NUTRITION

Our bodies need energy to work. The energy we receive in the form of food and drink is processed by the digestive system. The respiratory system extracts oxygen from the atmosphere and uses it to convert the nutrients into energy. The circulatory system then transports this energy to different parts of the body. Finally, the excretory system gets rid of unwanted or toxic substances. The different systems all work in harmony to keep us healthy.

1- The digestive system

Nutrients are the substances that animals need in order to live and grow. The digestive system is the group of organs in the body that extract nutrients from food and expel undigested waste.

     

  

Digestion

1- We produce saliva in our mouths  that helps the teeth to crush food as we chew it .

2-The tongue shapes the food into a ball that we swallow and passes into the oesophagus  , which is a tube that links the throat with the stomach. The epiglottis is a special  part that prevents food from going down the windpipe and into the lungs. 

3- The stomach is to break down food by using its strong muscular walls and excreting gastric juices which mix with the food.

4- The food is dissolved into a liquid and passes into the small intestine. Here it mixes with bile,  produced by the liver, and pancreatic juices, produced by the pancreas. The food mixture is broken down into proteins, carbohydrates, vitamins, minerals and fats. These nutrients pass through the walls of the small intestine and are absorbed into the blood.

5-The waste that our body does not need passes to the large intestine. Here, water from this waste is absorbed into the blood. The solid waste leaves our body through the anus