what is Immunity


what is Immunity? types of Immunity | what is Initiate immunity? what is Acquired immunity? differences between Acquired immunity and Initiate immunity?


what is Immunity? types of Immunity | what is Initiate immunity? what is Acquired immunity? differences between Acquired immunity and Initiate immunity?

The resistance offered by the host to the harmful effects of pathogenic microbial infection is called immunity. Immunity is of different types:-

Initiate immunity.

Acquired immunity.

Initiate immunity:-

Innate immunity is the basic immunity which may be genetically passed on from one generation to another generation.

It does not depend on prior contacts with microorganisms {or} antigens.

It may be non specific which indicates a degree of resistance to all infections.

Species immunity:-

Individual of some species uniform pattern of suspect ability two different bacterial infection.

The mechanism of species immunity psychological and biological differences between tissue to post which determines whether {or} not pathogen can multiply in them

For example:- poliomyelitis, measles, symphalis leprosy occurs in man.

Racial immunity:-

Within a species different phrases how differences in susceptibility to infection.

For example:- negros resistant to malaria and suspect able to yellow fever where as indians are resistance to yellow fever but suspect able to malaria fever.

Such racial differences are known to be genetic in origin principally induced by environmental factors.

Individual immunity:-

Individual in population shows variation in their response to microbial infection.

Homozygous twins exhibit similar degree of resistance {or} respectability against to pathogen.


Mechanism of innate immunity:-

The differences mechanism of the body are related to body coverings.

There are as follows:

Epithelial surfaces:-

The intact skin and mucous membrane the body confers unit. The provides “bactericidal secretions”.

Myaledity of stomach inhibit bacterial multiplications.

The normal body flora play director role indifferent of body.

For example:- intestinal flora by producing bacteriocines which are destructive to other bacteria.

Tissue differences:-

If barrier body is overcome by the organisms number of factors in the normal tissue and body fluid play this rule.

Tissue factors may be divided into two types. They are

Humoral factors

Cellular factors

Humoral factors:-


it is bacterial enzymes found in nasal intestinal secretions and seminal fluids lysozyme degrades peptidoglycon present in the bacterial cell wall.

Piperidine: it is a protein present in normal serum. Which lysis of gram negative bacteria with the help of mg2+ and complement.

Basic polypeptide: these are bactericidal cancel active at high ph {or} alkaline ph. The acts upon cellular causing cell disintegration. For example: lukins from leukocytes.

Complement: it is thermostable substances present in serum and tissue fluid it enhances phagocytes and kills bacteria synthesized by specific antibody.

 Cellular factors:-

Phagocytosis:- phagocytosis is the process by which phagocytic cell in just and destroy the bacteria. Macrophages and monocytes act as phagocytic cell.

Phagocytic cells reach sites of inflammation in large number and just the antigen. Bacteria are phagocytes into vacuole it is my as phagosome.

The phagosome lysis with lysosome to form phagolysosome. Bacteria are subjected to the action of lytic enzyme in phagolysosome and all destroy.


Tissue injury {or} irritation initiates by entry of bacteria leads to inflammation. It is important non specific mechanism of defence initially constitute and then dilution of blood vessels at affected sites is followed by migration of phagocytic cell to that particular area microorganisms are phagocytose and destroy the phagocytic cells out of plasma helps to dilute the toxin products.


It is nature defence mechanism, it may be actually destroy the infecting organisms. Fever stimulates the production of interferons and help recovery from viral infection.


Acquired immunity:-

The immunity acquired during the lifetime of an individual is known as acquired immunity.

It is not inherent in the body but it is acquired during life.

It requires a prior contact with an antigen.

This is the type of immunity specific for a single type of microorganisms.

Acquired immunity may be two types. They are:-

Active immunity.

Passive immunity.

Active immunity:-

Immunity is resistance developed by an immunity as a result of antigenic stimulus. In this type of immunity the body is actively involved in the production of antibody. Active immunity may be divided into two types:-

Natural active immunity.

Artificial active immunity.

Natural active immunity:-

The goal of immunization is protective immunity and immunological. A subsequent exposure to the same antigen successful elimination of pathogens.

Example:- a person attacked by mealse {or} smallpox develops natural active immunity during his lifetime.

Immunity attained after bacterial infection is less permanent the after viral infection.

Immunity of same viral infections like influenza is short lived due to antigenic variation.

Artificial active immunity:-

Immunity attend by host in response to vaccination is called artificial active immunity.

Administration of vaccines is called vaccination.

Vaccines most commonly used are toxoids, combined vaccines.

Passive immunity:-

Immunity that is required by non immune individual by transfer of antibodies are called passive immunity. It is of two types:-

Natural passive immunity.

Artificial passive immunity.

Natural passive immunity:-

Immunity transferred from mother to child. In mammals antibodies cross the placenta during pregnancy and transfer also occurs orally through colostrum.

Artificial passive immunity:-

Transfer of immunity for man immunised donor to non-immune individual used in the treatment of tetanus, diphtheria, hepatitis, measles, snake bite, black window, spider bite.

It can brought about by hyper immune serum of human {or} animal origin.

f Example:- antiserum, pooled sera combined immunization etc,.


Adaptive immunity:-

Immunity produced by injecting immuno genetically component lymphocytes.

Adapted in the treatment of tuberclosis and leprosy.

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