Nutrient Digestion and Absorption 2

Question 1

What is the form of almost all the ingested fat?

Answer 1

Triacylglycerol

Question 2

Where does all fat digestion take place?

Answer 2

In the small intestine

Question 3

Which enzyme is involved with fat digestion in the small intestine?

Answer 3

Pancreatic lipase

Question 4

What does lipase break triacylglycerol down into?

Answer 4

Monoglyceride + 2 fatty acids

Question 5

Are triacylglycerol’s insoluble or soluble in water?

Answer 5

Insoluble

Question 6

Is lipase a water soluble or insoluble enzyme?

Answer 6

Water soluble enzyme

Question 7

How do triacylglycerol’s present?

Answer 7

As large lipid droplets

Question 8

Why is it hard for lipase to completely degrade triacylglycerol?

Answer 8

Because it’s a water soluble enzyme and triacylglycerol is insoluble.

Question 9

Why is the digestion of fat a slow process?

Answer 9

Lipase can only act on the surface of a lipid droplet as it’s lipid insoluble and water soluble

Question 10

What helps to turn a large fat globule into smaller fat globules to make it easier to be broken down?

Answer 10

Bile salts

Question 11

Where is bile synthesised?

Answer 11

In hepatocytes in the liver

Question 12

Why do bile salts act as an emulsifier?

Answer 12

They have a hydrophilic and a hydrophobic part

Question 13

Describe the orientation of bile slats and their hydrophobic and hydrophilic parts when they are attached to a fat globule.

Answer 13

Hydrophobic part of bile slat will be facing inward and the hydrophilic part will be facing outwards

Question 14

What does emulsification mean?

Answer 14

Dividing large fat droplets into smaller droplets

Question 15

What is the benefit of emulsification?

Answer 15

Increases the surface area which increases accessibility for lipase action

Question 16

How can mechanical disruption occur?

Answer 16

By contraction of the muscles in the stomach or the intestine

Question 17

Why is an emulsifying agent required?

Answer 17

Prevents the small droplets from gathering back into a larger droplet

Question 18

Give some examples of emulsifying agents

Answer 18

Bile salts
Phospholipids

Question 19

RECAP- what does amphipathic mean?

Answer 19

A molecule has a hydrophobic and hydrophilic part (or polar and non-polar)

Question 20

Are hydrophilic substances polar or non-polar?

Answer 20

Polar

Question 21

Are hydrophobic substances polar or non-polar?

Answer 21

Non-polar

Question 22

How do emulsifying agents prevent smaller droplets from joining together?

Answer 22

The polar or hydrophilic outer layer is not attracted to the other small lipid droplets

Question 23

Absorption can be enhanced by the formation of what?

Answer 23

Micelles

Question 24

Are micelles smaller or larger than emulsion droplets?

Answer 24

Smaller

Question 25

What are micelles composed of?

Answer 25

Bile salts + phospholipids + monoglycerides + fatty acids

Question 26

In a micelle, which part of the molecule would be facing outwards?

Answer 26

Polar/hydrophilic portion

Question 27

How do micelles cross the intestinal epithelial cells?

Answer 27

By diffusion

Question 28

Name to the forms of fat in the blood.

Answer 28

Low density lipoprotein High density lipoprotein

Question 29

After entering epithelial cells, where do fatty acids and monoglycerides go?

Answer 29

Smooth endoplasmic reticulum

Question 30

What happens when fatty acids and monoglycerides are in the SER?

Answer 30

They reformed into triacylglycerol by enzymes

Question 31

What are extracellular fat droplets known as?

Answer 31

Chylomicrons

Question 32

Chylomicrons cannot get through the capillary basement membrane so how do they get through the cells?

Answer 32

Go through lacteals found between endothelial cells

Question 33

What is the function of lacteal?

Answer 33

They absorb fat and fat soluble vitamin cholesterol

Question 34

What are the fat soluble vitamins?

Answer 34

K, E, D, A

Question 35

What are the water soluble vitmains?

Answer 35

B, C and folic acid

Question 36

How are water soluble vitamins absorbed?

Answer 36

By passive diffusion or carrier-mediated transport

Question 37

What are fat soluble vitamins absrobed by?

Answer 37

Chylomicrons

Question 38

Is Vitamin B12 hydrophobic or hydrophilic?

Answer 38

Hydrophilic

Question 39

How can vitamin B12 be absorbed?

Answer 39

Can only be absorbed when bound to an intrinsic factor

Question 40

Where are intrinsic factors synthesised?

Answer 40

The stomach

Question 41

Where will the intrinsic factor bind to the vitamin B12?

Answer 41

The small intestine

Question 42

Where will the vitamin B12 intrinsic factor complex be absorbed?

Answer 42

Distal ileum of small intestine

Question 43

What will a vitamin B12 deficiency cause?

Answer 43

Pernicious anaemia.

Question 44

How long can it take to present with symptoms of pernicious anemia?

Answer 44

3 years

Question 45

What happens in pernicious anemia?

Answer 45

Failure of red blood cell maturation

Question 46

Where is most of the vitamin B12 stored?

Answer 46

Liver

Question 47

How much of the daily iron ingested is absorbed across the intestine and goes into the blood?

Answer 47

10%

Question 48

Where does the rest of the ingested iron go?

Answer 48

Into faeces

Question 49

How is iron transported across the brush border membrane?

Answer 49

Via DMT1

Question 50

Where does the iron go into after getting across the brush border membrane?

Answer 50

Duodenal enterocytes

Question 51

What are the iron ions incorporated into?

Answer 51

Ferritin

Question 52

Why can iron not be released as a free ion and must only be released as part of a complex?

Answer 52

It's highly reactive and corrosive and can damage enterocytes and the intestine

Question 53

What does the iron in blood bind to?

Answer 53

Transferrin

Question 54

What is meant by hyperaemia?

Answer 54

Increased ferritin levels meaning more iron is bound in enterocytes

Question 55

What is meant by anaemia? (not the condition exactly so don't get too excited x).

Answer 55

Decreased ferritin levels meaning more iron is released into the blood.

Question 56

What is transferrin?

Answer 56

A carrier of iron when it's in the blood