Nutrient Digestion I (Carbs + Proteins)

Question 1

What is the digestive process for complex carbohydrates to monosacchardies?

Answer 1

Starch - Complex carbs are digested (hydrolysed) by salivary and pancreatic amylases

Cellulose - Broken down by gut bacteria (cellulase)

Question 2

What are the mechanisms to absorb monosaccharides across intestinal epithelial cells?

Answer 2

• Monosaccharides are absorbed across the gut epithelium using transporters

Glucose & Galactose - SGLT symporter + Na to move across apical membrane and GLUT2 to move across basolateral membrane

Fructose - GLUT-5 absorbs across the apical membrane and GLUT-2 abosrbs across the basolateral membrane

Question 3

What are the digestive processes for converting proteins to small peptides and amino acids?

Answer 3

• Proteases & peptidases are the enzymes which break down proteins or peptides into amino acids

Question 4

What are the mechanisms of absorption for amino acids and small peptides?

Answer 4

• Amino acids are transported across the apical cell membrane together with Na using the SAAT1 transporter
• Dipeptides are transported across the apical membrane using PepT1