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Flashcards in GI5 Deck (35):
1

what are three things that amplifies surface area?

-folds
-villi and crypts
-microvilli

2

the epithelium lining in the small intestine is ____

leaky

3

what part of the crypt contains digestive enzymes?

glycocalyx

4

what cells of the crypt secrete antimicrobial peptides?

paneth cells

5

are there stem cells in the crypt?

yes

6

what layer presents a barrier to diffusion in the gut?

unstirred layer

7

what two things make up the unstirred layer?

-glycocalyx layer
-mucous layer

8

nutrients must pas though what layer in order to be absorbed?

unstirred layer

9

what is the overarching goal of digestion?

-reduce particle size to enable absorption

10

what is hydroysis?

splitting of a chemical bond by the insertion of water

11

what type of bonds are in carbs?

glycosidic bonds

12

what type of bonds are in proteins?

peptide bonds

13

what type of bonds are in fats?

ester bond

14

what type of bonds are in nucleic acids?

phosphodiester bonds

15

what do digestive enzymes do?

catalyze hydrolysis

16

what phase are proteins and starch hydrolyzed?

luminal phase, active withing the gut lumen

17

what phase are polysaccharides and peptides hydrolyzed?

membranous phase, active at the gut epithelial surface

18

where is the enzyme origin for luminal phase?

-salivary glands
-gastric glands
-pancreas

19

where is the enzyme origin for membranous phase?

-apical membrane of enterocytes

20

what is starch comprised of?

amylose and amylopectin

21

is amylose straight or branched?

straight

22

is amylopectin straight or branched?

branched

23

which peptidase can only cleave in the middle of a protein, and cannot release free amino acids?

endopeptidases

24

which peptidase can cleave at the ends and release individual AAs?

exopeptidase

25

what is a key pancreatic zymogen activator?

trypsin

26

at what pH does pepsin have maximal activity?

pH 1-3

27

T/F: the stomach is essential for digestion and survival.

false

28

lactose breaks down into:

glucose and galactose

29

sucrose breaks down into

glucose and fructose

30

starch breaks down into

glucose

31

GLUT5 carriers what?

glucose and fructose

32

SGLT1 carries what?

glucose and galactose

33

enterocytes absorb short peptides and free AAs but release only ___ ___ ___ into the blood.

-free amino acids

34

many uptake uptake mechanisms are coupled to ____ movement.

Na+

35

what is the first step of the absorptive process?

luminal uptake