2.2 - the digestive system

• Biologie
• Middelbare school
• vwo
• Leerjaar 2

Welcome everyone 

 Think about...

• Take off your coat, hat/cap off.
• Mobile in the phone bag (on silent).
• Book (laptop) + notebook, pen on the table. Bag on the floor.
• Sit in your own place.
• You can eat and drink in the canteen.
• 5 minutes.

Schedule 

• Repetition                              5 min.
• Explanation 2.2/2.3           10min.
• Doing a Assignments       10 min    
• Explanation 2.2/2.3 10min.
• Finish Posters   
• Closing                                     5 min. 

HW Review

Nutriens: usable components in food

Dietary fibre: are indigestible parts of the plants 

vegetable produces

Animal products

Foodstuffs

Function of Nutrients

• Building blocks: grow/develop/repair
• Fuels/Energy-rich: by respiration in cells to provide energy
• protection: to stay healty  

6 groups of nutrition's

carbohydrates

fats

proteins

minerals

vitamins

Water

Learning goals 

At the end of the lesson..

• You can describe the functions of digestion, digestive juices and enzymes.
• You can describe the function of peristalsis and how it works.
• You can list the functions and characteristics of the parts of the digestive system.

What is digestion?

Fig. 1: digestive system 

Contains the intestinal tract: 

long piece of tubing from mouth 

to anus

The digestive system

Digestion continued

• Nutrients from food absorbed into bloodstream
• What can be absorbed into the blood?                                               - Glucose, minerals, water vitamins
• What should be digested first?                                                                 - Proteins, carbohydrates and fats

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.

Enzymes

the oral cavity, pharynx and oesophagus

what are the names of the glands together? what do they do?

• salvary glands produces salvia: containing water, enzymes and mucus

Chemical Digestion

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

Make assignments 

Make assignment 1,2,3 and 5  of 2.2 

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

Peritalsis & peristaltic movement

stomach

• circular + longitudinal muscle for constantly movement
• pyloric sphincter is a circular muscle who close off the stomach
• the gastric gland produces gastric juices: containing: water, enzymes to digest proteins and hydrochloric acid to kill germs  

• liver produces bile (gal)
• bile is temporarily stored in the gall bladder
• bile passes through the bile duct when necessary
• bile emulsifies fats to make it easier for enzymes to digest.

• The wall of the intestines contains intestinal glands. They produce intestinal juice.
• various enzymes digest carbohydrates, fats and proteins
• the wall is convoluted, the intestinal folds in turn have protrusions called intestinal villi. 
  
• the wall of the intestinal villi is very thin. nutrients can pass easily 

• direct after the small intestines the caecum. (blinde darm). 
• the protrusion is called the appendix.
• inflamed in appendicitis; the appendix will be surgically removed. 
• In the large intestine water is extracted from the pulp. 
• If not -> Diarrhea
• Only undigested residues left over
• Bacteria are able to digest some cellulose and turn is into glucose
• glucose is absorbed into the bloodstream.  
  

HW

Read 2.2 - The digestion system

 Qs 1 t/m 3, 5 , 6,7 and 8

Done? finish 2.1: 1 until 9 or start with 2.3