Digestion & absorption of carbohydrates

Carbohydrates

Human diet contains 3 types of carbohydrates

Polysaccharides

Glycogen,  amylase and amylopectin

Glycogen -- non vegetarian diet

Amylase and amylopectin --- vegetarian sources

Disaccharides

Sucrose

which is called cane sugar

Glucose   +   Fructose

Lactose –available in milk

Glucose  +   Galactose

Monosaccharide

Glucose ,&  Fructose  

Digestion

Mouth

Saliva---Amylolytic enzymes

Polysaccharides –cooked starch

Stomach

Contains weak amylase

Digestion of carbohydrates

Intestine

Pancreatic amylase—polysaccharides---Disaccharides (dextrin and maltose)

Sucrase --- sucrose---glucose + fructose

Maltase --- maltose----glucose

Lactase ----Lactose---glucose  +  galactose

Dextrinase---dextrin, maltose----glucose

Absorption carbohydrates

Glucose and galactose

These are transported from  the intestinal lumen into the cells by Na dependent co transport in the luminal membrane

This sugar is transported uphill and Na is transported downhill

These are then transported from cell to blood by diffusion

Sodium ion moves laterally into the intercellular space

From here , it is transported into blood by active transport

In this process the energy is utilized which is liberated by breakdown of ATP

Fructose

It is absorbed into the blood by means of facilitated diffusion

Some molecules of fructose are converted into glucose

The glucose is absorbed

DIGESTION OF CARBOHYDRATES

AREA	JUICE	ENZYME	SUBSTRATE	END POINT
MOUTH	SALIVA	SALIVARY AMYLASE	POLYSACCHARIDES COOKED STARCH	DISACCHARIDES DEXTRIN    & MALTOSE
STOMACH	GASTRIC JUICE	GASTRIC AMYLASE	WEAK AMYLASE	ACTION  IS NEGLIGIBLE
	PANCREATIC JUICE	PANCREATIC AMYLASE	POLYSACCHARIDES	DISACCHARIDES DEXTRIN, MALTOSE MALTRIOSE
SMALL INTESTINE	SUCCUS ENTERICUS	SUCRASE MALTASE LACTSE DEXTRINASE	SUCROSE MALTOSE LACTOSE DEXTRINE MALT OSE MALTRIOSE	GLUCOSE & FRUCTOSE GLUCOSE GLUCOSE & GALACTOSE GLUCOSSE