Metabolism
Metabolism of carbohydrates and lipids
What is Digestion
A physical and chemical protein in which large food molecules break down into simple
absorbance compound
Digestion and absorption of carbohydrates
● • Digestion of carbohydrates begins in the mouth where salivary amylase
(ptyalin) breaks starch into maltose and small dextrins.
● • In the stomach, carbohydrate digestion temporarily stops because acidic gastric
juice inactivates salivary amylase.
● • In the small intestine, pancreatic amylase continues digestion and converts
remaining starch into maltose, maltotriose, and dextrins.
● • Enzymes present on the intestinal brush border such as maltase, sucrase, and
lactase convert disaccharides into monosaccharides.
● • Maltase converts maltose into two molecules of glucose.
● • Sucrase converts sucrose into glucose and fructose.
● • Lactase converts lactose into glucose and galactose.
● • Only monosaccharides (glucose, fructose, galactose) are absorbable forms of
carbohydrates.
● • Glucose and galactose are absorbed through intestinal epithelial cells by active
transport using sodium-glucose co-transport mechanism.
● • Fructose is absorbed by facilitated diffusion without the use of energy.
● • Monosaccharides pass from intestinal cells into blood capillaries of the villi.
● • Absorbed monosaccharides are transported to the liver through the hepatic
portal vein.
, ● • In the liver, excess glucose is converted into glycogen for storage or released
into blood to maintain normal blood glucose level.
Absorption of carbohydrates
1. Carbohydrates are absorbed in the small intestine mainly in the jejunum.
2. • Only monosaccharides are absorbed; these include glucose, fructose, and
galactose.
3. • Glucose is absorbed by active transport with the help of sodium ions through
the intestinal epithelial cells.
4. • Galactose is absorbed by the same sodium-dependent active transport
mechanism.
5. • Fructose is absorbed by facilitated diffusion without the use of energy.
6. • Absorption occurs through the epithelial lining of intestinal villi.
7. • Monosaccharides move from intestinal cells into blood capillaries.
8. • Blood capillaries carry absorbed sugars to the liver through the hepatic portal
vein.
9. • In the liver, monosaccharides are converted into glucose or stored as glycogen.
Metabolism of carbohydrates and lipids
What is Digestion
A physical and chemical protein in which large food molecules break down into simple
absorbance compound
Digestion and absorption of carbohydrates
● • Digestion of carbohydrates begins in the mouth where salivary amylase
(ptyalin) breaks starch into maltose and small dextrins.
● • In the stomach, carbohydrate digestion temporarily stops because acidic gastric
juice inactivates salivary amylase.
● • In the small intestine, pancreatic amylase continues digestion and converts
remaining starch into maltose, maltotriose, and dextrins.
● • Enzymes present on the intestinal brush border such as maltase, sucrase, and
lactase convert disaccharides into monosaccharides.
● • Maltase converts maltose into two molecules of glucose.
● • Sucrase converts sucrose into glucose and fructose.
● • Lactase converts lactose into glucose and galactose.
● • Only monosaccharides (glucose, fructose, galactose) are absorbable forms of
carbohydrates.
● • Glucose and galactose are absorbed through intestinal epithelial cells by active
transport using sodium-glucose co-transport mechanism.
● • Fructose is absorbed by facilitated diffusion without the use of energy.
● • Monosaccharides pass from intestinal cells into blood capillaries of the villi.
● • Absorbed monosaccharides are transported to the liver through the hepatic
portal vein.
, ● • In the liver, excess glucose is converted into glycogen for storage or released
into blood to maintain normal blood glucose level.
Absorption of carbohydrates
1. Carbohydrates are absorbed in the small intestine mainly in the jejunum.
2. • Only monosaccharides are absorbed; these include glucose, fructose, and
galactose.
3. • Glucose is absorbed by active transport with the help of sodium ions through
the intestinal epithelial cells.
4. • Galactose is absorbed by the same sodium-dependent active transport
mechanism.
5. • Fructose is absorbed by facilitated diffusion without the use of energy.
6. • Absorption occurs through the epithelial lining of intestinal villi.
7. • Monosaccharides move from intestinal cells into blood capillaries.
8. • Blood capillaries carry absorbed sugars to the liver through the hepatic portal
vein.
9. • In the liver, monosaccharides are converted into glucose or stored as glycogen.
