Nutrient Absorption Flashcards Preview

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Flashcards in Nutrient Absorption Deck (47):
1

How can water obstruct nutrient absorption?

It forms a layer at the mucosal wall with H-bonds when undisturbed

2

Impediment to nutrient absorption presented by lack of flow in gut

Water forms layer around intestinal wall with H-bonds.

3

Brush-border membrane

Microviliated apical tip of enterocytes in small intestine

4

Which cells secrete mucus in stomach?

Goblet cells

5

Which cells secrete acid in stomach?

Parietal cells

6

Which cells secrete pepsinogen in stomach?

Chief cells

7

Average lifespan of an enterocyte

3-8 days

8

Migration of entreocytes:
1)
2)
3)

1) Stem cells located in crypts
2) Migrate upwards towards vili
3) Differentiate as migrate

9

What do crypt cells secrete?

Water, electrolytes

10

Celiac disease

Gluten causes autoimmune disease
Results in epithelium on villi dying

11

Enzyme that breaks down polysaccharides

Amylase

12

Macromolecule broken down by amylase

Polysaccharides

13

Environment in which amylase works the best

Neutral pH

14

Efficiency of amylase in mouth

Poor
Food not broken down enough for amylase to access much surface area

15

Method of digestion in stomach

Peristalsis grinds food against pylorus to break it down

16

Where does amylase become effective?

In the duodenum
Bicarbonate neutralises acid

17

Hormones released when food enters duodenum

Secretin
Cholecystokinin

18

Role of secretin

Activates water secretion
Activates bicarbonate secretion
Inhibits stomach emptying

19

Action of secretion

Enters blood, stimulates pancreas

20

Cholecystokinin role

Stimulates pancreatic amylase release into duodenum

21

Types of absorbable sugars

Glucrose, galactose, fructose

22

Maltose

2xGlucose

23

Sucrose

Glucose+Fructose

24

Lactose

Glucose+Galactose

25

How do glucose and galactose cross apical membrane?

Sodium-glucose linked transporter (SGLT)

26

What powers the sodium-glucose linked transporter?

Sodium gradient across endothelial wall

27

What converts pepsinogen to pepsin?

Low pH

28

Endopeptidase

Breaks bonds within a polypeptide chain

29

Limit of endopeptidases

Can't produce individual amino acids

30

Where does fat sit in the stomach?

On top of carbs and proteins

31

Which pancreatic proteases are released upon cholecystokinin signalling?

Trypsin, chymotrypsin

32

Factors released upon cholecystokinin signalling

Pancreatic proteases

33

Exopeptidases

Remove amino acids from the ends of proteins

34

Types of exopeptidases

Carboxypeptidases
Aminopeptidases

35

How are pancreatic proteases secreted?

As proenzymes

36

How is protrypsin converted to trypsin?

Enteropeptidase in the brush-border membrane

37

Enzyme activated by enteropeptidase in the brush-border membrane

Protrypsin --> trypsin

38

Which enzymes are activated by trypsin?

Chymotrypsinogen --> Chymotrypsin
Procarboxypeptidase --> Carboxypeptidase

39

What converts chymotrypsinogen to chymotrypsin?

Trypsin

40

What converts procarboxypeptidase to carboxypeptidase?

Trypsin

41

Which factor stimulates trypsin release?

Cholecystokinin

42

What is the pathway for secreted chymotrypsin?

Cholecystokinin --> Protrypsin --> Trypsin --> Chymotrypsinogen --> Chymotrypsin

43

Types of exopeptidases in the brush-border membrane

Aminopeptidases

44

Where are fats mostly broken down?

Duodenum

45

Which fat can stimulate CCK release?

Free fatty acids

46

An effect of CCK release

Feel sated, release bile (for fat digestion)

47

Effect of bile on fats

Emulsification