digestion and absorption of carbohydrates.

1. VIGNESWARAN G B.Sc. , M.Sc.
ASSISTANT PROFFESSOR,
DEPARTMENT OF BIOCHEMISTRY
NANDHA DENTAL COLLEGE AND HOSPITAL

2. Process of conversion of large food
particles into smaller nutrients
thereby aids their absorption and
nourishes the body

3. Is a group of organs
which helps in digestion
and absorption process
Digestive system
Alimentary
canal (or) GI
tract
Accessory
organs

4. Dietary carbohydrates
 Digestion of carbohydrates
Starch
Glycogen
Cellulose
Lactose
Sucrose
Glucose
Fructose
DIGESTION
INTESTI
NE
MOUTH
STOMAC
H

5. MOUTH
 Carbohydrate digestion starts in mouth
 Catalyzed by salivary amylase (ptyalin)
 Digestibility can be enhanced by cooking
and mastication
STOMACH
 No carbohydrate digestion in stomach
 Salivary amylase on reaching stomach
get inactivated by acidic pH
Cannot act on raw food
Acts on boiled food
Starch
glycogen
α- limit dextrin
Malto-oligosaccharides
Malto-triose
Maltose
isomaltose

6. INTESTINE
 Major carbohydrate digestion occurs in
duodenum catalyzed by Pancreatic
amylase secreted by pancreas
Pancreatic amylase
- more potent in its activity than salivary
amylase
- can act both on raw and boiled food
- specifically act on α-1,4 glycosidic bonds

8. intestinal epithelial cells
in small intestine
(enterocytes) absorb only
monosaccharides
• Glucose
• Galactose
• Fructose

9. GLUCOSE & GALACTOSE
 Glucose and galactose are absorbed across apical membrane of enterocytes by
secondary active transport
 Glucose and galactose move from intestinal lumen into enterocytes via Na+- glucose
cotransporter (SGLT1)
 SGLT in apical membrane of enterocytes
 Glucose and galactose move up (or against) electrochemical gradient ("uphill")
Na+ moves down electrochemical gradient ("downhill") provides energy for uphill
movement of glucose and galactose
 Na+-K+ ATPase in basolateral membrane of enterocytes establishes and maintains
Na+ gradient across apical membrane responsible for providing energy for uphill
movement of glucose and galactose
 Glucose and galactose move from enterocytes across basolateral membrane to
bloodstream by facilitated diffusion (GLUT2)

10. FRUCTOSE
 Fructose is absorbed across apical membrane of enterocytes by facilitated diffusion
(GLUT5)
 Unlike glucose and galactose, fructose cannot be absorbed against electrochemical
gradient ("uphill")
 Fructose moves from enterocytes across basolateral membrane to bloodstream by
facilitated diffusion (GLUT2)