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The Digestive System

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Digestive functions

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Breaking down substances

The mechanical breakdown of food into smaller pieces is called physical digestion.

This process occurs: by chewing food in the mouth by squeezing in the stomach.

What is the purpose of physical digestion? Smaller pieces of food will pass more easily through

the alimentary canal. Smaller pieces of food will provide a greater surface

area for enzymes to break down the substance further.

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From the mouth to the stomach

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From the small intestine to the blood

Physical digestion continues in the stomach as it squeezes its contents into the small intestine.

Here, the digested particles are absorbed into the blood to be taken elsewhere in the body.

Only smaller molecules, such as glucose, are able to diffuse from the small intestine, through the villi, and into the blood, moving from higher to lower concentration.

glucose

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Enzymes in the body

Enzymes catalyze thousands of reactions that need to take place in order to maintain life. What are some of these reactions?

digestion.

respiration

protein synthesis

Digestive enzymes break down large food molecules into smaller molecules so they can be absorbed into the blood. This is called chemical digestion.

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Enzymes of digestion

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Further breakdown of starch

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