Digestion and absorption of carbohydrates

The carbohydrates in the diet are broken down by the enzymes on the mouth, pancreas and intestinal epithelium.

Digestion resumes in the small intestine where more polysaccharide splitting enzymes from the pancreas break the carbohydrate down completely into disaccharides. The enzyme released through the common bile duct into the small intestine.

Then enzymes on the surface of the cells of the small intestine break these into simple sugars or monosaccharaides.  Maltose is split into two glucose molecules; lactose is split into one glucose and one galactose; and sucrose into one glucose and one fructose.

However the great majority of carbohydrates in human meal are digested and absorbed as glucose, if a blood glucose levels are measured before such a meal and at half hourly intervals thereafter, it would show a rise in blood glucose, peaking at about the half hour mark and returning to fasting levels almost as quickly.

If a person were to abstain from carbohydrates for considerable periods say a week, the blood glucose levels would still be normal in spite of a minimal or zero intake.

The active absorption of glucose across the intestinal mucosa is thought to be by phosphorylation in the mucosal cell.

The body’s capacity to maintain blood glucose within specific limits is achieved by a variety of hormones, the two most important of which are insulin and glucagon. Both are secreted by the pancreas into bloodstream, as required.

When the blood glucose level arises, the body adjusts by storing the excess. The frost organ to detect the excess glucose is the pancreas, which releases the hormone insulin in response.
Digestion and absorption of carbohydrates

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