Immunology refers to the study of how the body protects itself against infectious diseases caused by bacteria, viruses, protozoa, and fungi, and also parasitic organisms like helminth worms. . It deals with all the defense mechanisms including all physical, chemical and biological properties of the organism that help it to combat to foreign organisms, material, etc.

The word immunity was derived from the Lain word “immunis” meaning exempt.

The immune system consists of two parts: innate immune system and adaptive immune system

The innate immune system utilizes certain strategies to provide a rapid, response when alerted by certain typical signals of infection.

The adaptive immune system that is able to form specific responses to target infection with extraordinary accuracy.

Immune system key lymphoid organs:

The primary lymphoid organs of the immune system are bone marrow and thymus and the secondary lymphatic tissues like tonsils, spleen, adenoids, lymph vessels, skin and lymph nodes.

Secondary lymphatic tissues can be surgically removed easily without much harm to humans.

The actual components of the immune system are cellular in nature and not associated with any specific organ.


Vaccines can be used to protect our body and prime the immune system; this helps the immune system to defense against the harmful organisms which makes our body weak and unhealthy. Vaccinations are given to protect against these diseases smallpox, polio, tuberculosis, measles, mumps, and rubella amongst others.

There are several effective vaccine as well they are HIV, Hepatitis C and Malaria to protect against such deadly diseases.