THE DIGESTIVE SYSTEM

We need to eat. Food gives us 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.

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.

ABSORPTION

In the small intestine, the substances which we need are absorbed into the blood.

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.

DIET

The food which someone normally eats over a period of time is called their diet. For good, healthy nutrition, our diet must be complete and balanced.

A complete diet includes nutrients from all the food groups.

A balanced diet includes the right amount of each nutrient.

OTHER NUTRITIVE SUBSTANCES

Vitamins and minerals are essential for our bodies to function well. Fruits and vegetables are good sources,but minerals and vitamins are also found in other foods. Milk give us calcium for our bones.

Water.Most of our body is made up of water, so it is essential. We drink water, and our body also obtains water from food.

Fibre helps food to move through the digestive system. It is found in fruits, vegetables and whole-grains.

NUTRIENTS

Nutrients are the substances which our body needs to survive, grow and repair itself. Nutrients also give us energy.

Carbohydrates give us energy.There are two types of carbohydrate. Sugars are in foods which taste sweet.Starches are in bread, potatoes and legumes.

Fats also give us energy. We get some fats, such as butter, from animals. We get other fats, such as olive oil, from plants.

Proteins help our body to grow and repair itself. Meat, fish and legumes are good sources of protein.