1. Digestion & absorption of carbohydrates
Digestion of carbohydrates start by
pancreatic α-amylase which breakdown
starch into maltose, limit dextrin, and
small quantity of glucose. α-amylase
catalysis is the cleavage of α-1,4
glycosidic linkage. The role of salivary
amylase in digestion of starch is
negligible. The limit dextrins are attack
by isomaltase which cleave α-1,6
glycosidic linkage.

2. • Digestion of disaccharides not occur in
intestinal lumen but rather in brush border of
microvilli.
• Absorption of monosaccharide:
brush border has two functions: digestive
function & absorptive function.
disaccharidase (maltase for maltose , sucrase
for sucrose , lactase for lactose) convert
disaccharides into its corresponding
monosaccharide.

3. • The products carbohydrates Digestion are
absorbed into the blood of the portal venous
system in the form of monosaccharides chiefly
the hexoses & pentose sugar.
glucose & galactose are absorbed by Na-
dependent active transport while fructose is
absorbed by Na- independent passive transport .
cells divided into two types of cells based on
whether or not insulin is requires for transport of
glucose into the cell:

4. 1-Insulin-dependent cells:
these include muscle & adipose cells.
“ cardiac muscle “
2-Insulin-independent cells:
these include brain , liver , erythrocytes ,
kidney , and intestine.

5. Glycogen metabolism:
Glycogen is considered the principle storage
form of glucose & its found mainly in the liver,
& muscle with kidney & intestine adding
minor storage sites.
1- Glycogen synthesis:

6. Glycolysis:
Glycolysis is a pathway in which the glucose
molecule ‘which has 6 carbon atoms’ is
enzymatically degraded into two molecules of
pyruvate ‘which has 3 carbon atoms’.
the enzymes of glycolysis are present in cell
cytosol.