Define Immunity, Active and Passive immunity

Define Immunity, Active and Passive immunity

• The resistance of the body towards the pathogen and its toxin is known as immunity.

• Immune immunity are of two types - The immunity that is present naturally during the course  of life time is called natural acquired immunity. This kind of immunity may be active or passive.

Active immunity

• Natural active immunity is the resistance that is developed due to the fact of memory cell on exposure of first time of any infection.

Read about the Our Immune System

• On exposure of same antigen on second time, massive antibody are produced by the body. This type of immunity is most effective and remain present for long time in body

Passive Immunity

• The immunity that is present in infants and acquired from the mother through the placenta or colostrum is called natural passive immunity.

• This type of immunity is only temporary protection against infection. This immunity is very slow.

• Passive immunity also developed by the colostrum. It also has several antibodies that provide protection against the infection.

Immunity developed by Vaccine 

• The immunity is developed by the injection of a small amount of antigens called vaccines. 

• This vaccine stimulates the manufacture of antibodies against the antigens. This type of immunity is called as artificially acquired immunity.

• Generally a booster dose is given that produces antibodies that are long lasting and prevent infection for a long time.

• Several types of vaccine currently are used. Toxoid vaccination are used for tetanus and diphtheria, Killed organisms like dead viruses and bacteria are used in immunization purpose.

• Modified living organism are injected into body where they multiply without producing any disease.

• Such modified organism are used to treat tuberculosis, Polio, Rubella etc. The immunity that is developed by the through injection of serum present in already immunized organism.

• The antibodies firstly are extracted from an individual and injected in to the blood of another person. But this immunity is short lived. This is called artificial passive immunity.

Innate immunity -

• This type of immunity is non specific and work on the principal of barriers.

• Skin and Mucus coating of Respirarort tract, Digrstive tract , urogenital tract etc are physical barriers. These barriers prevent the entry of pathogen into the body.

• Hydrochloric acid, Saliva, tears in eye etc act as a physiological barriers to inhibit the entry of pathogen .

Read more about the Protein need against the infection

• Poly morpho nuclear leukocyte PMNL Like Neutrophils, monocytes, lymphocyte macrophages are cellular barriers.

• Virus infected cell release a chemical called interferon which protect non infected cell of body. This one is cytokine barriers.