The digestive system

The stages of digestion

Home TeachersDigestive systemThe stages of digestionThe small intestine

The duodenum is the first segment of the small intestine. Within the duodenum, nutrients are simplified by the action:

  • of  pancreatic juices originating in the pancreas,
  • of bile originating in the liver and stored in the gall bladder.

The nutrients are then absorbed by the organism. The small intestine is covered with millions of folds, or villi, increasing the surface for absorption.

The nutrients pass into our blood vessels, which carry them into the cells of our bodies.
 

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The small intestine

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THE DUODENUM

The duodenum is the first segment of the small intestine. It is an important segment because it receives pancreatic juice and bile at the same time.

Pancreatic juice comes from the pancreas and contains several digestive enzymes, mainly pancreatic amylase, chymotrypsin, trypsin and lipase. Pancreatic amylase continues to transform complex carbohydrates such as starch and glycogen. These substances are mainly transformed into glucose and maltose.

Protein transformation starts with pepsin in the stomach and continues in the duodenum through the action of several enzymes, namely trypsin and chymotrypsin. These enzymes break down small chains of amino acids into small peptides and amino acids.

Lipases are enzymes that transform lipids into fatty acids and glycerol.

Bile emulsifies lipids to help lipases do their job. An emulsion is a mixture of two liquids that normally cannot be mixed together, such as oil and water. A third ingredient, called an ‘emulsifier’, stabilises this mixture. The emulsion allows for the formation and coating of micro-droplets of fat to prevent them from sticking together.

THE PANCREAS IN DIGESTIX

The pancreas is an important element of the digestive system and this is also true in DIGESTIX.
Pancreatic juice transforms carbohydrates into glucose and maltose. Just like gastric juice, it also transforms proteins and lipids. So, in DIGESTIX, the pancreas has three specific targets.

THE LIVER IN DIGESTIX

Bile comes from the liver. It has a yellowish colour and is stored in the gall bladder.

The liver is another digestive piece in DIGESTIX. It has an impact on the transformation of lipids. The game mentions the gall bladder together with the liver, but keep in mind that the gall bladder only stores bile; it does not secrete any enzymes.

THE ABSORPTION OF NUTRIENTS

Nutrients travel through the small intestine with the help of peristaltic waves, which are the same type of contractions found in the oesophagus and stomach.

Once in the small intestine, nutrients have been sufficiently transformed to allow them to cross the intestinal wall and be absorbed by the body. The small intestine is lined with millions of folds, called villi. These folds greatly increase the absorption surface.

Nutrients then move into the blood, which brings them to the body’s cells where they will be used.

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