Digestion and absorption of nutrients

Question 1

Carbohydrates

Answer 1

• Products of digestion
  Glucose, galactose, fructose
• Site of absorption
  Small intestine
• Mechanism
  Na+ glucose co-transport
  Na+ galactose co-transport
  Facilitated diffusion

Question 2

Proteins

Answer 2

• Products of digestion
  Amino acids, dipeptides and tripeptides
• Site of absorption
  Small intestine
• Mechanisms
  Na+ amino acid co-transport
  H+ dipeptide co-transport
  H+ tripeptide co-transport

Question 3

Lipids

Answer 3

• Products of digestion
  Fatty acids, monoglycerides, cholesterol
• Site of absorption
  Small intestine
• Mechanism
  Bile salts form micelles in the small intestine
  Diffusion of fatty acids, monoglycerides, and cholesterol into intestinal cells
  Re-esterification in the cell to triglycerides and phospholipids
  Chylomicrons form in the cell (requiring apoprotein) and are transferred to lymph

Question 4

Fat soluble vitamins (Lipophilic)

Answer 4

• Site of absorption
  Small intestine
• Mechanism
  Micelles form with bile salts and products of lipid digestion
  Diffusion into the intestinal cell

Question 5

Water soluble vitamins (Hydrophilic)- Vitamin B12

Answer 5

• Site of absorption
  Small intestine and ileum (Vit B12)
• Mechanism
  Na+ dependent co-transport
  Intrinsic factor

Question 6

Bile salts

Answer 6

• Site of absorption
  Ileum
• Mechanism
  Na+ bile salt co-transport

Question 7

Ca2+

Answer 7

• Site of absorption
  Small intestine
• Mechanism
  Vitamin D- dependent Ca2+ binding protein

Question 8

Fe2+

Answer 8

• Products of digestion:
  Fe3+ reduced to Fe2+
• Site of absorption
  Small intestine
• Mechanism
  Binds to apoferritin in the intestinal cell
  Binds to transferrin in blood