2.2 - the digestive system

• Biologie
• Middelbare school
• vwo
• Leerjaar 2

start task 'digestive system'

1. copy these learning objectives to your zuidschrift:

- You can describe the functions of digestion, digestive juices and enzymes.

- You can describe the function of peristalsis and how it works.

2. join this LessonUp.

Today's lesson

1. review: nutrients                            3

2. video + theory: digestion          25

3. assignments                                   10 

4. lesson end                                         2

homework: +/- 30 min.

HW Review

List the 6 groups of nutrients
(try to do this without looking in your (note)book)

theory

- what is digestion?

- chewing

- peristaltis

Digestive system

Fig. 1 pg. 97: digestive system 

Contains the intestinal tract: 

long piece of tubing from mouth 

to anus

food --> cells

• The food we eat contains important nutrients that our body needs.
• To get these nutrients to our cells, they must first enter our blood.
• Some nutrients like glucose, minerals, and vitamins are already small enough to be absorbed from the intestines into the blood.
• Other nutrients need to be broken down by digestion before they can be absorbed.

what for?

fuel

building material

reserves

protection

Digestion

Digestion: Breakdown of nutrients from food into small molecules that can be absorbed (opgenomen) from the intestines into the blood.

Big vs. Small

Big molecules ->  can not get through the gut wall

Small molecules ->  can get through the gut wall

Fases of digestion. Put them in the right order.

1

2

3

4

digestion

ingestion

absorption

egestion

Egestion

The process of removing undigested food from the body.

Parts of the food that can't be used by the body are expelled as waste (on the toilet!)

DIGESTION:

Digestion can occur mechanically (through movement) or chemically (by enzymes!).

Chewing!

Increases the surface area of food. 

--> helps chemical digestion to go faster.

mechanical digestion

Chemical Digestion

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

chemical digestion

mechanical digestion

enzymes

chewing

to help swallow food more easily

surface area enlargement

digestive juices 

in the mouth

e.g. in stomach,  intestines

in the mouth

Peristalsis

Alternate contraction and relaxation of  circular + longitudinal muscles through the digestive tract

Peritalsis & peristaltic movement

(homework) assignments

1. translate organ names (fig 1 pg 97) 

    into Dutch

2. do asg. 1 t/m 3, 5 , 6 and 8 (pg. 100-103)

use text pg. 97-100