THE DIGESTIVE SYSTEM
Vocabulary: absorption, anus, chyme, digestive system, faeces, large intestine, liver, oesophagus, pancreas, pharynx, salivary glands, small intestine.
NUTRITION
Vocabulary: carbohydrates, diet, fats, fibre, minerals,
nutrition, proteins, vitamins, water
1. The digestive system
We need to eat. Food gives us the energy which we require for our daily activities. It also gives us the substances which we need to grow.
The digestive system converts the food we eat into nutrients which our body can absorb.
It carries out three important functions: digestion, absorption and the elimination of waste.
2. Digestion
• First, food is chewed in the mouth, and mixed with saliva produced by the salivary glands.
Gradually, a mass of chewed, soft food is formed.
• Then, this food moves down the pharynx and the oesophagus, and passes into the stomach.
• Next, it mixes with gastric juices in the stomach. This produces a thick liquid called chyme.
• Finally, the chyme leaves the stomach and reaches the small intestine.It mixes with juices from the intestine, the pancreas and the liver. All the substances which we require have now been separated.
3. Absorption
In the small intestine, the substances which we need are absorbed into the blood.
4. Elimination of waste
The chyle loses its nutritional value as it passes through the small intestine.
Only undigested substances, like fibre, remain and move to the large intestine.
The large intestine removes water from these substances, and forms solid waste called faeces.
This is expelled through the anus.
