The digestive system

 What body parts form the digestive system?

Most of the digestive system is formed by the digestive tract. This is a long tube that goes down the neck and torso.

The digestive system has other organs and glands which help digestion.

• Saliva, which helps to soften food, is produced by the salivary glands.

• The liver releases a liquid called bile into the smaller intestines.

• The pancreas releases pancreatic juice into the small intestine.

How do we digest food?

The purpose of digestion is to break down food into nutrients that can be absorbed, to take in water and to expel waste.

1 In the mouth and oesophagus.

The teeth tear up food and the tongue mixes the food with saliva. When it has formed a ball, or bolus, we swallow it. The bolus travels down the pharynx and oesophagus to the stomach. The epiglottis stops the bolus from entering the respiratory tract.

The teeth tear up food and the tongue mixes the food with saliva

The bolus travels down the pharynx and oesophagus to the stomach.

Epiglottis

2 In the stomach

The stomach walls secrete gastric juices that mix with the bolus. The gastric juices break down the nutrients in the bolus to form a substance called chyme.

3 In the small intestine

The small intestine secretes intestinal juices. Along with pancreatic juice and bile, they mix with the chyme to form a substance called chyle. This process completes the digestion of food. The nutrients are absorbed by the blood capillaries around the small intestine.

4 In the large intestine

Food that that is not digested and water travel to the large intestine. Water is absorbed and faeces are formed from the food. Faeces are expelled through the anus.

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