2.2 digestive system

• Biologie
• Middelbare school
• havo, vwo
• Leerjaar 2

Welcome- 2EH

• Please take your seat
• Get you notebook , book and pen.
• Take out your coat and wait quietly for the Assignment in the next dia. 

Start activity - 10 min (ZS)

Get your book.

Complete ex. 10 & 11

Done?

Begin reading basic 2.2 : the digestive system 

Goals 

• Can describe the functions of digestion, digestive juices and enzymes.
  
• Can list the parts of your dentition and their functions.
  
• Can describe the function of peristalsis and how it works.

The digestive system

During digestion, larger nutrient molecules are broken into smaller digestion products in two ways:

1. Breakdown by chewing

2. Converting the nutrients using digestive juices

Your teeth

The food you eat needs to go through your whole intestinal tract (about 15 meters!). 

So the food needs to get smooth, whole and wet.

All that happens in your mouth. 

You chew it and your salivary glands add saliva. 

Teeth

• INCISORS
• CANINES
• PREMOLARS
• MOLARS

• CHILD HAS 20
• ADULT HAS 32

Your teeth

Besides that, by chewing your food you create more surface. This means more space for digestive juices to attach to and digest food more easily. This is a way of mechanical digestion. 

CHEMICAL DIGESTION:

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

ENZYMES

• Salivary glands: amylase
• Stomach wall: protease (pepsin)
• Pancreas: protease, amylase, lipase
• Small intestines: peptidase, maltase, nuclease

Enzymes

Chemical digestion

Enzymes: Important chemicals

Chemical digestion Step 1

• 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!

In your 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

small           intestine

In your small intestine

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

• Pancreatic juice (carbohydrase, proteases and lipases)
• Bile from the liver, stored in the gall bladder
• Bile is alkaline neutralizes acid from the stomach
• Bile emulsifies fats, increases surface area of fats lipase enzymes to act upon

In your small intestine

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

To do:

Read 2.2 - The digestive system 

Complete ex. 1 - 3  & 5-9

Done? 

Login to the class lesson up folder and complete the lesson

Practice the flash cards 

1

2

3

4

5

6

7

8

heart

large intestine

small intestine

stomach

lung

liver

brain

kidney

During the break down of proteins you get:

1. glucose
2. amino acids
3. fatty acids

The environment of the stomach is

1. Acidic
2. Alkaline

Amylase is an example of a

1. Carbohydrase
2. Lipase
3. Protease

Which enzyme breaks down carbohydrates in the mouth?

1. Maltase
2. Amylase
3. Protease
4. Lipase

What enzyme aids in the breakdown of proteins in the stomach?

1. Lactase
2. Amylase
3. Pepsin
4. Sucrase

Which enzyme assists in the digestion of fats in the small intestine?

1. Amylase
2. Pepsin
3. Lipase
4. Maltase