomach acid Inadequate dietary intake Inflammation of ileum

Question 44

What causes lactose intolerance?

Answer 44

Deficiency of lactase in the brush border

Question 45

What is the effect of lactose intolerance?

Answer 45

Lactose not absorbed - remains in gut lumen - creates high osmotic effect - water not absorbed = diarrhoea - lactose fermented in gut = flatus/bloating

Question 46

What are the symptoms of IBS?

Answer 46

Abdo pain Bloating Flatulence Diarrhoea/constipation

Question 47

What is coeliac disease?

Answer 47

Immune response to the gliadin fraction of gluten

Question 48

What is the effect of coeliac disease?

Answer 48

Damages mucosa of intestines - absence of villi - lengthening of crypts - impaired digestion

Question 49

What are the symptoms of coeliac disease?

Answer 49

Diarrhoea Weight loss Flatulence Anaemia

Question 50

How is coeliac disease investigated?

Answer 50

IgA antibodies to - muscle endomysium - ttg Upper GI endoscopy

Question 51

How is coeliac disease managed?

Answer 51

Gluten free diet