2.2 - the digestive system

• Biologie
• Middelbare school
• vwo
• Leerjaar 2

The digestive system

Today's lesson

1 What is digestion?

2 Discuss chewing

3 What are digestive juices?

4 Explain peristalsis

What is digestion?

Fig. 1: digestive system 

Contains the intestinal tract: 

long piece of tubing from mouth 

to anus

Digestion continued

• What is the function of the digestive system?

Digestion continued

• what is the function of the digestive system?
• Nutrients from food absorbed into bloodstream

Digestion continued

• What can be directly absorbed into the blood?

Digestion continued

• What can be directly absorbed into the blood?
• Glucose, minerals, water, vitamins

Digestion continued

• What nutrients are missing?

Digestion continued

• What nutrients are missing?
• Proteins, carbohydrates and fats

THESE NEED TO BE DIGESTED FIRST

How is food digested?

• Digested: break down into small pieces
• 2 types of digestion: Mechanical and Chemical digestion
• Mechanical: chewing
• Function: break the food into little pieces so that the surface area is larger.

Exercise surface area to volume ratio

Chemical Digestion

• Breaking food into even smaller molecules
• How? 
• Use digestive juices made in the digestive glands
• Digestive juices contain enzymes.

Peristalsis

Food moves through lots of tubes : intestinal tract

• Oesophagus
• Duodenum
• Small and large intestines

peristalsis = muscle movements that push food through the intestinal tract

Peristalsis

HW

do the exercises of bs 2 - The digestion system

work on your summary

read bs 3