Functions of the Digestive System
Biology: Cambridge International GCSE Supplement, topic 7.2.2
Digestion
These are the roles of different parts of the digestive system during digestion:
Mouth
- Food and drink is taken into the body through the mouth.
- The teeth break up food into small pieces.
- Enzymes in the saliva (spit) start breaking down starch.
Stomach
- The stomach contracts to break down food particles into even smaller pieces.
- Proteases start breaking down proteins in the stomach.
- Stomach acid kills harmful microorganisms.
Liver
- The liver produces bile, which is then stored in the gall bladder.
- Bile emulsifies fats in digestion.
Pancreas
- The pancreas secretes digestive enzymes into the small intestine. These enzymes are:
- Proteases
- Carbohydrases
- Lipases
Small intestine
- Absorption of food involves the movement of small food molecules through the wall of the small intestine into the blood.
- The walls of the small intestine are covered in structures called villi which provide a large surface area for absorption.
Large intestine
- Water is absorbed through the walls of the large intestine into the blood.
- After water has been absorbed through the large intestine, undigested food leaves the body as faeces (poo) through the anus.
Test yourself on Functions of the Digestive System
Which of these is not a function of the stomach during digestion?
Which enzymes are secreted by the pancreas?