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.
- Food is crushed and broken into small particles in the mouth with the help of teeth.
- It is then mixed with saliva.
- This chewed soft food then passes through the oesophagus in a wave-like movement (peristalsis) and moves to the stomach.
- In the stomach, food mixes with gastric juices and HCl. From the stomach, the food moves into the small intestine.
- 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.
- The broken down food is then absorbed by small projections present on the inner walls of the intestine called villi.
- 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.