Digestion and absorption

Question 1

How is glucose absorbed

Answer 1

Apical membrane of enterocyte has SGLT1, sodium dependent hexose co-transporter. Secondary active transport make use of sodium gradient maintained by Na+/K+ ATPase

Basolateral membrane, GLUT 2 facilitated or simple diffusion

Question 2

How is fructose absorbed

Answer 2

Apical membrane: GLUT 5

Basolateral: GLUT 2 , simple diffusion

Question 3

How is galactose absorbed

Answer 3

Same as glucose, SGLT 1 (apical), GLUT 2 (basolateral)

Question 4

How is starch digested

Answer 4

Amylase break alpha 1,4 internally to form maltose, maltotriose and alpha-limit dextrin
then the remaining terminal apha 1,4 and alpha 1,6 are broken by membrane bound enzyme

Question 5

What is the absorbable form of carb

Answer 5

glucose, fructose, galactose

Question 6

what are the two forms of starch

Answer 6

amylose (unbranched)

amylopectin (highly branched)

Question 7

Why is lactose digestion of particular importance

Answer 7

only lactase can break it down, while other carbs have overlapping enzyme specificity , lactase deficiency —> lactose intolerance (in new born or adults in late life)