Topic 6.5

Question 1

Daily intake of carbohydrates

Answer 1

300g

Question 2

Main form of intake of carbohydrates

Answer 2

polycarbohydrates

Question 3

Daily intake of proteins

Answer 3

40-100g

Question 4

Daily intake of fats

Answer 4

50-100g

Question 5

Daily intake of dietary fibers

Answer 5

50-100g (not digested)

Question 6

Daily intake of H20

Answer 6

1.5-2L

Question 7

Where does digestion mostly take place?

Answer 7

In the small intestine

Question 8

What are the 3 main mechanisms of digestion?

Answer 8

1. Luminal
2. Brush border
3. Intracellular

Question 9

What are the 2 mechanisms of absorption?

Answer 9

1. Transcellularly

2. Paracellularly

Question 10

What are the 2 main digestive enzymes in the oral cavity?

Answer 10

amylase and lingual lipase

Question 11

Difference between lingual lipase and pancreatic lipase?

Answer 11

lingual lipase can chop off al 3 fatty acids from a triglyceric molecule

Question 12

What can be absorbed in the oral cavity? (4)

Answer 12

• alcohol
• medicines
• nicotine
• dope, narcotics

Question 13

How much protein digestion happens in stomach

Answer 13

15-20%

Question 14

What are the 3 digestive enzymes in the stomach?

Answer 14

• pepsinogen (then pepsin)
• gastric lipase
• salivary amilase still working a bit

Question 15

What are the differences between the salivary and gastric lipases?

Answer 15

they’re the same

Question 16

Which molecules can be absorbed in the stomach?

Answer 16

lipid soluble molecules like alcohol and medicine

Question 17

What makes the small intestine so important for digestion and absorption?

Answer 17

its large surface thanks to circular folds, vili, brush border

Question 18

At what levels does carbohydrate digestion happen in SI?

Answer 18

• Luminal digestion

- Brush border digestion

Question 19

Examples of plant starch molecules (polycarbohydrates)

Answer 19

• amylopectin

- amylase

Question 20

Animal starch?

Answer 20

glycogen

Question 21

What are dietary fibers?

Answer 21

polycarbohydrates that cannot be digested and will be used for the formation of feces

Question 22

What disaccharides in our diet? (2)

Answer 22

Lactose, sucrose

Question 23

How are polysaccharides digested?

Answer 23

by being degraded until they are monosaccharides

Question 24

Which enzyme group digests polysaccharides?

Answer 24

amylase enzymes (mostly pancreatic)

Question 25

Which bond do amylases cleave?

Answer 25

internal alpha (1-4) bond

Question 26

What are the 3 products of amylase enzymes?

Answer 26

- maltose - maltriose - alpha-limit dextrins

Question 27

Which enzyme group will further degrade the glucose polymers?

Answer 27

oligosaccharidases in the brush border

Question 28

4 examples of oligosaccharidases

Answer 28

- maltase - alpha-dextrinase - lactase - sucrase

Question 29

What does alpha dextrinase form?

Answer 29

glucose

Question 30

What does maltase form?

Answer 30

glucose

Question 31

What does lactase form?

Answer 31

galactose + glucose

Question 32

What does sucrase form?

Answer 32

fructose + glucose

Question 33

What does SGLT-1 transport?

Answer 33

- Na+ | - Galactose or glucose

Question 34

What type of transport is SGLT-1?

Answer 34

secondary active transport using gradient provided by Na+/K+ pump

Question 35

What type of transport is GLUT-5?

Answer 35

facilated diffusion

Question 36

What does GLUT-5 transport?

Answer 36

Mainly fructose, but if needed it can also have glucose and galactose as substrates

Question 37

What is GLUT-2 transporting?

Answer 37

Glc, Gal, Frct

Question 38

What type of transport is GLUT-2?

Answer 38

facilated diffusion

Question 39

How much protein do we have to digest on top of intake?

Answer 39

50g

Question 40

How much AA is absorbed and how much is left in the feces

Answer 40

97% absorbed and 2% in feces

Question 41

3 steps of protein digestion in small intestine

Answer 41

1. Luminal phase : pepsin or pancreatic proteases 2. Brush border : proteases 3. Peptidases (inside cell)

Question 42

What are trypsin inhibitors useful for?

Answer 42

They inhibit the autocatalytic activity of trypsinogen so it can't activate itself

Question 43

Which enzyme converts trypsinogen to trypsin?

Answer 43

enterokinase, aka enteropeptidase

Question 44

How much protein is absorbed in the form of AA and in the form of di/tripeptides?

Answer 44

AA : 70-75% | Di/tripeptide : 25-30%

Question 45

How are single AA taken up by enterocytes?

Answer 45

coupled with Na+

Question 46

How are di/tripeptides taken up by enterocytes?

Answer 46

coupled with H+ with PepT1 co transporter

Question 47

How much protein can be taken up intactly by the enterocytes?

Answer 47

Around 1milllionth (200g / n.cm²)

Question 48

How many lipids are added on for digestion due to desquamation?

Answer 48

10-12g

Question 49

How are lipids digested?

Answer 49

1 step : luminal, using gastric, lingual and pancreatic lipases

Question 50

3 isoforms of lipases?

Answer 50

- Lipase - Esterase - Phospholipase A2

Question 51

What does lipase convert

Answer 51

triglyceride to 2 monoglyceride and FA

Question 52

What does PLA2 convert

Answer 52

lecithin to FA + lysolecithin

Question 53

What does esterase convert

Answer 53

Cholesterol ester to FA + cholesterol

Question 54

How are bile acids absorbed? (2)

Answer 54

1. If conjugated : Na+/bile salt symporter | 2. Not conjugated : diffusion

Question 55

What are the 4 ways of absorbing Na?

Answer 55

- nutrient coupled absorption (glucose, AA) - Electroneutral Na/H exchange - Parallel Na/H and Cl/HCO3- echangers - Epithelial Na channel

Question 56

Average daily intake and absorption of Ca

Answer 56

1g and 0.4g

Question 57

Entire iron pool of the body

Answer 57

4g

Question 58

Iron loss / day

Answer 58

0.1g/day

Question 59

2 ways or iron absorption

Answer 59

- organically : in the form of heme then Fe | - inorganically : Fe2+ form by a metal transporter

Question 60

2 vitamin groups

Answer 60

1. fat soluble : A, D; E and K | 2. Water soluble : C, B1, B6, B13

Question 61

How are fat soluble vitamins absorbed?

Answer 61

Passive absorption

Question 62

How are water soluble vitamins absorbed?

Answer 62

Na+ dependant transport

Question 63

Which cells release the intrinsic factor?

Answer 63

Parietal cells