Digestion/Absorption of Carbohydrates and Proteins

Question 1

fiber

Answer 1

non-digestible polysaccharides

-pectin and cellulose

Question 2

starch

Answer 2

digestible polysaccharide from plant

Question 3

digestible polysaccharides

Answer 3

starch plants
glycogen animals
amylose straight
amylopectin brainched

Question 4

sucrose

Answer 4

glucose and fructose

Question 5

lactose

Answer 5

glucose and galactose

Question 6

dietary monosaccharides

Answer 6

glucose and fructose

Question 7

carb intestine absorption

Answer 7

only monosaccharides

Question 8

salivary amylase

Answer 8

alpha amylase
-secreted in active form

initiates starch digestion
inactivated by gastric acid

cannot break terminal alpha 1-4 or branch (alpha 1-6)

Question 9

pancreatic alpha amylase

Answer 9

stimulated release by CCK

cannot digest terminal linkage and branch points

Question 10

terminal linkage

Answer 10

alpha 1-4

Question 11

branch point linkage

Answer 11

alpha 1-6

Question 12

membrane digestion of carbohydrates

Answer 12

brush border enzymes (integral membrane)

mostly in proximal jejunum (none in colon)

oligosaccharidases

Question 13

brush border proteins

Answer 13

lactase
glucoamylase (maltase)
surcrase-isomaltase

Question 14

lactase

Answer 14

lactose > glucose + galactose

expression decreases after breast feeding

Question 15

glucoamylase

Answer 15

aka maltase

terminal alpha 1-4 linkage break

Question 16

sucrase-isomaltase

Answer 16

two enzymes

• also breaks terminal alpha 1-4 linkages
• sucrose cleavage
• splits branch points (alpha 1-6)

for alpha limit dextrins

Question 17

alpha limit dextrins

Answer 17

branch points (alpha 1-6)

Question 18

maltotriose and maltose

Answer 18

polymers of glucose that aren’t broken down by alpha amylase

Question 19

absorption of carbs

Answer 19

readily absorbed monosaccharides

-glucose, galactose, fructose

Question 20

SGLT1

Answer 20

Na-glucose co-transporter on apical membrane
-glucose and galactose uptake

driven by Na/K pump (decreases intracellular Na)

Question 21

GLUT5

Answer 21

apical membrane transport of fructose

facilitated diffusion
-in jejunum

Question 22

GLUT2

Answer 22

basolateral membrane protein
-movement of all three - fructose, glucose, galactose

facilitated diffusion

Question 23

lactase deficiency

Answer 23

lactose deficiency

• Sx: cramps, diarrhea (short FA), flatus (CO2)
• colonic bacteria digest lactose

common - non-white ethnicities

epigenetics downregulate through lifetime

Question 24

H2

Answer 24

released in breath - from colonic bacteria metabolism of lactose

basis for hydrogen breath test
-high amounts indicate bacterial fermentation

Question 25

glucose-galactose malabsorption

Answer 25

AA substition in SLT1 -inhibits glucose/galactose uptake diarrhea (osmotic) Tx: no glucose , galactose, lactose in diet -fructose based diet

Question 26

protein digestion

Answer 26

take up AAs or oligopeptides to enterocytes

Question 27

endopeptidase

Answer 27

bonds adjacent to specific AAs | -produce oligopeptides

Question 28

exopeptidase

Answer 28

bonds at N or C terminus | -release single AAs

Question 29

gastric protease

Answer 29

secreted as proenzymes (aka zymogens)

Question 30

pepsinogen

Answer 30

secreted by chief cells of stomach -low pH activation to pepsin inactivated at pH 7 endopeptidase

Question 31

trypsinogen

Answer 31

pancreatic protease activated by jejunal brush border enzyme -enteropeptidase to trypsin (which autoactivates trypsinogen and other pancreatic proteases)

Question 32

trypsin activation?

Answer 32

trypsinogen chymotrypsinogen proelastase procarboxypeptidase A and B

Question 33

chymotrypsin

Answer 33

endopeptidase

Question 34

elastase

Answer 34

endopeptidase

Question 35

carboxypeptidase A and B

Answer 35

exopeptidases

Question 36

enteropeptidase

Answer 36

activates trypsin in jejunum

Question 37

brush border peptidases

Answer 37

lots of them | in small intestine

Question 38

pepsin

Answer 38

endopeptidase

Question 39

PepT1 transporter

Answer 39

transports oligopeptides across enterocyte membrane

Question 40

whole protein absorption

Answer 40

M cells - to peyers patches enterocyte endocytosis in neonate - passive immunity - hormonally mediated closure - corticosteroids

Question 41

oligopeptide absorption

Answer 41

PepT1- H/oligopeptide cotransporter driven by H and Na gradient - Na/K pump - Na in - H out H back in with oligopeptide

Question 42

single AA absorption

Answer 42

some based on Na/K pump | some not based on Na gradient

Question 43

hartnup disease

Answer 43

autosomal recessive defect apical transport neutral AAs pellagra, ataxia, psych abnormalities ``` no treatment (normal oligopeptide absorption) PepT1 ```

Question 44

cystinuria

Answer 44

autosomal recessive defect apical transport basic AA and cysteine kidney stones ``` no treatment (normal oligopeptide absorption) PepT1 ```

Question 45

glucose tolerance test

Answer 45

if given only glucose as carb and still have symptoms oral glucose given, look at blood levels changes

Question 46

hydrogen breath test

Answer 46

carb digestion in colon