CBSE Class 7 Answered

The breakdown of complex components of food such as carbohydrates, proteins and fats into simpler
substances such as glucose, amino acids and fatty acids respectively is called digestion.
Digestion in human beings is carried out in the alimentary canal of the digestive system. 

1. Food is crushed and  broken into small particles in the mouth  with the help of  teeth. 
2. It is then mixed with saliva.  
3. This  chewed  soft  food  then  passes  through  the  oesophagus  in  a  wave-like  movement  (peristalsis) and moves to the stomach. 
4. In the stomach, food mixes with gastric juices and HCl.  From the stomach, the food moves into the small intestine. 
5. In  the  small  intestine,  carbohydrates,  proteins  and  fats  are  broken  down  with  the  help  of  juices secreted by the pancreas, the liver and the small intestine itself. 
6. The broken down food is then absorbed by small projections present on the inner walls of the intestine called villi.   
7. Finally, the food moves into the large intestine where most of the water is removed from the food and is then thrown out of the body through the anus.