Lecture 5 - Digestion and Absorption of Carbohydrates

Question 1

In the oral cavity, a-amylase is an ___________ that randomly cleaves internal a(1-4) glucosidic bonds.

Answer 1

endoglucosidase

Question 2

Chyme moves through the duodenum into the small intestine to stimulate the release of _____ and _____.

Answer 2

secretin and CCK

Question 3

Where does the pancreatic phase of carbohydrate digestion occur?

Answer 3

lumen of the small intestine

Question 4

Where does the disaccharidase phase of carbohydrate digestion occur?

Answer 4

mucosal brush border cells

Question 5

Cholecystokinin (CCK) stimulates the release of:

Answer 5

pancreatic a-amylase (and other digestive enzymes) that cleaves a-(1,4) glucosidic bonds

Question 6

3 products generated by a-amylase in the small intestine are:

Answer 6

1. maltose
2. glucose
3. limit dextrins

Question 7

Which is NOT a product generated by a-amylase in the small intestine?

A. Maltose
B. Glucose
C. Maltase
D. Limit dextrins

Answer 7

C - Maltase is a disaccharidase embedded in the glycocalyx

Question 8

___________ is an a-glucosidase that hydrolyzes maltose to 2 molecules of glucose.

A. Lactase
B. Maltase
C. Maltosase
D. Dextrinase
E. Sucrase

Answer 8

B

Question 9

_______ is a B-galactosidase that cleaves lactose to galactose and glucose.

A. Lactase
B. Maltase
C. Maltosase
D. Dextrinase
E. Sucrase

Answer 9

A

Question 10

What is the function of Mucin secretion by Goblet Cells?

Answer 10

provides a protective coating for the disaccharidases

Question 11

______ transports glucose and galactose from the lumen into the intestinal mucosal cell.

A. SGLT1
B. GLUT5
C. GLUT2
D. GLUT4
E. GLUT3

Answer 11

A

Question 12

_______ transports fructose from the lumen into the intestinal cell.

A. SGLT1
B. GLUT5
C. GLUT2
D. GLUT4
E. GLUT3

Answer 12

B

Question 13

________ transports all 3 hexoses from the intestinal cytosol into the portal circulation.

A. SGLT1
B. GLUT5
C. GLUT2
D. GLUT4
E. GLUT3

Answer 13

C

Question 14

Carbohydrates are absorbed from the intestinal lumen in the:

Answer 14

upper jejunum

Question 15

Which is NOT located in the brush border membrane?

A. SGLT1
B. GLUT5
C. GLUT2

Answer 15

C - GLUT2 is located in the basolateral membrane

Question 16

Which glucose transporter in the GLUT family has the highest affinity and rate of transport for glucose?

Answer 16

GLUT3 - supplies energy to the brain even at low blood glucose levels

Question 17

Which glucose transporter is stimulated by insulin?

Answer 17

GLUT4 - enriched in fat cells, skeletal muscle, heart muscle

Question 18

Which glucose transporter has a low affinity and high capacity for glucose transport?

Answer 18

GLUT2 - enriched in hepatocytes, pancreatic B-cells, kidney, and the basolateral membrane

Question 19

Which glucose transporter is enriched in red blood cells and endothelial cells of the blood brain barrier?

Answer 19

GLUT1

Question 20

3 diagnostic tests for lactose intolerance include:

Answer 20

1. Direct Assay for Enzyme
2. Blood Glucose after Lactose Load
3. Hydrogen Breath Test after Lactose Load