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Year 2- GIT > Nutrient Digestion and Absorption 2 > Flashcards

Nutrient Digestion and Absorption 2 Flashcards

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1
Q

What is the form of almost all the ingested fat?

A

Triacylglycerol

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2
Q

Where does all fat digestion take place?

A

In the small intestine

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3
Q

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

A

Pancreatic lipase

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4
Q

What does lipase break triacylglycerol down into?

A

Monoglyceride + 2 fatty acids

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5
Q

Are triacylglycerol’s insoluble or soluble in water?

A

Insoluble

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6
Q

Is lipase a water soluble or insoluble enzyme?

A

Water soluble enzyme

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7
Q

How do triacylglycerol’s present?

A

As large lipid droplets

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8
Q

Why is it hard for lipase to completely degrade triacylglycerol?

A

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

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9
Q

Why is the digestion of fat a slow process?

A

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

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10
Q

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

A

Bile salts

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11
Q

Where is bile synthesised?

A

In hepatocytes in the liver

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12
Q

Why do bile salts act as an emulsifier?

A

They have a hydrophilic and a hydrophobic part

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13
Q

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

A

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

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14
Q

What does emulsification mean?

A

Dividing large fat droplets into smaller droplets

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15
Q

What is the benefit of emulsification?

A

Increases the surface area which increases accessibility for lipase action

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16
Q

How can mechanical disruption occur?

A

By contraction of the muscles in the stomach or the intestine

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17
Q

Why is an emulsifying agent required?

A

Prevents the small droplets from gathering back into a larger droplet

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18
Q

Give some examples of emulsifying agents

A

Bile salts
Phospholipids

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19
Q

RECAP- what does amphipathic mean?

A

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

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20
Q

Are hydrophilic substances polar or non-polar?

A

Polar

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21
Q

Are hydrophobic substances polar or non-polar?

A

Non-polar

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22
Q

How do emulsifying agents prevent smaller droplets from joining together?

A

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

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23
Q

Absorption can be enhanced by the formation of what?

A

Micelles

24
Q

Are micelles smaller or larger than emulsion droplets?

A

Smaller

25
Q

What are micelles composed of?

A

Bile salts + phospholipids + monoglycerides + fatty acids

26
Q

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

A

Polar/hydrophilic portion

27
Q

How do micelles cross the intestinal epithelial cells?

A

By diffusion

28
Q

Name to the forms of fat in the blood.

A

Low density lipoprotein
High density lipoprotein

29
Q

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

A

Smooth endoplasmic reticulum

30
Q

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

A

They reformed into triacylglycerol by enzymes

31
Q

What are extracellular fat droplets known as?

A

Chylomicrons

32
Q

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

A

Go through lacteals found between endothelial cells

33
Q

What is the function of lacteal?

A

They absorb fat and fat soluble vitamin cholesterol

34
Q

What are the fat soluble vitamins?

A

K, E, D, A

35
Q

What are the water soluble vitmains?

A

B, C and folic acid

36
Q

How are water soluble vitamins absorbed?

A

By passive diffusion or carrier-mediated transport

37
Q

What are fat soluble vitamins absrobed by?

A

Chylomicrons

38
Q

Is Vitamin B12 hydrophobic or hydrophilic?

A

Hydrophilic

39
Q

How can vitamin B12 be absorbed?

A

Can only be absorbed when bound to an intrinsic factor

40
Q

Where are intrinsic factors synthesised?

A

The stomach

41
Q

Where will the intrinsic factor bind to the vitamin B12?

A

The small intestine

42
Q

Where will the vitamin B12 intrinsic factor complex be absorbed?

A

Distal ileum of small intestine

43
Q

What will a vitamin B12 deficiency cause?

A

Pernicious anaemia.

44
Q

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

A

3 years

45
Q

What happens in pernicious anemia?

A

Failure of red blood cell maturation

46
Q

Where is most of the vitamin B12 stored?

A

Liver

47
Q

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

A

10%

48
Q

Where does the rest of the ingested iron go?

A

Into faeces

49
Q

How is iron transported across the brush border membrane?

A

Via DMT1

50
Q

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

A

Duodenal enterocytes

51
Q

What are the iron ions incorporated into?

A

Ferritin

52
Q

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

A

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

53
Q

What does the iron in blood bind to?

A

Transferrin

54
Q

What is meant by hyperaemia?

A

Increased ferritin levels meaning more iron is bound in enterocytes

55
Q

What is meant by anaemia?

(not the condition exactly so don’t get too excited x).

A

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

56
Q

What is transferrin?

A

A carrier of iron when it’s in the blood

57
Q
A

Year 2- GIT (37 decks)

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