Immunology

Animals and human beings are continually exposed to various infectious agents like bacteria, viruses, fungi and parasites. It has long been noticed that survivors of certain diseases ex. Measles, are not attacked by the same disease again. Clearly, these people have become immune to the concerned disease. The system of animal body which protects it from various infectious agents and cancer is called Immune system. A study of the immune system is known as Immunology.

The latin term "Immunis" meaning "exempt" or "freedom" gave rise to the English word Immunity. It refers to all the mechanisms used by the body for protection from environmental agents that are foreign to the body. These agents may be micro organisms or their products, certain food items, chemicals, drugs and pollen grains.

Immunity is of two types:

• Innate immunity:(Non specific immunity)

Innate immunity comprises all those natural defense mechanisms with which an organism is protected from infection. Innate immunity consists of various types of barriers that prevent entry of foreign agents into the body. The pathogens that enter into the body are quickly killed by some components of the immune system. This is the first line of defence in most animals.

• Acquired immunity (Specific immunity)

This is capable of recognizing and selectively eliminating specific microorganisms. Acquired immunity is found only in vertebrates. It supplements the protection provided by innate immunity. It is generated in response to an exposure to the micro organisms. Specific defence mechanisms require several days to be activated .