human digestive sytem (part – 1)

Chemical substances which are present in our food are called Nutrients. Nutrients may be organic or inorganic in nature. The organic constituents are carbohydrates, lipids, protein & vitamins. The inorganic constituents of nutrients are minerals and water. Depending upon the quantity or functions, nutrients may be of two types:

  • Macronutrients: these nutrients provide energy. Such as carbohydrates, protein & lipid.
  • Micronutrients: although they do not provide energy yet their deficiencies cause specific diseases and abnormalities. It include minerals, vitamins and water.


Food is one of the basic requirements of all living organisms. The major components of our food are carbohydrates, proteins and fats. Vitamins and minerals are also required in small quantities. Food provides energy and organic materials for growth and repair of tissues. The water we take in, plays an important role in metabolic processes and also prevents dehydration of the body. Bio-macromolecules in food cannot be utilized by our body in their original form. They have to be broken down and converted into simple substances in the digestive system. This process of conversion of complex food substances to simple absorbable forms is called Digestion and is carried out by our digestive system by mechanical and biochemical methods.

The human digestive system consists of the Alimentary canal and the associated glands