The digestive system

The stages of digestion

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The small intestine

What happens in the duodenum?

The duodenum, the first part of the small intestine, receives pancreatic juice and bile.

Pancreatic juice is produced by the pancreas and contains several enzymes that are very useful for digestion.

Pancreatic amylase continues to transform complex carbohydrates, such as starch and glycogen into glucose and maltose.

Trypsin and chymotrypsin continue the transformation of proteins that started in the stomach and break down the short chains of amino acids into small peptides and amino acids.

Lipases transform lipids into fatty acids and glycerol.

Bile, produced by the liver, forms an emulsion with the lipids so the tiny droplets of fat make the lipases’ work easier.

How are nutrients absorbed?

The transformed nutrients pass through the wall of the small intestine, which is lined with millions of folds called villi. These folds increase the absorption surface.

The nutrients pass into the blood vessels, which take them to all the body’s cells to help them carry out their specific functions.

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