Immunology: Immune System

And Its Type


  • About
  • Immune system
  • Immunity
  • Types of immunity
  • Innate immunity
  • Acquired immunity


  • Immunology refers to the branch of biology that deals with the study of immune system in all organisms.
  • Any malfunction in this system lead to the diseases like autoimmune disease, hypersensitivity, transplant rejection and immune deficiency.
  • The term was given by Ilya Ilyich Mechnikov and received noble in 1908 for his work. He studied on the larvae of starfish, pinned thorns into the larvae and found unusual cells surrounds the thorns. This was the active response by the larvae. Mechnikov was the first to observe phagocytosis.

Immune system:

  • A different type of cells and molecules which protects our body from pathogens is collectively called immune system.
  • Pathogens may be anything from algae, fungi, bacteria to haptens (molecules that may cause an immune response).
  • The cells and molecules of the immune system were distributed all over the tissue of the body which plays role in elimination or prevention from pathogens.


  • Immunity is the ability of organism to protect itself from the disease causing organism.
  • Our body regularly comes in the contact of numerous pathogens but we few results into disease the reason is that our body develops antibody against the pathogen and protect from the disease.


  • Innate immunity
  • Acquired immunity

Innate immunity:

  • Innate immunity is the type of immunity with which the individual is born.
  • It serve as the first line of defence an provided various components like skin, mucus membrane phagocytic cells.
  • The mechanisms of innate immunity are anatomical barrier, physicochemical barrier, phagocytic barrier and inflammation.

Types :

Species immunity: one species are resistance but other are susceptible to the same infection. Example, birds are resistant to the anthrax but human doesn’t.

Racial immunity: one race is susceptible other is more resistant to same infection. Example, certain African race are resistant to malaria but Asian or Americans are susceptible.

Individual immunity: to a certain infection the individual of race or cast is resistant but other individual of same race is susceptible to the same infection.

Acquired immunity:

  • The immunity which the individual get during its life span after each microbial infection is called acquired immunity. Example is an individual was ever infected by any infection like chicken pox virus he/ she become life time resistant to chicken pox.
  • Antibodies and t-lymphocytes contribute in acquired immunity.
  • The t-cells and antibodies are specific to the pathogen hence acquired immunity is also known as specific immunity.


Active immunity

  • The active immunity is the condition when the host itself produces antibodies.

There are two types of active immunity

Artificial – by vaccination

Natural – by natural infection

Passive immunity

The condition in which the host doesn’t produces antibodies itself but antibodies developed in other host cell provides immunity known as passive immunity.

Two types:

Artificial – antibody introduced in the host body for immunity

Natural – antibody from the mother to foetus.


Antibodies are the immunoglobulin found in the blood and serve as protection against substance like antigen.

Antigens are the protein or carbohydrate which activates the immune system.

There are 5 types of antibodies- IgA, IgM, IgG, IgE and IgD.

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