Nutrient Digestion II (Fats, Vitamins and Minerals) Flashcards Preview

GI System > Nutrient Digestion II (Fats, Vitamins and Minerals) > Flashcards

Flashcards in Nutrient Digestion II (Fats, Vitamins and Minerals) Deck (40):
1

Where does all fat digestion occur and what enzyme does so?

Small Intestine
Lipase - Made in the pancreas

2

How do triacylglycerols present?

Large lipid droplets

3

What is special about the lipid droplet and lipase relationship?

Lipid droplets and insoluble in water but lipase is a water soluble enzyme so digestion only occurs at the droplet surface

4

What does lipase cleave triacylglycerols into?

Monoglyceride + Fatty Acids x2

5

What is emulsification?

The dividing of large lipid droplets into smaller droplets resulting in an increased surface area and accessibility to lipase action

6

How are droplets made smaller?

Mechanical disruption - Smooth muscle grinding and mixing luminal contents

7

How are smaller droplets prevented from reforming into largers ones?

Emulsifying agent (Comes from bile)
Biles salts and phospholipids emulsify smaller fat globules
*Phospholipids are amphipathic so they repel other small lipid droplets*

8

How is lipase digestion enhanced?

By the use of micelles

9

What are micelles?

Similar to emulsion droplets but much smaller
*Bile salt + Monoglycerides + Fatty Acids + Phospholipids*

10

What happens to micelles?

They are not absorbed but instead release small amounts of Fatty Acids and Monoglycerides to diffuse across the plasma membrane

11

When does the micelle destabilise?

When it enters the microclimate outside the cell

12

Triacylglycerol droplets coated with amphipathic protein are transported where, how and what happens to them there?

To Golgi Apparatus via vesicles from RER
Exocytosed into the ECF at the serosal membrane

13

What is a chylomicron?

Extracellular far droplet containing phospholipids, cholesterol and fat-soluble vitamins
*A lipoprotein that is present in the blood after digested fat has been absorbed from the small intestine*

14

Where do Chylomicrons go?

Into lacteals between endothelial cells

15

What can chylomicrons not pass through?

Tight junctions between capillaries to prevent fat entering the blood

16

What are the fat-soluble vitamins?

A, D, E & K

17

What are the water-soluble vitamins?

B, C & Folic acid - Either absorbed by passive diffusion or carrier-mediated transport

18

What is special about Vitamin B12?

It must bind to intrinsic factor in the stomach and travel to the ileum where a specific transport mechanism recognises the complex itself - not the B12

19

What does B12 have an affect on?

Red blood cell maturation - Can give functional anaemia

20

Why can a sign of gut specific deficiency be delayed?

There is 3 years worth of B12 in the liver

21

What effect can bowel resection have on B12?

B12 transport mechanism is removed and anaemia will ensue 3 years down the line

22

What is iron absorbed across into the blood?

Brush border membrane via DMT1 - 10% a day is ingested across the intestine into blood

23

What does DMT1 transport and where to?

Mainly Iron but also Lead and Cadmium into duodenal enterocytes

24

What are enterocytes?

Simple columnar epithelial cells found in the small intestine

25

What are iron ions incorporated into?

Ferritin

26

What happens to unbound iron?

Transported across the serosal membrane into the blood

27

What does iron in blood bind to?

Transferrin

28

What does transferrin do?

Stops iron becoming free radicals and transports it to the liver

29

How often does the small intestine lining renew itself?

Every 5 days

30

What is the regulator of iron stasis?

The gut

31

What does hyperaemia lead to?

Increased ferritin levels
More iron bound in enterocytes

32

What does anaemia lead to?

Decreased ferritin levels and more iron released into the blood

33

What three glands secrete saliva?

Parotid
Submandibular
Sublingual

34

What is the main component of saliva?

Water - 99% to soften, moisten and dilute particles

35

What are mucins and what is their function?

Mucus + Water
Lubricant function

36

Is amylase found in saliva?

Yes

37

What is a Lysozyme(Natural bacteria)?

Bacteriocidal that cleaves the polysaccharide component of the bacterial cell wall

38

Where does α-amylase come from?

Serous alveolus

39

What effect does the parasympathetic nervous system have on salivary secretion?

Creates a profuse watery salivna
*Cranial nerves VII (Facial) & IX (Glossopharyngeal)

40

What effect does the sympathetic nervous system have on salivary secretion?

Creates a small viscous amount of saliva that is high in protein
*If separated a β-2 adrenoreceptor agonist will give you a high amylase content and a α-1 adrenoreceptor agonist will make the saliva gloopy*