WHAT IS IMMUNITY &TYPES

Immunity:- It refers to the ability of immune system to fight against pathogens. It is

of two types:

1)innate immunity

2) aquired immunity

1)Innate immunity:-T

he immunity that is present at the time of birth of an individual

is known as innate immunity.Also called non-specific immunity, it is inherited or

passed genetically from parents to children.It also provides the first line of defense

to the body.

(i) A physical barrier such as skin.

(ii) Physiological barriers such as pH of the stomach, bile juice.

(iii) Cellular barriers such as leucocytes, macrophage cell.

(iv)a cytokine barrier 

(i) physical barriers:-they play an important role in preventing microbes from reaching tissues that are susceptible to infection. At the cellular level, barriers

consist of cells that are tightly joined to prevent invaders from crossing through to

deeper tissue for example skin is the most important physical baarier present in our

body ,the mucous membranes lining the nose, mouth, lungs, and urinary and

digestive tract protect us.

(ii) physiological barriers:- these are the state of person's mind that can limit their

ability to make the right decisions. Psychological barriers also affect the human

capacity to communicate with others with a logical state of mind. Psychological

barriers are also known as emotional barriers.

(iii) cellular barriers:-WBC(leucocyte) and NK cells(natural killer) in the blood are

two types of cells that act as cellular barriers to provide the innate immunity in

humans.cells.These are phagocytic in nature 

(iv) cytokine barriers:-the cytokine inhibits the viral replication.they can form an

innate immune system by formation of physical baariers virus-infected cells secrete

proteins called interferons

Which protect non-infected cells from a further viral infection is a cytokine barrier.

2) Acquired immunity:- also known as adaptive immunity.The resistance that an

individual acquires during a lifetime due to exposure to the microbes are called

acquired immunity. These are highly pathogens specific and can differentiate

between the self and non-self .These type of immunity recognizes and kills

pathogens.

The two types of acquired immunity are :

i) active immunity

ii) passive immunity

(i) active immunity:-the antibodies which are itself produced by body are calledactive immunity.they are slow process.active immunities are of two types:

(i)natural:-antibodies which are formed against natural infections

(ii) artificial:-antibodies which are formed against artificial infections and given in the

form of vaccination in weak form example:- vaccination for o.p.v(oral polio

virus),b.c.g(bacille Calmette-Guerin)

(ii) passive immunity:- preformed and readymade antibodies are use which are

fast.

they are of two types:

(i) natural:- these are provided when a person is given antibodies to a disease rather

than producing them through his or her own immune system. A newborn baby

acquires passive immunity from its mother through the placenta.

(ii) artificial:- the immediate, but short-term immunization provided by the injection of

antibodies, such as gamma globulin, that are not produced by the recipient cells.