L8 - Digestion and Absorption

Question 1

Which of the following CANNOT pass the intestinal epithelial barrier?
A. Glucose
B. Galactose
C. Fructose
D. Sucrose

Answer 1

D. Sucrose (dissaccharide)

Question 2

Amylose

Answer 2

straight chain polymer of glucose

Question 3

Amylopectin

Answer 3

branched-chain polymer of glucose

Question 4

Which of the following is NOT a dissaccharide?
A. Trehalose
B. Sucrose
C. Lactose
D. Galactose

Answer 4

D. Galactose

Question 5

B1,4-linkage

Answer 5

Can’t be hydrolyzed by human gut floral enzymes

Question 6

Alpha-amylase will hydrolyze
A. Alpha1,6-linkage
B. Alpha1,4-linkage
C. Beta1,4-linkage

Answer 6

B. Alpha1,4-linkage

Straight chain parts

Question 7

What is the name for the branching linkage in starch

Answer 7

alpha1,6-linkage

Question 8

Pancreatic amylase digests a-1,4-bonds yielding a mixture of

Answer 8

1. a-limit dextrins (oligosaccharide)
2. Maltose (disaccharide)
3. Maltotriose (trisaccharide)

Question 9

Name 3 brush border enzymes

Answer 9

1. a-dextrinase - digests a-limit dextrins
2. maltase - digests maltose
3. sucrase - digests maltotriose

Question 10

What brush border enzyme can digest maltotriose AND sucrose?

Answer 10

Sucrase

Question 11

Which of the following requires amylase digestion?
A. Trehalose
B. Sucrose
C. Lactose
D. Starch

Answer 11

D. Starch

Question 12

Glucose + glucose =

Answer 12

Trehalose

Question 13

Glucose + galactose =

Answer 13

Lactose

Question 14

Glucose + fructose =

Answer 14

Sucrose

Question 15

Which brush border enzyme can debranch alpha-1,6-linkages?

Answer 15

alpha-dextrinase

Question 16

What’s the only transporter on the luminal side of the intestinal brush border, that utilizes Na?

Answer 16

SGLT1 (Na/Glc transporter 2ndary active)

Question 17

Which of the following transport glucose and galactose against their concentration gradient, coupled to Na+ influx?
A. GLUT 2
B. GLUT 5
C. SGLT 1
D. SGLT 2

Answer 17

C. SGLT 1

Question 18

Which of the following are basolateral on brush border epithelial cells?
A. GLUT 2
B. GLUT 5
C. SGLT 1
D. B and C

Answer 18

A. GLUT 2

Question 19

Lactose intolerance

Answer 19

Defective or absent lactase. Osmotic diarrhea and dehydration result; lactose pulls water.

Question 20

Which results in decreased absorption of glucose/galactose? 
A. Lactase deficiency
B. SGLT-1 deficiency
C. GLUT 5 deficiency
D. A and B

Answer 20

D. A and B

Lactase deficiency - can’t make glucose/galactose from lactose

SGLT-1 deficiency - can’t absorb gluc/gal into brush border epithelia

Question 21

Which one of these 10 aa’s are NOT essential?

Lys, His, Val, Leu, Ile, Phe, Try, Thr, Met, Pro

Answer 21

Pro

Question 22

Which of the following is NOT an endopeptidase, but an EXOpeptidase?

A. pepsin
B. Trypsin
C. Chymotrypsin
D. Elastase
E. carboxypeptidase

Answer 22

E. Carboxypeptidase

hint: carboxy

Question 23

“What is the key enzyme, located on the brush border, that initiates the process of digestion?”

Answer 23

Enterokinase (activates trypsinogen into trypsin)

Question 24

Trypsin activation yields which 5 active enzymes?

Answer 24

1. Trypsin
2. Chymotrypsin
3. Elastase
4. Carboxypeptidase A
5. Carboxypeptidase B

Question 25

Amino acids co-transport with

Answer 25

Na+

Question 26

Di- and tripeptides co-transport with

Answer 26

H+

Question 27

In what organ does lipid digestion BEGIN?

Answer 27

stomach

Question 28

In what organ does MOST lipid digestion occur?

Answer 28

Small intestine

Question 29

What's the 1st enzyme that is affected by pH imbalance?

Answer 29

Pancreatic lipase

Question 30

Name 3 pancreatic lipolytic enzymes that work at neutral pH

Answer 30

Pancreatic Lipase Phospholipase A2 Cholesterol ester hydrolase note: this is why you get steatorrhea when the pylorus dumps chyme in too fast - acidic stomach contents deactivate these lipolytic enzymes causing fatty poopoo. Could this be a cure for obesity? ;)

Question 31

What do bile acids to do pancreatic lipase?

Answer 31

Inactivates it

Question 32

What does cofactor lipase do?

Answer 32

Anchors pancreatic lipase to fat droplet, even in presence of bile acid. That way bile acids can emulsify, while lipase can do its thing too.

Question 33

Can micelles enter a cell?

Answer 33

no

Question 34

Where is bile reabsorbed into enterohepatic circulation, and by what transporter?

Answer 34

Ileum, ASBT transporter Note: ileal resection promotes lost bile, and steatorrhea since can't make micelles

Question 35

What's cholestyramine?

Answer 35

complexes with bile so you can poop it out, and start from scratch using cholesterol.