Carbohydrate digestion

Question 1

Salivary amylase

Answer 1

Starts digestion

hydrolyzes alpha 1,4 linkage to yield disaccharides (maltose and alpha limit dextrin)

Question 2

Pancreatic amylase

Answer 2

Highest concentration in duodenal lumen

Hydrolyzes starch to oligosacchardes and disaccharides

Question 3

Oligosaccharides hydrolases

Answer 3

Brush border of intestine,
Rate limitng step in carb digestion,
produce monosaccharides from oligo and disaccharides.

Question 4

Carbohydrate absorption

Answer 4

Only monosaccharides (glucose, galactose, fructose) absorbed by enterocytes.

Glucose and galactose taken up by SGLT1 (Na+ dependent)
Fructose taken by facilitated diffusion by GLUT5
All transported to blood by GLUT2

D-xylose absorption test: distinguishes GI mucosal damage from other causes of malabsorption.