3. Mechanical Digestion
Chewing, also known as mastication, crumbles the carbohydrate
foods into smaller and smaller pieces to form bolus.
Chemical Digestion
Salivary glands in oral cavity secrets saliva.
Saliva contains enzyme salivary amylase/ptyalin.
Salivary amylase hydrolyses starch into maltose and dextrin at pH
of 6.8 to 7.
Only about 5% starch are broken down in mouth.
4. Mechanical Digestion
The strong peristaltic contractions of the stomach mix the carbohydrates
into the more uniform mixture of chyme.
Chemical Digestion
The action of ptyalin continues only inside bolus.
About 30-40% of dietary starch is digested before bolus is broken down
and acidified.
The action of ptyalin is blocked by acidic nature of stomach(pH 1.5).
Further breakdown of carbohydrates takes place when the chyme is passed
down to the small intestine.
5. Mechanical Digestion
There is no mechanical digestion in small intestine.
Chemical Digestion
The pancreas releases pancreatic juice through a duct.
Pancreatic juice contains the enzyme, pancreatic amylase.
Enzymes are also secreted by the intestinal cells that line the
villi.
6. Hydrolyze oligo- and polysaccharides into
monosaccharide as follow:
o Starch pancreatic amylase Maltose + Isomaltose
o Maltose maltase Glucose +Glucose
o Isomaltose isomaltase Glucose + Dextrin
o Dextrin dextrinase Glucose
o Sucrose sucrase Glucose + Fructose
o Lactose lactase Glucose + Galactose
7. Certain carbohydrate like cellulose are undigested by human
due to lack of enzymes like cellulase.
But ,it provides fibers for absorption of water into the large
intestine ,expand the muscle walls and trigger the muscle
contractions for egestion.
Cure for constipation.
8. Digested food from
alimentary canal to
blood stream.
Monosaccharide is absorbed
in small intestine.
Sodium Glucose Transport
Protein(SGLT) in membrane
helps absorb glucose and
galactose.
Fructose absorbed is
converted to glucose inside
cell.
