2t Bricks digestion 3.3 + 3.4

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• Middelbare school
• havo, vwo
• Leerjaar 2

Digestion

Bricks 3.3 + 3.4

Digestion

Digestion: Breakdown of food molecules into small food molecules 

When food is digested it is absorbed  

Big vs. Small

Big molecules -> Insoluble can not get through the gut wall

Small molecules -> Soluble can get through the gut wall

Fases of digestion. Put them in the right order.

1

2

3

4

digestion

ingestion

absorption

elimination

FASES OF DIGESTION:

• INGESTION
• CHEMICAL AND MECHANICAL DIGESTION
• ABSORPTION
• ELIMINATION

Ingestion

Mechanical digestion

Chemical digestion

MOVING THE FOOD INTO YOUR MOUTH

BREAKING THE FOOD INTO SMALLER PIECES.

THIS IS DONE BY YOUR TEETH

BREAKING THE FOOD INTO EVEN SMALLER PIECES.

USING ENZYMES TO BREAK DOWN THE FOOD MOLECULES. 

CHEMICAL DIGESTION:

• BREAKING THE FOOD INTO EVEN SMALLER MOLECULES.
• USING ENZYMES TO BREAK DOWN THE FOOD MOLECULES. 

Chemical digestion

Enzymes: Important chemicals

duodenum

salivary gland

liver

pancreas

gall bladder

small intestine

large intestine

stomach

oesophagus

rectum

appendix

pancreatic duct

anus

Chemical digestion Step 1: mouth

• starts in: the mouth 
• the enzyme: amylase (a carbohydrase)
• the liquid: saliva 
• the nutrient: carbohydrates
• the products: glucose 

The enzymes in your saliva start breaking down the carbohydrate molecules into glucose.

Down the tube!

Oesophagus

Peristalsis: moving food down your oesaphagus (gullet)

Why is your stomach rumbling? 

-peristalsis, muscle activity

- mechanical digestion

-Empty stomach and intestines make a louder sound!

Step 2: stomach

Digestive juices are added

• Proteases -> digestion proteins -> amino acids
• Hydrochloric acid -> acid PH, best for the enzymes + acidic environment also kills germs
• Rennin (only babies) makes milk solid, stays in the stomach longer

Step 3: duodenum

Step 3: duodenum

2 important liquids added in the first part (the duodenum)

• Pancreatic juice (contains enzymes: carbohydrases, proteases and lipases)
• Bile made by the liver, stored in the gall bladder

    --> Bile is alkaline neutralises acid from the stomach
    --> Bile emulsifies fats, increases surface area of fats, makes it easier for lipase enzymes to act upon

Bile is made by the:

1. liver
2. gall bladder
3. pancreas
4. duodenum

The food molecules in the duodenum are broken down by enzymes in

1. bile
2. pancreatic juice
3. pancreatic juice and bile

Is pancreatic juice a digestive juice? And what about bile?

1. Both are digestive juices
2. Only pancreatic juice is a digestive juice
3. Only bile is a digestive juice

Step 4: small intestine

Intestinal juice (carbohydrases, proteases, lipases) Complete digestion of food, made by the wall of the small intestine

Amylase is an example of a

1. Carbohydrase
2. Lipase
3. Protease

After breaking down of proteins you get:

1. glucose
2. amino acids
3. fatty acids
4. glycerol

After breaking down fats you get:

The environment of the stomach is

1. Acidic
2. Alkaline
3. Neutral