Physiology of Carbohydrate and Protein Digestion and Absorption Flashcards Preview

JL Gastrointestinal > Physiology of Carbohydrate and Protein Digestion and Absorption > Flashcards

Flashcards in Physiology of Carbohydrate and Protein Digestion and Absorption Deck (41):
1

What type of digestion in the small intestine is mediated by pancreatic enzymes secreted into the duodenum?

Luminal

2

What kind og digestion in the small intestine is mediated by enzymes situated at the brush border of epithelial cells?

Membrane

3

Wat is the term for the overall process of digestion and absorption?

Assimilation

4

Give an example of luminal hydrolysis of polymer to monomers?

Protein to amino acids

5

Give and example of brushborder hydrolysis of oligomer to monomer?

Sucrose to glucose and fructose

6

Give an example of intracellular hydrolysis?

Peptide

7

Give an example of luminal hydrolysis followed by intracellular resynthesis?

Triacylglycerol to glycerol and fatty acids

8

Name two polymers of glucose?

Starch and glycogen

9

Name two oligosaccharides?

Sucrose and lactose

10

What does glucose + fructose give?

Sucrose

11

What does glucose + galactose give?

Lactose

12

What is more highly branched - amylopectin or glycogen?

Glycogen

13

What must all dietary carbohydrates be converted to for absorption?

Monosaccharides (glucose and fructose)

14

What is the process of starch being broken down to oligosaccharides?

Intraluminal hydrolysis

15

What are alpha-linit dextrins, maltotriose and maltose?

Oligosaccharides

16

What is the process for breaking down oligosaccharides to monosaccharides?

Membrane digestion (at brush border)

17

Name three oligosaccharidases?

Lactase
Maltase
Sucrase-isomaltase

18

What accomplishes starch by intraluminakl hydrolysis to oligosaccharides?

Alpha-amylase (salivary and pacnreatic)

19

What does a-amylase breakdown, and what does it not?

Breaks down linear internal alpha-1,4 linkages but not terminal alpha-1,4,linkages

20

Does the endoenzyme a-amylase produce glucose?

No

21

What enzyme, cannot cleave alpha-1,6 linkages at branch points (in amylopectin) ot alpha-1,4-linkages adjacent to branch points?

Alpha-amylase

22

What are the main class of products from a-amylase?

Oligosaccharides

23

What are integral membrane proteins with a catalytic domain that faces the lumen of the GI tract?

Oligosaccharidases

24

Ohter than lactase, which breaks down lactose to glucose and galactose, what do all other oligosaccharidases cleave?

The terminal alpha-1,4-linkages of maltose, maltotriose and alpha-limit dextrins

25

What oligosaccharidase is unique in that it is the only enzyme that can split the branching alpha-1,6,linkages of alpha-limit dextrins?

Isomaltase

26

Give an example of a disorder caused by impaired carbohydrate digestion?

Lactose intolerance

27

What insufficiency causes lactose intolerance?

Lactase deficiency

28

What is primary lactase deficiency (primary hypolactasia) due to?

Lack of the lactase persistence (LP) allele

29

What is secondary lactase deficiency due to?

Damage to/infection of/ the proximal small intestine

30

Name a rare, autosomal recessive disease with no ability to digest lactose from birth?

Congenital lactase deficiency

31

What are these produced in response to: short-chain fatty acids, hydrogen (can be detected in breath of lactase defiecient people), carbon dioxide and methane?

Produced by colonic microflora when lactose delivered to colon from ileum

32

What are three symptoms of lactase insufficiency?

Bloating
Abdominal Pain
Flatulence

33

What causes acidification of the colon and increased osmotic load - loose stools nad diarrhoea?

Undigested lactose

34

What are the three final products of carbohydrate digestion?

Glucose, galactose and fructose

35

Where does final product absorption occur?

In duodenum and jejunum

36

What is absorbed by secondary active transport mediated by SGLT1?

Glucose and galactose

37

What is absorbed by facilitated diffusion mediated by GLUT5?

Glucose and galactose

38

How is exit for all monosaccharides mediated?

By facilitated diffusion by GLUT2

39

For SGLT1 transport, what must the substrate be like?

A hexose in D conformation
Can form pyranose ring

40

What products do endopeptidases produce?

Oligopeptides (2-6 amino acids)

41

What products do exopeptidases produce?

Single amino acids