Digestion

Your digestive system is huge! Roughly 9 meters in fact.

However it doesn't all work the same. We can break the actions of the digestive system up into 2 parts.

Physical (Mechanical) Digestion and Chemical Digestion.

Mechanical Digestion is the physical breakdown of your food.

Your teeth do a lot of the physical digestion. Cutting and Grinding the food into smaller bits.

Your stomach also helps by churning and moving the food around.

Chemical Digestion is slightly more complicated. Your stomach is filled with strong acids and juices which break down food and anything entering your stomach.

Not just in your stomach but also in your mouth and in fact all through out your body are tiny little workers called enzymes.

So what are these enzymes?

Quick Questions

1. What are the two types of digestion your body uses?

2. Give 2 examples of each type of Digestion

3. What is found in the stomach?

Enzymes

Perhaps the most important biological molecule in any animal. They are small proteins which break down large molecules into small molecules.

Saliva in your mouth contain enzymes which break down starch into smaller pieces.

Enzymes in your stomach and small intestine breakdown proteins and lipids into smaller molecules.

They are known as Biological catalysts. This means the speed up reactions without being used up.

Carbohydrase is an enzyme (most enzymes will end in ‘ase’). It breaks down carbohydrates into sugar molecules.

We find this enzyme in your mouth, stomach and small intestine.

Protease is an enzyme which breaks down proteins into amino acids.

It is found in the stomach and small intestine.

Lipase breaks down lipids into fatty acids and glycerol molecules.

He lives in the small intestine, and is helped by bile, produced by the liver.

So to recap - Enzymes are:

Biological catalysts (speed up reactions)

Re-usable

Made of proteins

Important for breaking down or building up molecules.

Quick Questions

1. What are 3 properties of enzymes

2. Give two examples of enzymes and what they break down

Bacteria.

Contraire to popular belief most bacteria out there is actually helpful. Its only a small handful of bacteria which causes us harm and pain.

Your large intestine contains lots of good bacteria. They live on the fibre in your diet and produce important vitamins (vitamin K).

You can find these bacteria in yogurt and other pro-botic foods.

Questions

Short Answer Questions

1. Copy and Complete the sentence below

Carbohydrates are broken down into sugar by the enzyme _________ . _______ Are broken down into _______ by the enzyme protease. Lipids are broken down _________ and ______ by the enzyme _______.

2. Define and enzyme and explain its role in the body.

3. Why is yogurt important in a balanced diet.

4. Explain how enzyme affect the rate of digestion

5. How does bacteria improve the health of an individual.

Extension

6. Explain what would happen to your body if you went on a ‘detox’ and removed all fibre, protein and fat from your diet and only drank lemon juice.

7. Create a pamphlet to explain the benefits of bacteria to the ordinary person

8. Make a visual summary of the ideas on this page, comparing the roles of enzymes and bacteria in digestion.